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YAWL - User Manual

1. u http flocalhost 8080 resourceService Faces userWorkQueues jsp E gt eg Google Offered 0 Allocated 0 Started 1 Suspended 0 27 1 ReceiveSSN_3 CreditRatingProcess ywi ReceiveSsn View Edit Reallocate sil Reallocate sif New Instance BAD PROCESS DEFINITION Data extraction failed schema validation at task completion Task ReceiveSSN_3 XQuery ssn ReceiveSSNissn s ssn Document lt ReceiveSSN lt ssn qutl 23 lt ssn lt ReceiveSSN Schema for Expected xs schema xmIns xs httpvAwww w3_org 2001MLSchema i gt But received lt ssn lt ssn qutl 23 lt ssn lt issn gt Validation error message Error 4 9 cvc type 3 1 2 Element ssn is a simple type so it must have no element information item children Figure 5 12 An error indicating invalid semantics of an XQuery used in the specification YAWL Specification Figure 5 13 shows the YAWL net specifying the above simple make trip process There are five labelled tasks register for registering for the trip pay for making payment and the other three tasks for making the corresponding bookings The task register has an OR split decorator and the task pay has an OR join decorator gt Make Trip Process book flight register book hatel book car Figure 5 13 The simple Make Trip Process net Figure 5 14 shows the data type definitions in this process There are two new data types
2. 23 24 CHAPTER 3 GETTING STARTED WITH YAWL management system if you prefer Its tongue in cheek name belies the fact that YAWL is rather unique It s based on a very rich workflow definition language capable of capturing all sorts of flow dependencies between tasks It has open interfaces based on Web standards which enable developers to plug in existing applications and to extend and customise the system in many ways It also provides a graphical editor with built in verification functionality which helps solution architects and developers to capture workflow models and to automatically detect subtle but potentially nasty errors early on in the piece Finally YAWL is arguably the most mature open source workflow management system around From its beginnings as an academic prototype YAWL has evolved into an enterprise grade workflow engine thanks to contributions from the YAWL Foundation members and from the organisations and individuals who have used it This demonstrated commitment from its users and community of developers also ensures the continuity of the system If you think YAWL might be for you you may be wondering how to learn more This chapter provides a gentle introduction to the YAWL workflow system The aim of the chapter is to help people to get YAWL up and running with a minimum of fuss The chapter doesn t cover all possible features and components of YAWL Instead it focuses on some essential aspects that w
3. A add XQuery of entire element lt StudentNumber gt populates the task variable StudentNumber KH Create Done Cancel Figure 4 31 Passing a net s StudentNumber value to a Task variable To add an Output Parameter 1 First select the task to add the parameter to We will be setting up Output Parameters for the variables that we created in the Adding Updating Task Variables section Go to the Attend University Net and select the Enrol task 2 Right click on the task and choose Update Parameters An Update Parameters dialog box will appear Figure 4 31 ra Update the Parameters for the Enrol task 3 In the Output Parameters section click on Create An Update Net Parameter dialog box will appear similar to Figure 4 31 4 If you have already set up a Task Variable for this task then the Existing Task Variable option will be activated and there will be a list of task variables to choose from Choose a variable from the list and click on Done then Done again to close the task parameters dialog If you haven t set up Net 4 5 ADDITIONAL SPECIFICATION FEATURES 71 Variables then click on Create and return to the previous section Section 4 5 3 If you are familiar with XQuery syntax then you can paste in an XQuery to allow manipulation of the Output Parameters Syntactically well formed XQueries will be green and badly formed ones will be red For workflow design
4. 1 Click on the Add a Condition button oO in the Elements panel or right click on an empty part of the canvas and choose Condition Go to the Study Privately Net We are going to place a loop Condition after the Read a Book atomic task to determine whether we gained any knowledge from the book We will add the new Condition next 2 Place your Condition in your Net and set the name by right clicking on the Condition and choosing Set Label Call this Condition Knowledge Gained 3 Now link to the Condition to the tasks of the net using flow relations Select the flow relation between the Read a Book atomic task and the Feel Smarter Atomic Task and delete it Create a flow relation from the Read A Book task to the Knowledge Gained condition 4 Create a flow relation from your condition to a task Set the flow relation from the Knowledge Gained condition to Feel Smarter atomic task 5 Create another flow relation from your condition to another task to signify the two possible flows from the condition Before we create our second flow relation from our condition first create another atomic task and call it Look for An Easier Book Add an XOR join decoration to the Read a Book task with the orientation being West Finally create the Flow Relation from the Knowledge Gained condition back to the XOR join of the Read A Book atomic task as per Figure 4 13 6 Vali
5. 4 5 2 Data Type Definitions YAWL uses XML Schema to define data documents that are passed from net to task and back during the life of a workflow instance There are over 40 simple XML Schema data types string integer boolean etc all of which are supported by YAWL User defined data types are also supported by allowing for the definition of XML Schema complex types which are added to a specification and then may be used to define variables based on those types To define a new complex type for a specification 1 Select Update Data Type Definitions from the Specification Menu 2 Enter your XML Schema Data Type Definition into the dialog box See Figure 4 21 3 If the definition text is green your new data type is a valid definition and may be used for defining Net or Task variables in your specification If the text is red there is something wrong with your data type definition and the data type will not be available When the text is red the split pane will reveal a table listing parse errors that were collected when determining the validity of the text supplied An example of this is shown in Figure 4 22 Open the Data Type Definitions dialog and type in the XML text that appears in Figure 4 21 The above example creates a complex data type called Geek that has two separate sub components Name and Salary of type string and double respectively Types called Book and Booklist are c
6. Figure 5 19 Parameter definition for task pay process by involving a multiple instance composite task for execution of the simple make trip process for each leg Also the customer is provided with a subtotal of the payment for each leg and the subtotals for all the 112 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL legs in the trip will be calculated into a total payment at the end of the process YAWL Specification Figure 5 20 shows the YAWL net specifying the above make trip process There are two nets the root net called make trip and the subnet specifying details for the composite task do itinerary segment which is basically the simple make trip net in the previous example F make trip register do itinerary segment Ol do itinerary segment book flight register itinerary book car Figure 5 20 The make trip net with a multiple instance composite task do itinerary segment and the corresponding subnet Figure 5 21 lists the data type definitions in the make trip net There are five new user defined data types The itineraryType contains a list of itinerary segments of itinerarySeg Type which each comprises information of departure location destination startDate endDate flightDetails hotelDetail carDetails and subtotal The legsType is a set of legs of legType which provides the information of departure location and destination Finally the serviceType specifies
7. lt element name Custinfo gt lt complexType gt lt sequence gt lt element name CustName type string gt lt element name T argetStarntD ate type date gt lt sequence gt CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL Figure 5 1 A YAWL net PerformBooking and its data representation lt Decide gt F WantFlight WantHotel Decide lt complexType gt lt element gt lt sequence gt lt complexType gt lt element gt lt schema gt Figure 5 2 XML Schema of a user defined data type for CustInfo Editor 5 3 Data Transfer 5 3 1 Internal and External Data Transfers Note In Chapter 4 Section 4 5 3 to Section 4 5 6 illustrate how to define net and task variables in the YAWL YAWL supports data passing between variables which can be considered internal data transfer and data interaction between a process and its operating environment i e workflow engine users and web services 5 3 DATA TRANSFER 101 which can be considered external data transfer Internal data transfer is always conducted between nets and their tasks which themselves may or may not be composite using XQueries Note that YAWL does not support direct data passing between tasks This is because each task variable is local to the task that the variable belongs to i e it is not accessible by other tasks Assume task A and task B in net N To pass data from task A e g variable Va to t
8. 3 Combine the private key the Document fingerprint and the X 509 certificate to create the digital signature using PKCS 7 encryption 4 The fingerprint and the private key are used to calculate the signature itself and the X 509 certificate gives the publisher details Figure 8 3 An overview of the production of a digital signature A digest SHA1 of the document is included in the signature Since the Document has a unique fingerprint the digital signature only applies to this document The p12 certificate is protected by a password and is only used to sign the document The public certificate X 509 contains the information about the signer and the public key that can be used to check the validity of the signature It is public because anybody should be able to access the content of the signature to verify it But without the private key it cant be reproduced 8 4 2 Verification of the Digital Signature 1 Calculate the document fingerprint with the same algorithm than the signer used 2 To verify the Digital Signature you need first to extract the certificate X 509 The certificate X 509 contains all the information needed to identify a user It is not encrypted and can be seen freely We use the public key contained in this certificate to decrypt the signature using the same algorithm 3 If the signature matches the digest message of the document then the signature is considered valid Anybody can verify the signature
9. Fa Update Parameters for Atomic Task ReceiveSSN B Update Het Parameter ssn input Parameters from element of task variable ss ee O Oa Task Variable Create war Ssn atid XOuery of Glement s content D from expression fh add XQuery of entire element Upekate Query iggi FeceiveSS5N 22n texti Remove Net Variables Task Variables Name Type Usage Namel Type Usage aan string Local a ssm string Output Only IT rating double Local i fault string Local Output Parameters Query NetVariable zari Receiveg3H san text a F lt issne populates the net variable ssn Figure 5 7 Parameter definition for task Receive SSN starts with zero Otherwise the flow leading to task DecideRating will be taken Since the flow evaluation is performed from the top most flow to bottom most flow at run time the bottom most flow will be used as the default The query CreditRatingProcess ssn text can be generated by clicking the XPath Expression button in the Update Flow Predicate dialog Figure 5 9 shows the parameter definition for task ReportFault The variable fault is used to carry the fault information Bankruptcy It is defined as input only because the fault information is only used for client notification upon execution of the task Figure 5 10 shows the parameter definition for task Decide
10. If the optional YAWL specification analysis utility wofyawl exe is supplied in the same directory as the Editor an extra tab entitled WofYAWL Analysis will be enabled in this dialog allowing more analysis options than those supplied by default The utility must be compiled for specific architectures The current version of the Editor needs version 0 4 of the utility 3WofYAWL is currently only available for Windows environments 84 CHAPTER 4 THE EDITOR Configure Specification Analysis WofYAWL Analysis Wi Use the reset net analysis algorithm Use YAWL reduction rules before analysis for optimisation Use Reset reduction rules before analysis for optimisation __ Check for weak soundness property using coverability Check for unnecessary cancellation regions Check for unnecessary or joins MI Check for or joins ina cycle M Check for soundness property using reachability results from bounded nets C Show observations in analysis results These tests may overlap in identifying unreachable tasks in the specification potential deadlocks and possible unfinished work in completed workflow cases rd Keep Analysis progess dialog open when Analysis completes Done Cancel Figure 4 44 Configure Specification Analysis dialog Analysing Specification Completed Immediate Successors 29 Immediate Successors 24 Immediate Successors 19 Immediate Successors 14 Imme
11. Users adamsmj Documents research temp myCareer yawl B lel ele y alm Sle la alti assa ww s sls Dolo Q r We My Career _ Study_Privately _ Attend_University Od LJ Task Icon Begin My Attend Get a Job Career No Icon Career University Started b fa Manual b Automated b 4 Routing E ae Bad Task Study Privately F h Atomic Task Bad Task 228 is not on ESAERA directed path between the input and output conditions Left click on the selected net to create a new atomic task Figure 4 42 A invalid specification Specification File Save Options Specification ID InsuranceClaim Version Number 0 1 Kil Verify on save Vv Analyse on save Mi Auto Increment Minor Version Number wi Create backup oK Cancel Figure 4 43 Specification File Save Options dialog numbers consist of a major part to the left of the point representing a major revision and a minor part to the right of the point representing a minor revision Version numbers begin at 0 1 you may edit the version number directly to a higher version number at any time If the Auto Increment Minor Version Number checkbox is checked the minor revision will increase by one each time the specification is saved The Verify on save and Analyse on save checkboxes if checked will verify and and or analyse the specification before it is saved providing a final check of
12. and Signature Note that usage type of the Signature is Input amp Output You may also have to change the paths in the upload jsp file where the default values are localhost they 202 CHAPTER 8 OTHER SERVICES 1 The Yawl Worklist redirects the user to the custom form of the Digital signature 2 The User uses a Custom form to give the Public certificate the key store and Service the password to open the key store Public Certificate aN Password Document PA 7 Signed fingerprint N Digital Signature P1 Certificate 4 The custom form ends the task and redirects the user back to the Password Worklist Items x509 Certificate Pareourit_ subm Clear J Key Store Public Certificate Password Document Signed Digital Signature Service 3 The Web Service computes the Digital fingerprint and returns it to the Custom may have to be changed to the actual address where the service runs if it is not running locally String Path http localhost 8080 DigitalSignature files String redirectURL http localhost 8080 resourceService faces userWorkQueues jsp workitem _ wir toXML The last task is the custom service part it has to be specified in the YAWL Registered Service Details panel of the Task Decomposition dialog Figure 8 13 The Signature will be checked with the certificate loaded in the jsp page and it will
13. TI Suspend Case suspends all live workitems in the current case instance a live workitem has a status of fired enabled or executing effectively suspending execution of the case AW Suspend All Cases suspends all live workitems in all of the currently executing instances of the specification in which the workitem is defined effectively suspending all running cases of the specification D Continue Workitem un suspends or continues execution of the previously suspended workitem gt Continue Case un suspends execution of all previously suspended workitems for the case effectively continuing case execution D Continue All Cases un suspends execution of all previously suspended workitems for all cases of the specification in which the workitem is defined or of which the case is an instance effectively continuing all running cases of the specification m Remove Workitem removes or cancels the workitem execution ends and the workitem is marked with a status of cancelled No further execution occurs on the process path that contains the workitem 7 4 USING THE WORKLET EXCEPTION SERVICE 155 m Remove Case removes cancels the case Case execution ends m Remove All Cases removes cancels all case instances for the specification in which the workitem is defined or of which the case is an instance KI Restart Workitem rewinds workitem execution back to start Resets the workitems data values
14. YAWL User Manual 2009 The YAWL Foundation Contents 1 Introduction EE PV Et NN LG ey ae czy Se oa eve wh ea eee Se ee ee Se wae ee ae Se e a E O E 1 2 Obtaining the Latest Version of YAWL 4 c04 4 keke Oo eR ee wR ER ee 2 Leo he YAW le POungationm 4 6 6 ahem bb eae ee ee ee eee we A eee x LA DOUM CNO yk wurde oe Ree EY ee Ye eee gp ook eon oe i ee ed ee 2 Installation 2k Regue lt 6 4 4 b Go se ES oe a ee RS eee net be Se Bee ee eo De JAWE SUG ea AG ee oe amp eee ea OGG eee Oe ERR OER Dor YOAV lo GCE OrISCs 3 te Mt ak aa tse Gs oh eta ee eet oe we Sa ok ok A ho Byres DA NEA ve Soe tod dota hod ee oe GE Ra hoe ES RSS bbe bs Shoe eee aS Za Whe AMSG AWACIOMs 4 0 be Stee e e a hg eo ee er ee te Se a a we GE eee ee 3 Getting Started with YAWL ook APOC UCUlOMs in eh ke Ee eRe ee Se oe ee ee BB ER ERE ES Bees 8 2 Temno otr e ey Je ute ade ke ote Th BE ae Ss Ee ee a he ie a a ele ete A E 3 3 Building a Simple Workflow Example a aoa ao a a a aa 3 4 Advanced Workflow Concepts 1 oaoa a a a a a aa 39 Where To Fron Heres es 4 sheer eSNG G44 BOSSES DGS a a A a 4 The Editor 4 1 Launching the YAWL Editor aaa aa SS ee Oe ad EE Se we BE ote Bae El AD The AW Ih Editor Workspace sx lt lt 1 cca eee ee oo ah ee Bb ce amp A EA oh eee 4 3 Creating Your First Specification 4 a 4 82 4 06 see ye aed Re Se EER KRA SERRE YEY 4 4 Changing the Appearance of Your Specification oaoa
15. Click on the Add Multiple Instance Atomic Task button Gl in the Elements panel or right click in an empty part of the canvas and choose Multiple Atomic Task ra Go back to the My Career Net We are going to replace our existing Do Private Study Atomic Task with a Multiple Instance Atomic task so click on the Do Private Study Atomic Task and delete it We will add in the new Multiple Instance Atomic task next 2 Place your Multiple Instance Atomic Task in your Net and set the name of this task by right clicking on the task and choosing Select Task Decomposition ra Give this task the same decomposition as before by selecting Do Private Study from the drop down list Reconnect the flow relations from Begin My Career to Do Private Study and from Do Private Study to Get A Job as per Figure 4 11 C Attend University Attend University Begin My Career Started Do Private Study Figure 4 11 Adding a Multiple Atomic Task 3 You will now need to set the parameters of the MI Task which being multiple instance needs a few more values set than a simple atomic task Right click on the task and choose Set Instance Detail Ensure that you are viewing the Bounds tab of the dialog as per Figure 4 12 4 Choose the Instance Creation mode In either mode the number of task instances created at runtime for the task will be between the values given for Minimum I
16. For a new participant entries for first name last name userid and password new and confirm are required Userids must begin with a character and may contain the letters digits and underscores Passwords must be at least 4 characters in length The description note and administrator fields are optional as are privilege settings by default all are unselected and role position capability memberships When you have finished adding participant information click the Add button You may cancel the addition at any time by clicking the Reset button instead of the Add button 130 CHAPTER 6 THE RUNTIME ENVIRONMENT Oe Aw LO gg ad ee Oe Participant Corleone Don Vito Privileges First Name Don Vito Vito Choose Which Work Item to Start LastName Corleone C Start Work Items Concurrently User ID dve M Administrator C Reorder Work Items Description View All Work Items of Team C View All Work items of Org Group C Chain Work Item Execution Manage Cases Order a Manage PO Manag t Senior Credit Officer Remove Figure 6 9 User Management e To Modify a participant select them from the list then add or change the desired fields then click the Save button e To Delete an participant select them from the list and click the Remove button User Privileges Primarily each participant may be designated a user the default or an administrator To grant admin istrator p
17. Lecture Notes in Computer Science pages 216 232 Porto Portugal 2005 Springer N Russell A H M ter Hofstede D Edmond and W M P van der Aalst Workflow data patterns Identification representation and tool support In L Delcambre C Kop H C Mayr J Mylopoulos and O Pastor editors Proceedings of the 24th International Conference on Conceptual Modeling ER 2005 volume 3716 of Lecture Notes in Computer Science pages 353 368 Klagenfurt Austria 2005 Springer N Russell A H M ter Hofstede D Edmond and W M P van der Aalst newYAWL achieving com prehensive patterns support in workflow for the control flow data and resource perspectives Technical Report BPM 07 05 BPM Center 2007 http www BPMcenter org N C Russell Foundations of Process Aware Information Systems PhD Thesis Queensland University of Technology Brisbane Australia 2007 Available through http www yawl system com H M W Verbeek Wil M P van der Aalst and Arthur H M ter Hofstede Verifying Workflows with Can cellation Regions and OR joins An Approach Based on Relaxed Soundness and Invariants Computer Journal 50 3 294 314 2007 M Weske Business Process Management Concepts Languages Architectures Springer 2007 Moe Thandar Wynn Semantics Verification and Implementation of Workflows with Cancellation Regions and OR joins PhD Thesis Queensland University of Technology Brisbane Australia 2006 Available through http www
18. Note that it is not necessary to map all available case data to a worklet enabled task only that data required by the Service to make an appropriate decision How this data is used will be discussed later in this manual The list of task variables in Figure 7 7 also show that most variables are defined as Input Only this is because those values will not be changed by any of the worklets that may be executed for this task they will only be used in the selection process The last three variables are defined as Input amp Output so that the worklet can return or map back to these variables data values that are captured during the worklets execution The dialog has a section at the bottom called YAWL Registered Service Detail It is here that the task is associated with the Worklet Service by choosing the Worklet Service from the list of available services Note that list of services will only be seen if the Engine is currently running and it has services installed Select the Worklet Service from the list That s all that is required to make the top level specification worklet enabled Next we need to create one or more worklet specifications to execute as substitutes for the worklet enabled task 150 Standard Extended Attributes 3 CHAPTER 7 THE WORKLET SERVICE Task Decomposition Label Treat Task Decomposition Variables Mame Type Usage SeX string Input DiastolicBF long Input Notes string Input
19. Petia Wohed Michael Adams Moe Wynn and Marcello La Rosa This forms the basis for Chapter 2 Its introduction forms the basis for Chapter 1 Chapter 1 Introduction This chapter provides a brief background introduction to YAWL and the YAWL Foundation 1 1 What is YAWL Based on a rigourous analysis of existing workflow management systems and workflow languages a new workflow language called YAWL Yet Another Workflow Language was developed by Wil van der Aalst Eindhoven University of Technology the Netherlands and Arthur ter Hofstede Queensland University of Technology Australia in 2002 This language was based on the one hand on Petri nets a well established concurrency theory with a graphical representation and on the other hand on the well known Workflow Patterns www workflowpatterns com The Workflow Patterns form a generally accepted benchmark for the suitability of a process specification language Petri nets can capture quite a few of the identified control flow patterns but they lack support for the multiple instance patterns the cancellation patterns and the generalised OR join YAWL therefore extends Petri nets with dedicated constructs to deal with these patterns YAWL offers the following distinctive features e YAWL offers comprehensive support for the control flow patterns It is the most powerful process specification language for capturing control flow dependencies e The data perspective in YAWL i
20. Platforms section with default settings for a number of different database platforms all except one PostgreSQL commented out see Listing 2 1 for an excerpt of the properties file To configure for a different database platform comment out the currently enabled platform then uncomment the platform of choice ensuring the username and password values match the target database authorisations Remember to change the hibernate properties file for each of the webapps mentioned above 7Please pass on your experiences using YAWL with database platforms other than those listed on the YAWL SourceForge forum 22 HypersonicsQL hibernate hibernate hibernate hibernate connection connection connection connection PostgresQL CHAPTER 2 INSTALLATION dialect org hibernate dialect HSQLDialect hibernate driver_class org hsqldb jdbcDriver username sa password url jdbc hsgqldb file webapps yawl yawl hibernate dialect org hibernate dialect PostgreSQLDialect hibernate connection driver_class org postgresql Driver connection url jdbc postgresql yawl connection username postgres hibernate hibernate hibernate connection password yawl hibernate query substitutions yes DB2 hibernate hibernate hibernate hibernate MySQL connection connection connection connection Y no N dialect org hibernate dialect DB2Dialect hibernate driver_class COM ibm
21. T Murata Petri nets Properties Analysis and Applications Proceedings of the IEEE 77 4 541 580 1989 M Pesic H Schonenberg and W M P van der Aalst DECLARE Full Support for Loosely Structured Processes In M Spies and M B Blake editors Proceedings of the Eleventh IEEE International Enter prise Distributed Object Computing Conference EDOC 2007 pages 287 298 IEEE Computer Society 2007 J L Peterson Petri net theory and the modeling of systems Prentice Hall Englewood Cliffs USA 1981 A Rozinat M Wynn W M P van der Aalst A H M ter Hofstede and C Fidge Workflow Simulation for Operational Decision Support Using Design Historic and State Information In M Dumas M Re ichert and M C Shan editors BPM 2008 volume 5240 of Lecture Notes in Computer Science pages 196 211 Springer 2008 N Russell W M P van der Aalst and A H M ter Hofstede Workflow exception patterns In E Dubois and K Pohl editors Proceedings of the 18th International Conference on Advanced Information Systems Engineering CAiSE 06 volume 4001 of Lecture Notes in Computer Science pages 288 302 Luxem bourg Luxembourg 2006 Springer N Russell W M P van der Aalst A H M ter Hofstede and D Edmond Workflow resource patterns Identification representation and tool support In O Pastor and J Falcao e Cunha editors Proceedings of the 17th Conference on Advanced Information Systems Engineering CAiSE 05 volume 3520 of
22. W Figure 7 56 Administration Tasks Screen detail The class code is split into four sections e Header e Execute Method e Function Definitions and e Implementation To successfully add a function these rules must be followed 1 Create the function i e a normal Java method definition and add it to the function definitions section of the code Ensure the function e is declared with the access modifier keywords private static and e returns a value of String type 2 Add the function s name added to the array of _functionNames in the header section of the code 3 Add a mapping for the function in the execute method using the examples as a guide Once the function is added it can be used in any rule s conditional expression Let s use the maz function as a simple example walkthrough to be read in conjunction with the source code for the class The first thing to do is define the actual function in the function definition section The entire function is shown in Figure 7 57 Notice that the function has been declared as private static and returns a String value Next the name of the function maz has to be added as a String value to the _functionNames array in the header section of the code see Figure 7 58 Finally we need to map the function name to the execute method which acts as the interface between the class s functions and the Worklet Service The execute meth
23. detail 7 6 Walkthrough Using the Worklet Service The worklet repository that comes with the Worklet Service release contains a number of example specifi cations with worklet enabled tasks each with an associated rule set and a number of associated worklets This section will step through the execution of several of these examples The first two examples feature the Selection Service the remainder the Exception Service Knowledge of how to use the YAWL system is assumed Before we begin make sure the Worklet Service is correctly installed and operational and then log into the YAWL system 7 6 WALKTHROUGH USING THE WORKLET SERVICE 173 A Selection Worklet Enabled Atomic Task Example The Casualty Treatment specification used in the previous sections of this manual is an example of a speci fication that contains an atomic task called Treat that is worklet selection enabled We ll run a complete instance of the example specification to see how worklet selection operates Log on to YAWL with a user that has administrator or can manage cases privileges Navigate to the Case Mgt page and upload the Casualty Treatment specification from the worklets folder of the worklet repository Then launch a Casualty Treatment case from the same page The case begins by requesting a patient id and name just enter some data into each field then click Submit Figure 7 29 starting an Instance of Casualty_Treatment 123456 i v
24. for a detailed explanation of the concepts behind this approach to verification 4 9 Automated task Any atomic task in YAWL that is associated with the Resource Service i e the default association if the task is not explicitly associated with another service can have its decomposition defined as manual or automated A task with a manual decomposition is a task that is intended to be executed by a human resource e g a participant in the Resource Service s organisational model A task with an automated decomposition is 86 CHAPTER 4 THE EDITOR Configure Specification Analysis Reset Net Analysis WofYAVWL Analysis Use the WotYAWL analysis algorithm Structural check for relaxed soundness in a bounded analysis net Behaviourial check for semi positive transition invariants in a short circuited analysis net These tests may overlap in identifying unreachable tasks in the specification potential deadlocks and possible unfinished work in completed workflow cases Extend coverability graph of an unbounded analysis net slow Figure 4 46 Verification using wofYAWL a task that is not offered to any resource but is executed by the system This type of task can be used to manipulate the content of net variables from simple data assignments to complex reports generation Alternately it may be associated with a codelet a discrete piece of code that is executed optionally using the input variables of the task and assigning
25. gt lt xs element name GivenName type xsistring gt lt xs element name Address type xs string gt lt xS 2 Sequence gt lt xs complexType gt lt xs schema gt r Done if Cancel _Cancel Figure 8 10 Data Definition for Document type Set Custom Form URI Custom Form URI localhost 8080 digitalSignature Si Figure 8 11 Custom Form dialog in YAWL Editor 8 5 1 How to use the Service First please make sure that you have the mailSender war file deployed in your tomcat webapps folder The Mail Sender Service uses a YAWL custom form for sending a simple mail notification You just need one task and set the custom form of that task to call the Mail Sender jsp file First create a net that will use the 206 CHAPTER 8 OTHER SERVICES Update Task Decomposition Sign Document Extended Attributes 1 Task Decomposition Label Sign Document Task Decomposition Variables Name Type Usage Create Signature Input amp Output Document Document Input Only Update Remove YAWL Registered Service Detail YAWL Service External Interaction Automated Set Codelet Done Cancel Pa oa Pollo od Figure 8 12 Task variables for the Sign Document task Mail Sender Service Figure 8 14 Note that you don t need to create a variable to use the Mail Sender but the task that uses it will need at least one varia
26. if there are any rules of that type defined for the case and if so if any of the rules evaluate to true using the contextual data of the case or workitem If the rule set finds a matching rule for the exception type and data an exception process is invoked Note that for each of the constraint events an exception process is invoked for a rule when that rules condition evaluates to true So for example if the condition of an I temPreConstraint rule for a Triage task was PrivateInsurance false and that value of that attribute in the workitem was also false then the exception process for that rule would be invoked Externally Triggered Types Externally triggered exceptions occur not through the case s data values but because something has hap pened outside of the process execution that has an affect on the continuing execution of the process Thus these events are triggered by a user depending on the actual event a particular handler will be invoked There are two types of external exceptions CaseExternalTrigger for case level events and ItemEx ternalTrigger for item level events See later in this section for examples of each and how they are invoked 154 CHAPTER 7 THE WORKLET SERVICE TimeOut A timeout event occurs when a workitem has an associated timer or is linked to the deprecated Time Service and the deadline set for that workitem is reached In this case the Engine notifies the Worklet Service of
27. it will activate each outgoing flow that has its condition evaluate to true or the designated default flow if none of the other flows evaluate to true By adding a join to a task you are specifying at what point the task will become available for execution through the completion of one or more preceding tasks flowing into it depending on the type of join Below are possible choices for a task s join decorator e No join The task has no join decorator and so will have exactly one incoming flow e AND join The task will activate only after each and every incoming flow is activated through the completion of the task at the other end of each flow e XOR join The task will activate as soon as one incoming flow is activated through the completion of the task at the other end of the flow e OR join The task will activate only after each and every incoming flow that can possibly be activated has activated Basically this means the completion of each and every task at the other end of a flow leading into the OR join that has started or may possibly start at some future time More on the OR join in later sections For more detailed information on join and split types please consult the YAWL technical papers on the YAWL website Creating Splits and Joins To create a split or join 1 Select a task When a single task is selected the Decorator panel will appear with two tabs that allow you to decorate a task with a split and or join
28. matches the task s output parameter in Figure 4 36 Aggregate Query puts all the instance query results into a list in this case a list of order elements ready for mapping back to the net level variable The aggregate query will look exactly like this in most cases d is used simply to differentiate it from e in the splitter query but its 4 5 ADDITIONAL SPECIFICATION FEATURES 7 60o8e Multiple Atomic Task Verify List Instance Detail Multiple Instance Variable book HH Accessor Query List Builder MasterList Splitter Query for e in MasterList return lt book gt Se lt book gt Instance Query lt order gt Verify list book lt order gt Aggregate Query for d in Verify list return d Result Net Variable MasterList HH Create Done Cancel i TE EET Figure 4 37 Set Instance Detail dialog Queries tab for MI task Verify List name is unimportant Result Net Variable this specifies the net level variable to which the results of the aggregate query is to be mapped When this specification is executed it will first allow the user to specify a number of book orders then will split the details of each into a corresponding number of MI task instances one for each order The price and availability of each order can be updated within its own task instance When all or the threshold of MI task instances have
29. skipSchemaValidation boolean From the Editor the user can visualise and edit the list of attributes by selecting the tab Extended At tributes from one of the following dialog windows e Update Task Decomposition e Update Net Variable e Update Task Variable Figure 4 57 shows the rendered list of attributes for the above property file Note that attributes can only be specified through property files and not via the above dialogs Editor Troubleshooting The YAWL Editor is not responding to my mouse clicks and it is beeping every time I click the mouse Check to see if you have any Editor dialogs open To do so in Windows hold down the ALT key for OSX hold down the Command key and press the TAB key until you reach the dialog window then let go of the 4 13 EXTENDED ATTRIBUTES 97 keys Close the offending dialog window to reenable use of the YAWL Editor I can t connect two elements with a flow Why The Editor will not allow you to connect one element to another where such a connection is invalid Typical examples include e Trying to connect a second flow to an undecorated task e Trying to point an incoming flow to a split decorator or an outgoing flow from a join decorator See the troubleshooting entry How do I find out more about elements and principles for more details When I validate my Net I get the following validation message The net may complete without any ge
30. then release the mouse For a conclusion to be valid and thus allowed to be saved there must be a direct unbroken path from the start node to the end node the start and end nodes are always displayed on the canvas Also the conclusion will be considered invalid if there are any nodes on the canvas that are not attached to the sequence when Save is attempted 172 CHAPTER 7 THE WORKLET SERVICE Use the Select Tool to move placed primitives around the canvas First select the Select Tool in the toolbox then click and drag a primitive to a new location The Align button will immediately align the nodes horizontally and equidistantly between the start and end nodes as in Figure 7 27 The Clear button will remove all added nodes to allow a restart of the drawing process The Cancel button discards all work and returns to the previous form The Save button will save the conclusion and return to the previous form as long as the sequence is valid To delete a primitive from the canvas right click on the primitive and select Delete from the popup menu The Compensate primitive will when invoked at runtime execute a worklet as a compensation process as part of the handling process To specify which worklet to run for this sequence right click on the Compensate primitive and select Define Worklet from the popup menu The Choose Worklet dialog will appear identically to the Selection conclusion process allowing the selection
31. 3 Twitter Service The Twitter Service is a simple service that provides for the posting of status updates i e tweets to Twitter When a task is associated with Twitter Service in the Editor s Task Decomposition dialog the service will supply four required variables e status The message text to send to Twitter e userid A valid Twitter user account name e password The password for the nominated Twitter account and e result A response message received from Twitter that indicates the success or failure of the status update When invoked at runtime the Twitter Service will connect to Twitter through its API using the specified userid and password post the status update if connection was successful and put Twitter s response text in the result variable 8 4 Digital Signature Service The purpose of the digital signature is not to hide the data on the form captured as an XML ComplexType but to ensure the authenticity of the information This custom service is composed of two functions the first 200 CHAPTER 8 OTHER SERVICES one is to sign the XML form and the second one is to check the validity of the signature created by the first one 8 4 1 Signing a Document 1 The Document is hashed with a hashing algorithm to encrypt it and to reduce its volume 2 The Private Key is extracted from inside the key store certificate p12 To do this we need the publisher s password which is only known by him her
32. Credit Requirements Gi Task Icon Extended Attributes aa a Manual Task Decomposition Label MAGU e E TE gt T Automated Task Decomposition Variables Routing d y Plugin gt K Name Type Usage Create Receive and ApplicationID string Input Only Validate ApplicationAmount double Output Only Pr Update Application z F 5 5 Z Bo gee Remove YAWL Registered Service Detail YAWL Service Default Engine Worklist 4 External Interaction C Automated Set Codelet Select a number of net elements to manipul Done Cancel Figure 3 11 Establishing Parameters on a Task Decomposition SSS YAWL 2 0 Edit Work Item oO kas gt gt I x a aut E Eh http localhost 8080 resourceService faces dynForm jsp a 3 Cls Google Edit Work Item 2 3 The value 5000 dollars is not valid for field ApplicationAmount This field requires a value of double type Figure 3 12 A Determine Credit Requirements work item shown on a dynamic form Attaining an application amount may be as trivial as reading the number from the relevant form or as 3 4 ADVANCED WORKFLOW CONCEPTS 30 involved as considering the business s current risk exposure running calculations and adjusting the figure to something the insurance company is more willing to accept The exact nature of the work to be done is left to the participant and th
33. Data at the higher level needs to be split over the instances and after completion of the instances aggregated to data elements at the higher level 2 A set of four types of XQueries may be used to pass multiple instance data between different levels These are the accessor query for manipulating the overall multiple instance data before the unique values are split out to individual execution instances the splitter query for separating the unique values from the overall multiple instance data and passing a unique value to each instance the instance query for transforming the XML document returned on completion of an instance to a form that is suitable for aggregation and the aggregate query for finally generating an overall result and passing the result to the higher level on completion of the multiple instance task In Chapter 4 Section 4 5 9 illustrates how to specify multiple instance data manipulation e g the four types of XQueries in the YAWL Editor 104 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL 5 5 Illustrative Examples Below are three illustrative examples which cover the aforementioned data perspective of YAWL The first example is a revised version of the Credit Rating Process taken from the Oracle BPEL Process Manager Quick Start Guide 10g Release 2 May 2005 The next two examples are the first two Make Trip Processes that can be found in 2 5 5 1 Example 1 Credit Rating Process This is a simple
34. Org Group Carrier Department v Warehniice clerk Figure 6 7 The Positions tab page aia Figure 6 8 Org Data Form Tool Buttons At any time backed up org data can be re imported by clicking on the Import button You will be prompted for the file to import via an Import File panel that will appear on the bottom of the form Browse to the file then click the Import button Existing data is not removed importing data will append new data and update existing data A message describing the effects of the import will be displayed on completion 6 3 5 Managing Users Though the User Mgt Screen see Figure 6 9 an administrator can add participants and change details and privileges for existing participants The User Mgt Screen consists of four panels top left shows the participant s personal details name password userid and so on top right allows the setting of user privileges see below bottom left allows the assigning of the participant to various roles positions and capabilities and bottom right is where the participant s password can be reset There are many similarities between the User Mgt and Org Data Mgt Screens regarding the addition modification and removal of items e To View an existing participant s details select the participant s name from the Participant dropdowm list e To Add a new participant click the New button which will disable the dropdown and activate all other fields
35. Service The Treat task simulates that part of the process that follows the collection of patient data and actually treats the patient s problem Of course there are many medical problems a patient may present with and so there are just as many treatments and some treatment methods are vastly different to others In a typical workflow process this is the part of the process where things could get very complicated particularly if we tried to build every possible treatment as a conditional branch into the process model The Worklet Service greatly simplifies this problem by providing an extensible repertoire of discrete workflow 174 CHAPTER 7 THE WORKLET SERVICE Edit Work Item 1 1 compat Figure 7 30 Editing the Admit Workitem detail processes worklets which in this example each handle the treatment of a particular medical problem By examining the case data collected in the earlier tasks the Worklet Service can launch as a separate case the particular treatment process for each case This method allows for a simple expression of the task in the parent process i e a single atomic Treat task signifies the treatment of a patient whatever the eventual treatment process may be as well as the ability to add to the repertoire of worklets at any time as new treatments become available without having to modify the original process When the Triage workitem is submitted the next task in the process Treat beco
36. You can also choose a fill colour to help visually differentiate splits from joins with the expanded colour palette 50 CHAPTER 4 THE EDITOR Choose the required split or join and the orientation which edge of the task to attach the decoration to for the split or join to appear In our example select the Begin My Career task and in the Decorator panel select an XOR split Then set the orientation to eastern edge of the task as per Figure 4 8 Create a new Atomic task called Do Private Study This task will represent those students that choose not to go to University Finally select your Get A Job task and decorate it with an XOR join Then set the orientation of the join to the western edge of this task Split and Join decorators allow you to connect several Flow Relations from and to your task respectively Create a flow relation from Begin My Career to Do Private Study then create another flow relation from Do Private Study to Get A Job as per Figure 4 8 Career Started Go to University Begin My Career Do Private Study Figure 4 8 XOR Split and Join 4 Don t forget to check the validity of your specification Hint If you are having trouble with positioning your tasks the alignment tools are a big help When Begin My Career has been completed a choice must be made on which of the two tasks Go To University or Do Pri
37. adamsmj Documents research temp myCareer yawl ADopann am jeja m tu ejs a mw e aea reer L Study_Privately I Attend_University P H Task Icon Begin My Attend Get a Job Career No Icon Career University Started gt O Manual gt lt lt Automated b 4 Routing J Plugin Study Privately No design time engine validation problems were found in this specification Left click on the selected net to create a new atomic task Figure 4 41 A valid specification To save your specification to file 1 Click on the Save button Bl on the Menu Toolbar or click Specification on the Menu and choose Save Specification The Specification File Save Options dialog appears Figure 4 43 If this is the first time the specification has been saved and a Specification ID has not yet been entered via the Update Specification Settings dialog a Specification ID field will appear in the dialog all Specifications must be given a valid ID The ID can be a combination of alphanumeric characters and the underscore but cannot start with a numeric character Once set this field will not reappear in subsequent saves of the specification The Version Number field provides a version number for the specification Version numbering al lows different versions of the same specification to co exist in the Engine YAWL specification version 82 CHAPTER 4 THE EDITOR YAWLEditor
38. additions for the session Save amp Close returns to the main form and saves all additions 7 5 8 Drawing a Conclusion Sequence As mentioned in the Adding a New Rule section adding a conclusion to a Selection rule is simply a matter of choosing a worklet from the list or creating a new worklet in the YAWL editor However when adding a conclusion for a rule type other than Selection i e an exception rule type an exception handling sequence needs to be defined that will manage the handling process invoked by the rule The earlier section on the Exception Service detailed the various actions that make up the available set of exception handling primitives or tasks that may be sequenced to form an entire handling process The Draw Conclusion dialog makes the process of defining an exception handling sequence easier by allowing you to create the sequence graphically Simply select the appropriate primitive from the toolbox on the left and then click on the drawing canvas to place the selected primitive Figure 7 27 shows an example of the Draw Conclusion dialog Toolbox Canvas a Worklet Rules Editor lt New Conclusion gt 4 B Select Arc Start End Tool Tool Node Node Figure 7 27 The Draw Conclusion Dialog Use the Arc Tool to define the sequence order First select the Arc Tool in the toolbox then click and hold on the first node drag the mouse pointer until it is over the next node in the sequence
39. after choosing the from expression radio button This choice is only available for automated tasks and any task variables used in the XQuery expression itself must be declared as Input amp Output usage types 4 9 1 Codelets Essentially a codelet is a discrete Java class managed by the Resource Service that may be enacted by an automated task at runtime When an automated task is enabled during process execution and it has a 4 9 AUTOMATED TASK 87 9O09 Update Net Parameter PO_timedout F 7 ce _ from element of task variable add XQuery of element s content O trom expression A add XQuery of entire element XQuery lt PO_timedout gt Erue lt PO_timedout gt Done Cancel Figure 4 47 An output parameter set to copy from expression for an automated task codelet associated with it the input parameters of the task are passed to the codelet it is executed and any results are passed back to the task via its output parameters There are currently three codelets available in the Editor see the YAWL Technical Manual for directions on how to add user defined codelets e ExampleCodelet designed to demonstrate the usage of codelets e XQueryEvaluator accepts an XQuery as an input parameter evaluates it using other input parameters as required by the XQuery and produces the result to an output parameter e ShellExecution accepts an input parameter containing a command line of an external program a
40. an operation of a SOAP web service at design time and at runtime task instances are routed to the specified SOAP web service through the WSInvoker Without this layer a Custom Service would have to be developed between each and every SOAP web service and the Engine on an individual web service basis A task is associated with WSInvoker by opening the Task s Decomposition dialog in the Editor and choosing the WSInvoker from the list of available services Figure 8 1 The service will supply to the task three variable definitions which will require supplied values when the service is invoked at runtime e Yaw lWSInvokerWSDLLocation specifies the URI of the WSDL file describing the web service to invoked e Yaw lWSInvokerPortName specifies the port binding that the web service listens on for interaction with external clients and protocols and e Yaw lWSInvokerOperationName specifies the name of the operation to be executed within the web service In addition any data values that are required for the web service s operation must also be specified within the task decomposition these are passed to the specified web service when it is invoked The WSInvoker Service then waits until the external service responds then returns a mapping of the resultant data to the task instance s output data parameters Note that when a task is registered with the Invoker Service at design time the Editor automatically populates the task s inpu
41. and the Resource Service required for certain design activities discussed later in this chapter A connection will show a green indicator a disconnection as a red indicator e Next there is a status message area that provides useful contextual hints throughout the creation of your specification e On the right is a progress bar which shows the progress of various events at different times 4 3 Creating Your First Specification Overview This section will lead you through the process of creating a YAWL specification from beginning to end through a series of brief lessons following a scenario You can either follow all the instructions including the scenario provided from beginning to end or skip straight to the section that you are interested in and follow the instructions Look for the student icon next to the instructions for specific details of the scenario The Scenario The scenario that we will be following throughout this section is the workflow of a student who has just completed their secondary study and is now looking to start their career The scenario will follow the path of a student who either enrols in a University to complete their tertiary education or undertakes private study that will eventually lead them to getting a job and starting their new career 4 3 1 Creating Your First Specification 1 Click on the Create a New Specification button Bl at the top left of the Menu Toolbar or click on Specification
42. before the user commits to using those details for any further editor engine interactions 4 6 2 Connecting to the Resource Service To use the organisational data managed by the Resource Service for assigning tasks to Participants or Roles a connection between the editor and the Resource Service needs to be established Like the Engine connection above when the Editor starts a connection to a running Resource Service is attempted If successful the Resource Service connection icon at the left of the status bar will turn green If unsuccessful perhaps because the Service is not running or the connection parameters are incorrect the connection icon will show red After the Editor has started a Resource Service connection may be performed via the Tools menu To set the Resource Service connection details 1 Click on the Tools menu and choose the Resource Service Connection Settings item 80 CHAPTER 4 THE EDITOR 2 From the resulting dialog Figure 4 40 accept the default values or enter the following engine details e YAWL Engine URI e Administrator s User Name e Administrator s Password AA Resource Service Connection Settings Resource Service URI http localhost 8080 resourceService gateway User Name admin Test Connection Password Successfully connected to a running resource service Done Cancel Figure 4 40 Specifying the Resource Service connection The Resource Engine valu
43. by the User and not by the System at runtime an Administrator will need to manually choose the resource s to offer the work item to If System offering is chosen then in Steps 2 and 3 we can specify the resources that will automatically be offered work items of the task at runtime If we choose that work items are to be Allocated by the User and not by the System any participant who has been offered the work item can manually choose whether to commit to being responsible for the performance of the work item i e to allocate the work item to themselves If System allocation is chosen in Step 4 we can specify how work items will be allocated to a participant by the System If we choose that work items are to be Started by the User and not by the System then the user will choose to manually start working on the work item at a time of their choosing If System starting is chosen the work item once it is allocated to the participant will be immediately started 4 10 RESOURCE MANAGEMENT MANUAL TASK 89 a ee Manage Resourcing Wizard for Atomic Task Receive and Validate Application Step 1 Choose Behaviour At Interaction Points There are three key decision points for managing the resourcing of work items spawned from a task At each of these interaction points you may choose to have the system dynamically make a decision on resourcing at each point or alternately allow a user to manually make each decision Each interaction point is br
44. can be found at www w3schools com xquery default asp and www xquery com developers 4 5 ADDITIONAL SPECIFICATION FEATURES 69 689A Update Parameters for Atomic Task Enrol Input Parameters Task Variable Create A Upd ate ap Remove Task Variables Name Type Usage StudentNumber Input amp Output Sub jectcode string Input amp Output Net Variables Name Type StudentNumber string SubjectCcode string Output Parameters Net Variable Create Update hd Remove Done Figure 4 30 Updating Parameters for a Task box will appear Figure 4 30 Update the Parameters for the Enrol task Notice that the dialog in Figure 4 30 lists both this task s variables and the variables of its containing net 3 In the Input Parameters section click on Create An Update Task Parameter dialog box will appear If you have already set up a Task Variable for this task then the Existing Task Variable option will be activated and there will be a list of task variables to choose from Choose a variable from the list and click on Done then Done again to close the task parameters dialog If you haven t set up Task Variables then click on Create and return to the previous section dealing with Task Variables Section 4 5 7 If you are familiar with XQuery syntax then you can add an XQuery expression to allow manipulation of the Input Parameters Syntactically well formed XQueries will be gree
45. clicking on the Net Menu and choosing Update Net Detail We are going to call this new Net Attend University Return to your original Net and right click on your Composite Task and choose Unfold to net You will then be given a drop down list with all the Nets available choose the Net this task is to represent and then click Done Tip you can also combine the last three steps by simply right clicking on the newly added composite task selecting Unfold to net then clicking the Create button in the dialog that appears Choose Attend University You can now fill out the detail of your new Attend University Net Create the following Atomic Tasks in order and then link them with Flow Relations and don t for get to check for validity e Enrol e Do Subjects e Pass All Subjects e Get Degree The resulting nets are shown in Figures 4 9 and 4 10 _ Attend University Attend University Get a Job Career Started Begin My Career Do Private Study Figure 4 9 Parent net with Attend University Composite Task 4 3 3 Multiple Instance Atomic Tasks Multiple Instance Atomic Tasks MI Tasks allow you to run multiple instances of a task concurrently To create a Multiple Instance Atomic Task 52 CHAPTER 4 THE EDITOR My Career Do Subjects Pass All Get Degree Subjects Figure 4 10 The Attend University sub net 1
46. completed their data will be aggregated back into the list for display in the third and final task When the instance creation type is set to dynamic then new instances of the MI task may be created at runtime after the task execution has begun and split into its instances There is a button on the default worklist handler to accommodate this see Chapter 6 which will be enabled for dynamic MI tasks until such time as the maximum instances bound has been met 18 CHAPTER 4 THE EDITOR 4 5 10 Fast Tracking Data Definition If all of a task s input and output parameters will involve a simple mapping to and from net level variables a fast track can be taken to do it all in a few mouse clicks To achieve this right click on an atomic task that does not yet have a decomposition and select Decompose to Direct Data Transfer The dialog in Figure 4 38 will appear 8 O88 Atomic Task Select a number of net variables to be used as input to this task Do the same for output The selected net variables will have type compatible task variables of the same name created for them and mappings that will enact a direct data copy between the newly created task variables and the specified selected net variables Decomposition name Enrol in Subject Net Variables for Input Net Variables for Output Name Name Type Wi StudentNumber string Ki SubjectCode string Done Cancel amp FF i Figure 4 38 An example of the direct d
47. engine which then progresses the case according to its control flow This action is initially disabled if the work item contains mandatory editable data variables as in Figure 6 14 and becomes enabled after the first view edit of the work item 6 4 4 The Suspended Queue The Suspended queue lists executing work items that have been suspended via the Suspend button on the Started queue Note that suspended work items must have already been started and not yet completed and so this queue may be seen as an extension of the started queue This queue contains one action Unsuspend which resumes the work item removing it from the suspended queue and returning it to the started queue 6 5 USER PROFILES 137 Sires soree Specification Task 49 1 Create_Book_List_4 Emergency Assess affected area 50 1 Assess cS affected_area_3 2 1 1 Create_Purchase_Order_104 Case Status 50 1 Suspended Created Age dJul 23 2009 12 3727 0 03 18 03 Figure 6 16 The Suspended Work Queue 6 5 User Profiles Piled Tasks Emergency Assess_affected_area_3 Roles Supply Admin Officer gt Positions Assistanthead of OD v Capabilities Master s in SCLM z v Administrator Change Password New Confirm Figure 6 17 The Edit Profile Screen The Edit Profile screen consists of four panels Figure 6 17 e A Personal Information panel where a participant can see their name userid lists of their roles positions an
48. expression for choosing the branch of Book Car at task Decide 1 Only net variables are allowed to be used in specifying flow predicates This is because the flow evaluation for a task with XOR or OR split is conducted after completing the execution of the task and therefore the task variables are no longer available 2 Similarly to the XQuery validation the syntax validation of XPath expressions can be performed in the YAWL editor The semantics validation is however a different matter As YAWL applies only XPath boolean expressions for specifying flow detail an XPath boolean expression with invalid semantics may evaluate to false and as a result the execution of the process will still continue In such a case designers need to validate their YAWL specification against the desired system behaviour by themselves 5 4 2 Multiple Instance Data There are two categories of data associated with multiple instance tasks One is the task attribute data which define the maximum and the minimum number of instances allowed as well as the threshold value The other is the multiple instance data which are specific to individual execution instances of tasks within a single workflow case 18 Below we describe how to handle multiple instance data in YAWL YAWL supports both the designated multiple instance tasks and the isolation of data elements between task instances However the handling of multiple instance data is far from trivial
49. function converts the String passed into the function to a JOOM Element and then extracts from that Element a value for status being one of the data attributes contained in the this variable It then calls another method defined in the Implementation section called isFinishedStatus see Figure 7 62 private static boolean isFinishedStatus String status return status equals WorkItemRecord statusComplete status equals WorkItemRecord statusForcedComplete status equals WorkItemRecord statusFailed Figure 7 62 Definition of method isFinishedStatus All methods defined in the Implementation section must also be declared as private static methods however they can have any return type so long as the value returned from the execute method back to the Worklet Service has been converted to a String value Of course you are not restricted to querying the this variable as a WorkItemRecord it is passed simply as a JDOM Element that has been converted to a String and so can be queried via a number of different methods The objective of the RdrConditionFunctions class is to allow developers to easily extend the capabilities of the Worklet Service by providing the means to test for other things in the conditional expressions of rule nodes other than the process instance s data attributes and values It is envisaged that the class s functions can be extended into areas such as process mining querying resource lo
50. is done by decorating the task with a join A similar situation holds when a task has multiple outgoing flows In this case we need to decorate the task with a split 3 3 BUILDING A SIMPLE WORKFLOW EXAMPLE 27 808 YAWLEditor Bolo NN B b Task kon sche Determine gt G selon Credit Large Credit ie Diii Requirements Approval P g Routing 4 Plugin m Choose g approva i Process Receive and Validate Obtain Application Credit Report Small Credit Approval Left click on the selected net to create a new atomic task Figure 3 2 Atomic Tasks Added to the Starting Net Figure 3 3 lists the available joins and splits that can be used on tasks along with a brief description of the behaviour to expect from tasks when using them Returning to our example the tasks Receive and Validate Application and Choose Approval Process both require decoration The first of these two tasks requires an AND Split because the subsequent tasks can be done in parallel The second task should have an XOR split decorator to signal that either of the subsequent tasks should be performed but not both With these splits and joins in place we can now connect the remaining tasks as depicted in figure 3 4 We now need to say how information passes from YAWL to its participants e g workers and external applications and how information comes back into YAWL once they re finished This is done by attaching a decompos
51. is complete and the last true node returns its conclusion 7 6 WALKTHROUGH USING THE WORKLET SERVICE 183 Edit Work Item 8 2 Save Complete Figure 7 44 The Sell Tickets Workitem detail Effective Composite Aule If TicketsSold lt Seating 0 75 then suspend workiten run worklet Change oMidvenue continue workitem except it TicketsSold lt Seating 0 5 then suspend workitem run worklet Change T oSmallvenue continue workitern escept if TicketsSald lt Seating 0 2 then suspend case run worklet Cancels how remove case Figure 7 45 Effective Composite Rule for Do Shows Pre Item Constraint Tree The result of all this can be seen in the Work Queues screen of the worklist The Do Show workitem is marked as Suspended and thus is unable to be selected for starting while the ChangeToMid Venue worklet has been launched and its first workitem Cancel Stadium is enabled and may be started By viewing the log file you will see that the ChangeToMid Venue worklet is being treated by the Exception Service as just another case and so receives notifications from the Engine for pre case and pre item constraint events also Start Cancel Stadium accept the default values and complete Notice that the worklet has mapped the data attributes and values from the parent case Next start the Book Ent Centre workitem by default it contains the data values mapped from the parent case Since we are moving the concert t
52. it and so is no longer available for selection on the New Rule form e If it is an item level tree the task name that the tree represents will be removed from the Task Name list That is the task now has a rule tree defined for it for the selected rule type and so is no longer available e If it is an item level tree and all tasks now have trees defined for them for the selected rule type i e this was the final task of the specification for which a tree has been defined the rule type that the tree represents will be removed from the Rule Type list This approach ensures that rule trees can only be added where there are currently no trees defined for the selected specification Once the tree is added the form resets to allow the addition of another new tree as required by repeating the process above for a new rule type or rule type task name for item level trees 7 5 WORKLET RULE SETS AND THE RULES EDITOR 171 After you have completed adding trees click the Save amp Close button to save all the additions to the rule set file The Rules Editor will return to the main form where the additional trees will immediately be able to be browsed IMPORTANT No additions will be actually saved until the Save amp Close button is clicked this is to allow you the option to discard all additions if you wish by clicking the Cancel button That is cancelling returns to the main Editor form and discards ALL
53. lt order gt lt title gt YAWL User Manual lt title gt lt price gt 0 00 lt price gt lt inStock gt false lt inStock gt lt order gt When entered correctly the text will become green to show that it is a valid value to assign to the Masterlist variable of complex type BookList since it defines values for the elements of one BookO rder It is important that an initial value is provided for this variable because our definition of the BookList type specifies that it will contain at least one element that is because it doesn t include a minOccurs 0 clause If there was no initial value specified for this type the specification would fail schema validation at runtime in other words the Engine will reject the specification e Add a decomposition to the first atomic task and call it Create Book List Add to the decomposition a variable called bookList of type BookList and usage Input amp Output Then open the Update Parameter Mappings dialog add an input parameter mapping the net level Masterlist variable to the task s bookList variable and an output parameter to map it back again see Figure 4 35 This task will allow a user to add any number of book orders to the master book list e Add a decomposition to the other atomic task and call it Show List Add a variable to the decom position similarly to the first task except that the usage should be Input Only and so only an input par
54. name gt lt param value gt true lt param value gt lt description gt set this value to true to enable monitoring by an Exception Service specified by the URI param below set it to false to disable the Exception Service lt description gt lt context param gt Figure 7 3 The YAWL Engine s web xml file detail lt This param when available enables the worklet exception service add ins to the worklist If the exception service is enabled in the engine then this param should also be made available If it is disabled in the engine the entire param should be commented out gt a a lt context param gt lt param name gt InterfaceX_BackEnd lt param name gt lt param value gt http localhost 8080 workletService lt param value gt lt description gt The URL location of the worklet exception service lt description gt lt context param gt gt Figure 7 4 The Resource Service s web xml file detail The Exception Service is now fully enabled and operational For information on how the Exception Service works and how to use it see Sections 7 3 and 7 6 Installing the Rules Editor The Worklet Rules Editor allows you to browse the rule sets of specifications add new rules to existing rule sets and add complete new rules trees to rule sets It is a NET based application so has the following requirements e Operating System Windows OSs 98SE or better e The Microsoft NET framewo
55. of an existing worklet or the definition of a new worklet to run as a compensatory process Select the appropriate worklet to add it to the compensatory primitive Note that a sequence will be considered invalid if it contains a Compensate primitive for which a worklet has not yet been defined The primitives SuspendAllCases RemoveAllCases and ContinueAllCases may be limited to ancestor cases only by right clicking on primitives of those kinds and selecting Ancestor Cases Only from the popup menu Ancestor hierarchies occur where a worklet is invoked for a case which in turn invokes a worklet and so on When a primitive is limited to ancestor cases it applies the primitives action to all cases in the hierarchy from the current case back to the original parent case rather than all running cases of the specification IMPORTANT No validation is done for the defined sequence besides that described above It is up to the designer of the sequence to ensure it makes sense for example that it doesnt try to continue a case it has previously removed When a valid sequence is saved you will be returned to the previous form i e either the Add Rule or New Rule form depending on where you are in the Editor The conclusion will be displayed textually as a sequential list of tasks Figure 7 28 for example Conclusion 1 suspend workiterm A mn worklet SendAemrnder 3 continue workiem Figure 7 28 A Conclusion Sequence shown as Text
56. of an item level rule type will contain one rule tree for each task of the specification that has rules defined for it not all tasks in the specification need to have a rule tree defined e Rule Set a set of one or more tree sets representing the entire set of rules defined for a specification Each rule set is specific to a particular specification A rule set will contain one or more tree sets one 158 aijee Condition not satistied S Froti ime TreatF racture Aash fe Tre ath ash f Heatfaie 720 TreatHighHeartR ate ri Wow ue 3 AhdowminaPanr lime CHAPTER 7 THE WORKLET SERVICE a i we condition r a default 5 conclusion a ee 1 Condition satistied T Pregnant frre TreatLabour S Figure 7 12 Example Rule Tree Casualty Treatment spec for each rule type for which rules have been defined Of course to maintain a rule set of any complexity by directly editing the XML in a rule set file would be daunting to say the least To make things much easier a Rules Editor tool has been developed and can be found in the rulesEditor folder of the worklet repository It can be run directly from there no further installation is required depending on the requirements below 7 5 2 The Rules Editor The Worklet Rules Editor allows for the addition of new rules to existing rule sets of speci
57. of the use of this environment can be found in the remainder of this user manual while there is also a technical manual for those that want to develop more complex applications A number of case studies documenting the use of YAWL are also available Mailing lists and forums around the components of YAWL can also be accessed via this Sourceforge URL And as mentioned earlier YAWL is the product of several years of research into workflow patterns and formal foundations of workflow This research along with other informative material is available via the URL http yawlfoundation org 38 CHAPTER 3 GETTING STARTED WITH YAWL Chapter 4 The Editor Before a workflow model can be executed it must first be defined This chapter describes the YAWL Editor version 2 0 a tool for creating editing validating and analysing workflow specifications New users are encouraged to read the chapter sequentially experienced users may pick and choose what they need from this chapter Figure 4 1 illustrates the interactions among some of the major components of the YAWL environment YAWL Process Editor a sual process 10del Workflow API calls specification YAWL Runtime Environment lt c XML over HTTP Figure 4 1 The YAWL Components In this chapter this icon indicates a hands on method or inst
58. onto the canvas We first need to define a complex data type to store the entire book order Open the Update Data Type Definitions dialog from the Specification menu then enter the following two type definitions lt xs schema xmlns xs http www w3 org 2001 XMLSchema gt lt xs complexType name BookO0rder gt lt xs sequence gt lt xs element name title type xs string gt lt xs element name price type xs double gt 74 CHAPTER 4 THE EDITOR lt xs element name inStock type xs boolean gt lt xs sequence gt lt xs complexType gt lt xs complexType name BookList gt lt xs sequence gt lt xs element maxOccurs unbounded name order type BookO0rder gt lt xs sequence gt lt xs complexType gt lt xs schema gt The first defines a complex type called BookOrder which is a record with three simple type fields The second defines a complex data type called Booklist which consists of an array of one or more elements called order of BookOrder type unbounded means there is no upper limit on the number of order records we can include in the book list Once this is added we can start populating the data perspective of the specification e Create a net level variable called MasterList of type BookList and usage Local Tip In the Update Variable dialog Type dropdown user defined types are listed after all the built in simple types Give the variable this initial value
59. or booted from a CDROM No installation is required Preparation Booting YAWLive from a CDROM does not work on all computers Therefore it is recom mended to start the YAWLive iso image out of a virtual machine like VirtualBox No installation of an additional operating system into the virtual machine image is necessary The virtual machine image needs to boot the YAWLive iso image only Please read the instructions of your preferred virtual machine to boot an iso image es Help YAWLi OF Right Ctrl Figure 2 10 YAWLive Welcome Boot Prompt Usage of YAWLive After showing a YAWLive Welcome screen and entering Return at the prompt see figure 2 10 the YAWLive iso image is booted as shown in figure 2 11 As soon as the desktop environment appears you can immediately start using YAWL see figure 2 12 2 5 Manual Installation If you already have Apache Tomcat version 5 5 26 or greater and or PostgreSQL version 8 1 or greater and or a previous version of YAWL you may prefer to install specific components only Alternately you may wish to use a different database back end than PostgreSQL or a different servlet container than Apache Tomcat Manual installation is also required if you want a multi user production level installation on an OS platform other than Windows This section details how to install YAWL 2 0 on a component by component basis 2 5 1 Installing Tomcat YAWL mainly consists of a number of web services a
60. parameter named Repository and change its param value to the path where you have relocated the worklet repository The value should include the folder repository and end with a slash as shown in Figure 7 2 lt context param gt lt param name gt Repository lt param name gt lt param value gt catalina base webapps workletService repository lt param value gt lt description gt The path where the worklet repository is installed lt description gt lt context param gt lt context param gt lt param name gt EnablePersistence lt param name gt lt param value gt false lt param value gt lt description gt true to enable persistence and logging false to disable lt description gt lt context param gt Figure 7 2 The Worklet Service s web xml file detail If you have enabled database persistence for the YAWL Engine if necessary see Chapter 2 Section 2 5 for details about enabling persistence for the YAWL Engine then persistence should also be enabled for the Worklet Service so that case data for running processes can be persisted across Tomcat sessions To enable persistence change the param value to true for the EnablePersistence parameter Save and close web xml Worklet Service configuration is now complete However by default the Selection Service is enabled within the YAWL Engine but the Exception Service is not If you wish to enable the Exception Service proceed to Step 3 be
61. please send your feedback to yawlmanual gmail com All suggested improvements will be incorporated into future versions of the manual Sources The first version of this document combined the following documents 1 A New Features document produced by Lachlan Aldred 2 A Getting Started with YAWL document by Lindsay Bradford and Marlon Dumas This forms the basis for Chapter 3 3 A Editor 2 0 User Manual document of which first versions were produced by Sean Kneipp and subsequent versions by Lindsay Bradford Jessica Prestedge Marcello La Rosa and Michael Adams This document was copied into Chapter 4 4 A Data Manipulation in YAWL document by Chun Ouyang with some of the figures on the use of XML technology in YAWL taken from a presentation by Lachlan Aldred This forms the basis for Chapter 5 5 A YAWL Engine User Manual Beta 8 release document created by Sean Kneipp with subsequent additions updates by Guy Redding Lachlan Aldred and Michael Adams This document provided inspiration for Chapter 6 CONTENTS 6 A The Worklet Custom Service for YAWL Installation and User Manual document created and later revised by Michael Adams Lachlan Aldred merged the installation manual This document was copied into Chapter 7 7 An Installation Manual Engine Beta 8 2 Editor 1 5 first created by Sean Kneipp and with subse quent changes corrections extensions by Guy Redding Lachlan Aldred
62. process that provides a credit rating service When running this process the client user is asked to provide his her social security number The process takes the number and returns credit rating There are two situations If the client s social security number starts with 0 a fault reporting Bankruptcy will occur Otherwise a credit rating e g 560 will be given From the above the data associated with this process are 1 client s social security number ssn 2 credit rating 560 and 3 fault Bankruptcy YAWL Specification Figure 5 5 shows the YAWL net specifying the above credit rating process There are three labelled tasks ReceiveSSN for requesting a social security number from the client ReportFault for reporting a Bankruptcy fault and DecideRating for providing the credit rating 560 There is also an unlabelled task which has an XOR join this is an example of a routing or empty task that is a task without decomposition and is used here to ensure the net is sound F Credit Rating Process gt ES DecideRating Fecevesslh ReportF ault Figure 5 5 The CreditRatingProcess net Figure 5 6 shows three net variable definitions for the CreditRatingProcess net All are defined as local variables in order to avoid any data interaction with the external environment at the net level Also both rating and fault are assigned an initial value Figure 5 7 shows the param
63. provide the document which has been signed Note that the Document variable is an anyType type to be able to check back any complex type you may have signed 8 5 EMAIL SENDER SERVICE Le CC BLANY r 2 one n ee a ai 5 m i t D ep ba mh pua y e ArH ee S De eel En m urrak T ies t O Deed a ee aE ery SS mh gt 5 bape Ci ci Seri or im CS eres D GA Eji Se oe ee ry Gi eet apa Big Go dea a ee Ti 2 Grrr i mP arria i ey ime GJ ian umd n HFA Prym THU ai TL op AH a Cet nie pagum tamer npemi eea BF oe ee F g i i E Figure 8 6 Generating the Key Pair 8 5 Email Sender Service The Email Sender Service allows users to send simple emails from within the workflow process instance 203 204 CHAPTER 8 OTHER SERVICES Pe E eee r Coit ria a i i TEETE Waid Fraai 17 pip Se TA Yahi eds iranha 17 pat T Wat ARO TO ee ei a FeO MME A n ree eo i oe ee Figure 8 7 The Created Certificate OI Peai ees ed ee a es Cyst es eae ee ee Figure 8 8 Exporting the Certificate 8 5 EMAIL SENDER SERVICE 205 Fulfil Sign Verify Document Document Signature Figure 8 9 Example YAWL Process aoe Update Data Type Definitions 4MM Sle lt xs schema xmlns xs http www w3 org 2001 XMLSchema gt lt xs complexType name Document gt TXS sequence gt lt xs element name FamilyName type xs string
64. queue or if the start interaction is system initiated the work item is immediately started and placed on the participant s started queue This action removes the work item from the offered queues of all other participants that had been previously offered the work item e Accept amp Start This action works similarly to Accept Offer except that if the work item s start 134 CHAPTER 6 THE RUNTIME ENVIRONMENT interaction is user initiated the work item will instead be immediately started and placed on the partic ipant s started queue Effectively this concatenates two user actions into one simply as a convenience for the user e Chain This action will chain all the eligible work items of the case of which the work item is a member to this participant Chaining means that when a participant chooses to enact it each remaining work item for the case is routed to the participant and immediately started but only if the participant is a member of the distribution set for the work item Chaining is effectively a short circuiting of a resource specification for a task where the participant chooses to automatically and immediately allocate and start any work item offered to him her within the chosen case Chaining of work items for a case continues until the case completes or the participant turns off chaining via the View Profile form A participant must have the Chain Work Item Execution user privilege to enable chaining 6 4 2 The
65. s timer settings To use this deferred approach 1 Create a net level parameter of type YTimer T ype 2 Choose a task right click on it and choose Set Task Timer to open the Set Timeout Detail dialog Figure 4 54 click the dynamically via net variable option and select the net level parameter created in Step 1 3 Map the net level parameter to another previous task in the flow which will be used to capture the required values from a user at runtime Those values will be used to set the timer parameters on the task selected in Step 2 The values requested are e Trigger when should the timer start There are two valid trigger values OnEnabled and OnEx ecuting e Expiry when should the timer expire This value can be either a date string for example 12 12 08 which will be interpreted as a specific moment or as a Duration value which will be interpreted as a period of time An example of how a variable of YTimerType appears in a dynamic form at runtime can be seen in Figure 4 55 Edit Work Item 6 1 Figure 4 55 Example of a YTimerType variable rendered on a dynamic form 4 12 CUSTOM FORMS 95 4 12 Custom Forms When a task is associated with the default worklist handler i e the Resource Service then at runtime the data within the task instance may be selected for viewing and or updating By default the Resource Service uses a built in dynamic forms component which generates appropria
66. set correctly returns the TreatRash worklet it may be desirable to treat the racing heart rate before the rash is attended to In such a case as the Worklet Service begins execution of an instance of the TreatRash process it is obvious that a new rule needs to be added to the rule set so that cases that have such data both now and in the future will be handled correctly To add a new rule to a particular tree of a rule set it is first necessary to open the rule set in the Rules Editor as described above Then click Rules on the top menu then Add or click the Add Rule toolbar button to open the initially blank Add Rule form Notice that the name of the opened rule set is shown in the title bar of the form and the rule type and task name that are currently selected on the main form have been transferred to the Add Rule form Thus to add a new rule to a rule tree that rule tree must first be selected on the main Rules Editor form before the Add Rule form is opened Every time the Worklet Service selects a worklet to execute for a specification instance a log file is created that contains certain descriptive data about the worklet selection process These files are stored in the selected folder of the worklet repository The data stored in these files are again in XML format and the files are named according to the following format CaselID_SpecificationlD_Rule Type WorkItemID x2ws For example 12_CasualtyTreatment_Selectio
67. since the public key is contained in the X 509 certificate It is hard to reproduce this signature as the private key is only contained in the certificate PKCS 12 and it needs the owners password to be extracted Also if the signature is slightly modified the digest function won t match the signature anymore 8 4 DIGITAL SIGNATURE SERVICE 201 SHAIL Hash Calculation Document FingerPrint Valid signature Figure 8 4 An overview of the verification of a digital signature 8 4 3 Interaction between a YAWL custom form and the service Before you can use the digital signature function the user will need to create a digital certificate These certificates are provided by a CA certificate authority for example Thawte Consulting for X 509 certificates It is advisable to use a certificate provided by a trusted third party like CA but you can also create your own certificates using some open source tools 8 4 4 Creating a New Certificate New certificates can be easily created using Key tool IUI which can be downloaded from www softpedia com get Security Security Related KeyTool IUI shtml The first step is to create an empty Key Store PKCS12 locked with your password Save the empty key store in a chosen location Figure 8 5 Then use this key Store to generate the key pair and the X 509 certificate by filling in the owner information Figure 8 6 When the key pair is created you can review the certifica
68. so there is no record of them or the way they were handled kept for future executions of the process specification The Worklet Exception Service allows for such events to be handled on system by providing a means for exceptions to be raised by users externally to the process itself The Organise Concert specification will again be used to illustrate how external triggers work Go to the Case Mgt page and launch another instance of the Organise Concert specification Execute and submit the first workitem If the Worklet Exception Service has been correctly enabled in the Resource Service two extra buttons will appear on the Case Mgt page Raise Exception and Reject Worklet To raise a case level external exception go to the Case Mgt screen and select the Organise Concert case from the list of running cases then click the Raise Exception button Figure 7 47 The Raise Case Level Exception screen is now displayed This screen is a member of a set of Worklet Service add in screens for the worklist Before this screen is displayed the Exception Service retrieves from the rule set for the selected case the list of existing external exception triggers if any for the cases specification See Figure 7 48 for the list of case level external triggers defined for the Organise Concert specification This list contains all of the external triggers either conceived when the specification was first designed or added later as new kinds of except
69. stored in HR Systems and so on External data sources may be mapped to YAWL by implementing a java class to take care of the necessary mappings see the technical manual for details This parameter allows for the specification of that mapping class name The default setting is HibernateImpl the internal Resource Service mapping class e OrgDataRefreshRate This parameter provides for the setting of a regular time interval to refresh the organisational data caches in the Resource Service This is particularly important when the org data is sourced externally and that external source is live regularly updated through other systems If an external data source is not being used then the parameter s value should be left at 1 the default interpreted as never refresh since the internal data sources are only ever updated through the web forms of the Resource Service The parameter value specifies the number of minutes to wait between refreshes e LogOffers By default all resourcing events offer allocation start reallocate etc are written to a process log If there are large numbers of participants in the organisational model or work items are typically offered to a large number of potential participants the logging of all offers may incur some processing overheads for little return e g there may be instances where a work item is offered to several hundred participants the members of that set can alw
70. task 4 5 7 Task Parameters A parameter defines how a value is assigned to a variable and how a value is passed between net level and task level variables and vice versa Both Input and Output Parameters can be assigned to any tasks depending on their usage type to allow the passing of state between nets and their tasks and between tasks and workflow engine users and web services Parameters are defined using XQuery expressions Input Parameters use an XQuery expression to specify a value possibly drawing on a number of static and or net level variable values that can be passed to a single selected task variable Output parameters use an XQuery expression to specify a value that can be passed to a single selected net variable For example if a task is called Lookup Book then an Input Parameter could pass the name of the book to a task variable whereas the Output Parameter of that task may produce the corresponding ISBN for that book To add an Input Parameter 1 Select the task to add the parameter to We will be setting up Input Parameters for the variables that we created in the Adding Updating Task Variables section previously Go to the Attend University Net and select the Enrol task 2 Right click on the task and choose Update Parameters Mappings An Update Parameter dialog 2 An examination of the XQuery language is beyond the scope of this chapter good XQuery learning resources
71. text input box will appear over the flow Type your desired text and commit the flow label by pressing the ENTER key You may then drag that flow label around to position it as desired 58 CHAPTER 4 THE EDITOR l E My Career _ Attend University Study Private Look for an Easier Book Read a Book Knowledge Feel Smarter Gained Figure 4 16 Adding bends to a Flow Relation Take the two flow relations that have recently had bends added to them Attach the label yes to the flow relation going from the Knowledge Gained condition to the Feel Smarter atomic task Attach the label no to the flow relation going from the Knowledge Gained condition to the Look for an Easier Book atomic task Drag the labels about to a desired position much like what s been done in Figure 4 16 Note that Figure 4 17 shows flows using two different line styles The flow running from Look for an Easier Book has been given the spline line style in this figure while the remaining flows are all orthog onal resulting in sharp edged bends on flows such as the one running from the Knowledge Gained condition to the Look for an Easier Book task Setting Colours For nets the default background colour can be set i e applied to all nets by choosing Default Net Background Colour from the View menu To set the background colour of individual nets choose Net Background Colour from the Net menu
72. the Net Menu We will be setting up Net variables in the Attend University net Go to the Attend University Net and choose Update Net Detail from the Net Menu 2 An Update Net Decomposition dialog box will appear see Figure 4 24 Click on the Create button This will show an Update Net Variable dialog box see Figure 4 25 3 Enter the Name of your variable choose the Type and intended Usage of the variable from those listed then click Done then Done again to close the Net Decomposition dialog ra Enter StudentNumber for the name of the variable leave the type as string and set the Usage type to Local Leave the initial value blank Click Done see Figure 4 25 Create another Net Variable with the name SubjectCode and Type string Leave the Initial Value blank and set the Usage to Local usage types will be explained a little later Click Done 4 The Net Variables should now appear in the Update Net Decomposition of Net Attend University 64 CHAPTER 4 THE EDITOR Update Data Type Definitions lt xei schema xmlns xse http www w3 org 2001 XMLSchema gt lt xs complexType name Geek gt lt KS sequence gt lt xs element name Name type xsistring gt lt xs element name Salary type xs double gt ZES i Sequence gt lt xs complexType gt lt xs complexType name Book gt lt KS tsequence gt lt xs element name Title type xsistring gt
73. the Rule Type list Selecting a task name will display the rules tree for that task in the Tree View This drop down list is disabled for case level rules types Tree View This area displays the currently selected rules tree in a graphical tree structure Selecting a node in the tree will display the details of that node in the Selected Node and Cornerstone Case panels Nodes are colour coded for easier identification Blue nodes represent the root node of the tree Green nodes are true exception nodes i e they are on a true branch from their parent node Red nodes are false else nodes i e they are on a false branch from their parent node Selected Node Displays the details of the node currently selected in the Tree View 162 CHAPTER 7 THE WORKLET SERVICE e Cornerstone Case displays the complete set of case data that in effect caused the creation of the currently selected rule see Adding a new rule below for more details In Figure 7 15 the Cornerstone Case data shows that amongst other things the variable Fever had a value of true while the variables Rash Wound and Fracture each have value of false 7 5 4 Adding a New Rule There are occasions when the worklet returned for a particular case while the correct choice based on the current rule set is an inappropriate choice for the case For example if a patient in a Casualty Treatment case presents with a rash and a heart rate of 190 while the current rule
74. the YAWL system In A Persson and J Stirna editors Proceedings of the 16th International Conference on Advanced Information Systems Engineering CAiSE 04 pages 142 159 Riga Latvia 2004 Springer Verlag W M P van der Aalst B F van Dongen C W Gunther R S Mans A K Alves de Medeiros A Rozinat V Rubin M Song H M W Verbeek and A J M M Weijters ProM 4 0 Comprehensive Support for Real Process Analysis In J Kleijn and A Yakovlev editors Application and Theory of Petri Nets and Other Models of Concurrency ICATPN 2007 volume 4546 of Lecture Notes in Computer Science pages 484 494 Springer 2007 W M P van der Aalst and K M van Hee Workflow Management Models Methods and Systems MIT Press Cambridge MA USA 2002 W M P van der Aalst and A H M ter Hofstede Workflow Patterns On the Expressive Power of Petri net based Workflow Languages In Kurt Jensen editor Proceedings of the Fourth International Workshop on Practical Use of Coloured Petri Nets and the CPN Tools volume 560 of DAIMI pages 1 20 Aarhus Denmark August 2002 University of Aarhus W M P van der Aalst and A H M ter Hofstede YAWL Yet another workflow language Information Systems 30 4 245 275 2005 Michael Adams Facilitating Dynamic Flexibility and Exception Handling for Workflows PhD The sis Queensland University of Technology Brisbane Australia 2007 Available through http www yawl system com Michael Adams Arthur
75. the specification note verification and 4 8 SPECIFICATION ANALYSIS 83 analysis may take some time for large and or complex models and analysis in particular should be unchecked for incremental saves of such models The Create backup checkbox if checked will copy the previous version of the specification file to a file of the same name but with a bak extension Checking this option is recommended Once the dialog is completed click OK to save the file This saved specification file can now be loaded into a running YAWL Engine and executed To import a specification file from a pre 2 0 version of the editor i e a ywl file 1 Click on the Import a YWL Specification file button Fy on the Menu Toolbar or click Specification on the Menu and choose Import from YWL File A window will appear asking you specify the YWL file to import 2 Select the file and choose Open The YWL file will be loaded and converted to a YAWL 2 0 version specification The specification can now be edited and saved as a 2 0 specification in the usual way 4 8 Specification Analysis Verification of specifications for the engine only determines whether the engine will be able to successfully load and begin execution of the specification In contrast the analysis tool can be used to test for deeper issues in the specification The analysis toolbar button B or the matching Analyse Specification menu item under the Specification m
76. these will have only one rule tree in the tree set The other eight tree sets relate to the workitem level seven exception types plus selection and so may have one rule tree for each workitem in the specification that is the tree sets for these eight rule types may consist of a number of rule trees It is not necessary to define rules for all eleven types for each specification You only need to define rules for those types that you want to handle any exception types that arent defined in the rule set file are simply ignored So for example if you are only interested in capturing pre and post constraints at the workitem level then only the ItemPreConstraint and ItemPostConstraint tree sets need to be defined i e rules defined within those tree sets In this example any Timeout exception events that occur during the execution of the specification would be ignored by the Exception Service Of course rules for a Timeout event could be 7 5 WORKLET RULE SETS AND THE RULES EDITOR 157 lt ruleNode gt lt pre gt lt cage gt lt r constraints lt se lection gt lt task name Treat gt lt ruleNode gt lt id gt oO lt id gt lt parent gt 1 lt parent gt lt trueChildt1 lt trueCthild gt lt falsechild gt 1 lt falsechild gt lt condition gt True lt condition gt lt cone lusion gt null lt conclusion gt lt cornerstone gt lt cornerstone gt description gt root level default node lt descripti
77. to those it had when it began execution gt gt Force Complete WorkItem completes a live workitem Execution of the workitem ends and the workitem is marked with a status of ForcedComplete which is regarded as a successful completion rather than a cancellation or failure Execution proceeds to the next workitem on the process path gt Force Fail Workitem fails a live workitem Execution of the workitem ends and the workitem is marked with a status of Failed which is regarded as an unsuccessful completion but not a cancellation execution proceeds to the next workitem on the process path Compensate run a compensatory process i e a worklet Depending on previous primitives the worklet may execute simultaneously to the parent case or execute while the parent is suspended or even removed The primitives Suspend All Cases Continue All Cases and Remove All Cases may be edited so that their action is restricted to ancestor cases only Ancestor cases are those in a hierarchy of worklets back to the parent case that is where a case invokes a worklet which invokes another worklet and so on An example of a definition of an exception handing process in the Rules Editor is below Eo Worklet Rules Editor lt New Conclusion Jota Save Clear Cancel Figure 7 10 Example Handler Process in the Rules Editor When invoked this handler will suspend the current case then run a compensat
78. to the new Multiple Composite Task and from the new Multiple Composite Task to Get a Job 3 You will now need to set the parameters of the Multiple Composite Task in the same manner as those set previously for the Multiple Atomic Task Right click on the task and choose Set Instance Detail Set the Minimum Instances to 5 the Maximum Instances to 100 the Continuation Threshold to 50 and the Instance Creation type to Static 4 Click Done 5 Create a new Net by clicking on the Create a new Net button Ej on the Menu Toolbar or click on Net in the Menu and choose Create Net 6 Give the new Net a name by clicking on the Net Menu and choosing Update Net Detail We are going to call this new Net Study Privately T Return to your original Net and right click on your Multiple Composite Task and choose Unfold to Net You will then be given a drop down list with all the Nets Available choose the Net for this task to initiate and then click Done Choose Study Privately 8 You can now complete your new Study Privately Net represented by your Composite Task Create the following Atomic Tasks in order and then link them with Flow Relations as per Figure 4 13 e Read a Book e Feel Smarter Don t forget to validate your specification 4 3 CREATING YOUR FIRST SPECIFICATION 59 4 3 5 Conditions Conditions represent states of the workflow and can be located in between tasks To create a Condition
79. tripRegistra tionType comprising information of trip start date startDate trip end date endDate whether to book a flight want_flight hotel want_hotel and or car want_car the customer s payment account number payAccNumber and dateType comprising information of year month and day e g both startDate and 5 5 ILLUSTRATIVE EXAMPLES 109 endDate are of date Type 2 Update Data Type Definitions lt Me ischema xmlns xs http wwy ws org 2001L sxNLochena gt esi conplexType name dateType gt x31 Sequence gt lt xs element name year type Ksi integer gt esi element name month type s Es integer gt esi element name day type xsa integer lt MSI Sequence gt lt ex31conplexType gt lt MSicomplexType name tripRhegisterType gt x3 Sequence gt kei elenent name startbate type dateType gt esi e lement name endDate type dateType gt axa element name want flight type xe boolean gt axe element name want hotel type xai boolean gt lt 43 elenent name want car type xei boolean gt aes element name payaccNumber types es string gt lt MSI Sequence gt exo conplexType gt lt Marachema gt Figure 5 14 Updated data type definitions Figure 5 15 shows the net level variable definitions for the process All are local variables of string type except that registrInfo is an output only variable of tri
80. work item will display on a new tab or window depending on browser settings That is when a work item link is clicked e If the work item is on the Offered Available queue it is immediately allocated to you and started then its form is displayed e If the work item is on the Allocated Assigned queue it is immediately started then its form is displayed 6 7 YAWL WORKLIST IGOOGLE GADGET 141 e If the work item is on the Started In Progress queue its form is displayed e If the work item is on the Suspended queue it is immediately unsuspended then its form is displayed Just as it is for the default worklist handler of the Resource Service if the work item was associated with a custom form at design time then the custom form will display if not then a dynamically generated form will appear You do not have to be logged on to YAWL before you click on a work item link in the gadget kas Dp p CJ x e nd u http localhost 8080 resourceService faces dynForm jsp GD F iGoogle X E YAWL 2 0 RSS Form Handler X Work Item successfully processed Please click the button below to close this window tab Done rh Px h Figure 6 22 The Worklist Gadget s Post Form Display Message When you leave the form whether by a Cancel Save or Complete action a message will appear on the page informing of the success or otherwise of the action taken Figure 6 22 Note that your current logon status is unaffected by actions y
81. yawl system com M T Wynn D Edmond W M P van der Aalst and A H M ter Hofstede Achieving a general formal and decidable approach to the OR join in workflow using Reset nets In G Ciardo and P Darondeau editors Proceedings of the 26th International Conference on Application and Theory of Petri nets and Other Models of Concurrency Petri Nets 2005 volume 3536 of Lecture Notes in Computer Science pages 423 443 Miami USA 2005 Springer Verlag
82. 1 1 and modify it so that it looks like this i e the fourth parameter URIEncoding UTF 8 has been added lt Connector port 8080 protocol HTTP 1 1 connectionTimeout 20000 redirectPort 8443 URIEncoding UTF 8 gt 2 5 2 Installing YAWL Services Go to the YAWL Engine download page on SourceForge sourceforge net project showfiles php group_id 114611 amp package_id 124238 and download the file YAWL_2 0_CoreWebServices zip and op tionally the file YAWL_2 0_OptionalWebServices zip Unzip the contents of the file to lt your_tomcat_dir gt webapps directory When Tomcat is re started it will automatically unpack each war file into its own directory under webapps cf Figure 2 13 There are four core web services 1 yawl war the core workflow engine 2 resourceService war handles the allocation of tasks to resources contains the default worklist han dler generates dynamic forms manages codelets manages organisational data 3 workletService war handles dynamic flexibility and exception handling 4 yawlWSInvoker war allocates tasks to synchronous web services The Resource Service is described in detail in Chapter 6 The Worklet Service is described in detail in Chapter 7 The WS Invoker Service is described in Chapter 8 There are three optional web services 1 yawlSMSInvoker war allows tasks to be read and modified via SMS Services 2 digitalSignature war authenticates the information pro
83. 1 What is the YAWL Worklet Service The Worklet Dynamic Process Selection amp Exception Handling Service for YAWL comprises two distinct but complementary services a Selection Service which enables dynamic flexibility for YAWL process instances and an Exception Handling Service which provides facilities to handle both expected and unexpected process 143 144 CHAPTER 7 THE WORKLET SERVICE exceptions i e events and occurrences that may happen during the life of a process instance that are not explicitly modelled within the process at runtime A brief introduction to each Service follows 7 1 2 The Selection Service The Worklet Dynamic Process Selection Service or Selection Service enables flexibility by providing a process designer with the ability to substitute a workitem in a YAWL process at runtime with a dynamically selected worklet a discrete YAWL process that acts as a sub net for the workitem and so handles one specific task in a larger composite process activity The worklet is dynamically selected and invoked and may be created at any time unlike a static sub process that must be defined at the same time as and remains a static part of the main process model An extensible repertoire or catalogue of worklets is maintained by the Service Each time the Service is invoked for a workitem a choice is made from the repertoire based on the contextual data values within the workitem using an extensible set of rules to
84. 15 shows the main screen with the rule set for the Casualty Treatment specification loaded On this screen you may browse through each node of a rule tree set and view the various parts of each node The main features of the screen are explained below oe Worklet Rules Editor lt Browse gt Casualty_Treatment sl L File Rule Options Help alelo Q Blo Rule Type Selection Task Name Tiea Current Task Name a if RDA Tree Cormerstone Case f Rule 0 P Rule 1 J Rues T Ha ari Rule 3 SystolicBP 120 He tou Age a1 ikiii Weight 85 ia Rule 3 Fever true Rash false Wound false Name Buster Legg w Selected Node Node ID 1 Parent Node ID o Conditor Fever true Selected Conclusion 1 select TreatFever Node s Details Description basic worklet for a fever Figure 7 15 Rules Editor Main Screen The Toolbar The toolbar buttons replicate the functions available from the main menu see Figure 7 16 7 0 WORKLET RULE SETS AND THE RULES EDITOR 161 New Tree Close Tree About Box or Rule Set Rules File Viewer Open Rules Add New Config File Rule Node Form Figure 7 16 Toolbar New Tree or Rule Set If there is no rules file currently open in the Editor this button displays the New Rule form to allow the creation of an entirely new rule set file for a specification i e one that does not yet have a rule set file defined If there is a rules file curre
85. 4 Figure 7 32 New Case Launched by the Worklet Service run as completely different cases to the parent process but the Worklet Service keeps track of which worklets are running for which parent cases Go to the Case Mgt page to see that a Casualty Treatment case is still running and that the TreatFever specification has been loaded and it also has a case running Figure 7 33 Go back to the Work Queues page and start the Test Fever workitem The Test Fever workitem has mapped the patient name and id values and the particular symptom fever from the Treat workitem checked out by the Worklet Service In addition it has a Notes field where a medical practitioner can enter observations 176 CHAPTER 7 THE WORKLET SERVICE about the patient s condition Figure 7 34 Enter some information into the Notes field and then complete it Loaded Specifications A simple medical treatment process designed to test and Casualty Treatment i demonstrate the Worklet Dynamic Process Selection Service within the YAWL engine TreatFever Worklet to treat a fever Running Cases 1 Casualty_ Treatment 0 1 2 TreatFever 0 1 Figure 7 33 TreatFever Specification Uploaded and Launched Start the next workitem Treat Fever and then edit it This workitem has two additional fields Treatment and Pharmacy where details about how to treat the condition can be entered Figure 7 35 Enter some data here and then complete it
86. 48 2 mstallatoi edia bee ESE Re eRe WS Bares 7 3 Using the Worklet Selection Service 008 7 4 Using the Worklet Exception Service 008 7 5 Worklet Rule Sets and the Rules Editor 7 6 Walkthrough Using the Worklet Service 7 7 Defining New Functions for Rule Node Conditions 7 8 Sample Log generated by Walkthrough C Other Services 8 1 Web Service Invoker Service 2 ee a 82 OMS SCRVICE 4p ebb be amp We dew a ew ee So TWAT Service 6 4 aa 2 hha dere ee Be ee a es ee ee a 8 4 Digital Signature Services 2 vu aw a aiken SE OER we oO eS 8 5 Email Sender Service 1 0 a Seeking Help CONTENTS Document Control Arthur ter Hofstede version 1 9 September 2008 Consolidation of previous documents conversion to XTX of some of them general cleaning and extensions e g new chapter on engine Arthur ter Hofstede version 1 99 October 2008 First version of chapter on resource perspective Michael Adams version 2 0 July 2009 Major rewrite and addtional sections to align the manual with v2 0 Public release version for YAWL 2 0 Michael Adams version 2 0f September 2009 Updates for several minor Editor enhancements and addition of the Twitter Service amp iGoogle Gadget Feedback Any feedback regarding this manual is very much appreciated If you find there is a topic that is missing or has not been sufficiently well explained
87. 8 shows a simple example worklet to be substituted for the Treat top level task when a patient complains of a fever gt __ _ E Test_Fever Treat_Fever Figure 7 8 The TreatFever Worklet In itself there is nothing special about the TreatFever specification Even though it will be considered by the Worklet Service as a member of the worklet repertoire and may thus be considered a worklet it is a standard YAWL specification and as such may be executed directly by the YAWL engine without any reference to the Worklet Service As mentioned previously those data values that are required to be mapped from the parent task to the worklet need to be defined as net level variables in the worklet specification Figure 7 9 shows the net level variables for the TreatFever task IAO Update Net Decomposition TreatFever Net Decomposition Variables Name Type Usage C Create PatientID string Input only e boolean Input Only _ Update string Input amp Output string Input amp Output ee string Input Only __ Remove Treatment string Input amp Output Figure 7 9 Net level Variables for the TreatFever Specification Note the following e Only a sub set of the variables defined in the parent Treat task see Figure 7 7 are defined here It is only necessary to map from the parent task those variables that contain values to be displayed to
88. AWL however it is easy to configure YAWL for other database back ends see the next section for details Download the latest version of PostgreSQL from www postgresql org download there is a one click installer for each operating system The following is a walkthrough for a Windows installation but it is a similar process for other platforms Except where otherwise mentioned simply accept the default setting for each setup screen For the Service Configuration screen choose the Install as a Service option see Figure 2 14 Leave the account name as postgres and enter any password of at least 6 characters This will be the account the PostgreSQL service uses to run and allow connections to the database j PostereSQL q ioj x all y W Install as a service mema Account password Peete pe The serice account is the account that runs the PostgreSQL database server If pou have not already created an account the installer can do so for you Enter an account name and a password or leave the password Blank to have one auto generated service configuration Service name Account name Account domain Verity password lt Back Cancel Figure 2 14 Choose Install as a Service and enter any password 20 CHAPTER 2 INSTALLATION On the next screen Initialise Database Cluster Figure 2 15 leave all values as they are but enter yawl no quotes all lower case as the password This is the user acco
89. Allocated Queue The Allocated queue lists the work items that have been allocated to a participant Unlike an offer a work item on an allocated queue means that it has been allocated to that participant alone and comes with the understanding that the participant will at some time start the work item and perform its work Work Items Specification Task ListBuilder Create Book List ee 54 Enabled Created Age duli2d 2009 15 23 17 0 00 07 22 Figure 6 13 The Allocated Work Queue A participant may take the following actions on a work item in an allocated queue e Start The work item is started i e begins executing and moved to the participant s started queue e Deallocate This action provides an authorised participant with a means of rejecting a work item that has been allocated to them The work item is removed from the participant s allocated queue the participant is removed from the original distribution set and the work item is redistributed as per the resourcing specification for the task A participant must have the task privilege Can Deallocate to enable deallocation e Delegate This action allows a participant to delegate responsibility for a work item to another par ticipant The receiving participant must be subordinate to the delegating participant by Position The work item is moved from the allocated queue of the delegator to the allocated queue of the receiver 6 4 WORK QUEUES 135 A pa
90. DATA IN YAWL Update Parameters for Atomic Task register Input Parameters a Coes Het Variables Task Variables Mame cus toner i 5 Cus toner registrinto registrinfo flightDetails hotelDetails carbetails Output Parameters Que Met Variable r register customer texti customer JESUS ter telat r tira Figure 5 16 Parameter definition for task register has a boolean value of true or false Note that this flow definition is defined with an OR split so that any number of the flows to booking tasks can be taken Flow detail for Atomic Task register Target Task Predicate book flight Make_Trip_Process regis s i book hotel Make Trip Process regis Predicate book car Make Trip Process regis Y The bottom most flow will be used as the default Done Figure 5 17 Flow definition at task register Figure 5 18 shows the parameter definition of task book flight with four task variables The three input only variables get data from the net via appropriate XQueries Note that both startDate and endDate get data from the net variable registrInfo There is one output only variable called flightDetails which requires the information from the customer such as his her preferable airlines or even an exact flight number The parameter definitions of tasks book hotel and book car are specified in a similar way except that the output only variable is hotelDet
91. For tasks and conditions the default fill colour i e for all newly added tasks and conditions can be set by choosing Default Element Fill Colour from the View menu For individual tasks and conditions right click on it then choose Set Fill Colour from the popup menu Several selected tasks and or conditions can have their fill colour set at the same time by choosing Set Selected Fill Colour from the Elements menu 4 4 2 Editing Objects You can edit more than one object at a time by using the Marquee Selection tool See Figure 4 17 1 Select the Marquee Selection tool E from the Elements panel 2 Click on the first object that you want to edit then hold down the shift key and then click on the other objects that you want to edit 3 Alternately click and drag the Marquee tool to include multiple items in the drag rectangle 4 Now choose the Edit option from the Menu or continue holding down the shift key and right click on the mouse button Below are the edit options e Cut Copy Delete Align 4 4 CHANGING THE APPEARANCE OF YOUR SPECIFICATION 59 f gt My Career LI Attend University O Stud Look for an r Easier Book a a ogee Knowledge Feel Smarter Gained Figure 4 17 Changing the Size of Multiple Objects e Size Increase Decrease to change the appearance of the objects This can also be done using the CTRL key plus Up or Down arrow on your keyboard Note also that when
92. G Name string Output Only Remove YAWL Registered Service Detail YAWL Service Digital Signature Service KA Z Automated Set Codelet Done Cancel MailSender Figure 8 14 Example Mail Sender Process lt option value smtp mail yahoo com gt Yahoo lt option gt lt option value New SMTP gt Name in the dropdown list lt option gt lt select gt The second part of the form is for entering the details of the email In the field Send To enter the email address to send the mail to The Alias will be the name appearing on the receiver s mailbox Then you can add the subject of the mail and the content You can also attach a file if desired The service will then attempt to send the email using the smtp server details provided in the form 208 CHAPTER 8 OTHER SERVICES Figure 8 15 Example Mail Sender Custom Form Chapter 9 Seeking Help Manuals like the software they describe can never be considered to be complete It is quite possible that you run into an issue for which the documentation is lacking or find a problem with the YAWL environment that constitutes a bug Alternately you may discover a new idea on how to enhance the system Here we briefly address the questions of how and where to seek help For queries about the YAWL software we recommend that people use the help and discussion forums at the YAWL sourceforge site http s
93. H M ter Hofstede Wil M P van der Aalst and David Edmond Dynamic Extensible and Context Aware Exception Handling for Workflows In Robert Meersman and Zahir Tari editors On the Move to Meaningful Internet Systems 2007 CoopIS DOA ODBASE GADA and IS OTM Confederated International Conferences CoopIS DOA ODBASE GADA and IS 2007 Vilamoura Portugal November 25 30 2007 Proceedings Part I volume 4803 of Lecture Notes in Computer Science pages 95 112 Springer 2007 Michael Adams Arthur H M ter Hofstede David Edmond and W M P van der Aalst Worklets A service oriented implementation of dynamic flexibility in workflows In R Meersman and Z Tari et al editors Proceedings of the 14th International Conference on Cooperative Information Systems CoopIS 06 volume 4275 of Lecture Notes in Computer Science pages 291 308 Montpellier France November 2006 Springer Verlag M de Leoni W M P van der Aalst and A H M ter Hofstede Visual Support for Work Assignment in Process Aware Information Systems In M Dumas M Reichert and M C Shan editors BPM 2008 volume 5240 of Lecture Notes in Computer Science Springer 2008 211 212 11 12 13 14 15 16 E 17 18 19 20 21 22 23 24 BIBLIOGRAPHY A H M ter Hofstede W M P van der Aalst M Adams and N Russell editors Modern Business Process Automation YAWL and its Support Environment Springer 2010
94. Identifiers panel is where the names of the specification rule type and task name for the new tree are defined The Specification Name input is read only for new rule sets it is the specification chosen via the Specification Location dialog Figure 7 24 for existing rule sets it is the specification for the rule set currently loaded into the Rules Editor The Rule Type drop down list contains all of the available rule types i e all the rule types for which no or incomplete tree sets exist For new rule sets all rule types are available The Task Name drop down list contains all the available tasks for the selected rule type i e tasks for which no tree exists in the tree set for this rule type The Task Name list is disabled for case level rule types e The New Rule Node panel is identical to the panel on the Add New Rule form Here a condition and optional description can be entered and the conclusion for the new rule created or selected from the list depending on the rule type see below e The Cornerstone Case Data panel allows a set of cornerstone data for the new rule to be defined Add a variable name to the Attribute input and give it a value in the Value input then click the Add button to add it to the set of Cornerstone Case data Usual naming rules apply to the data attributes the attribute name must begin with an alpha character or underscore and contain no spaces or special characters e The Effective Composite R
95. PULATE DATA IN YAWL The subnet of task do itinerary segment specifies the simple make trip process that is similar to the one in Section 5 5 2 Thus we do not go into every detail but provide the parameter definitions for tasks register itinerary book flight and prepare pay in Figure 5 27 to Figure 5 29 respectively The parameters for the other two tasks book hotel and book car are defined in a similar way to those of task book flight B Update Parameters for Atomic Task register itinerary Input Parameters XQuery Task Variable do_ itinerary segment customer text customer do_ itinerary segment leg leg Net Variables Task Variables Name Type Usage Name Type Usage customer string Input Output customer string Input Only leg legType Input amp Output leg legType Input Only startDate date Output Only startDate date Output Only endDate date Output Only endDate date Output Only flightDetails string Input Output serviceRequired serviceType Output Only hotelDetails string Input Output carDetails string Input Output subTotal double Input amp Output serviceRequired serviceType Local Output Parameters XQuery Net Variable register itinerary startDate text startDate register itinerary endDate text endDate register itinerary serviceRequired servic
96. Rating Similarly the input only variable rating is defined to convey the credit rating 560 that is only used for client notification upon execution of the task Now we have completed the control flow and the data definition of the credit rating process The specification will pass the syntax check in the YAWL editor and shows that No design time engine validation problems second argument string and otherwise returns false 106 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL Flow detail for Atomic Task ReceivesSn ma pdets bow Prediente __ Target Task Predicate Reporthault starts with Credit_Rati DecideRating true The bottonm most flow will be used as the default F4 Update Task Parameter fault Input Parameters XQuery _ Task Variable _ o of cements coment Credit_Rating_Process fault i kom of not yariehis fout iy A add XQuery of entire element XQuery lt fault gt Credit_Rating Process fault text Net Variables Task Variables Name Type Usage Name Type Usage J ssn string Local 14 fault string Input Only aj rating double Local fault string Local Output Parameters XQuery __NetVariable_ Create f 7 a Y Aj Update lt fault gt Remove populates the task variable foun Figure 5 9 E Update Parameters for Atomic Task DecideRating i Update Task Parameter rating inp Parameters Wue
97. Routing Read a Book Knowledge Feel Smarter gt Plugin Gained a Composite Task Study Privately 82 id Study Privately 82 the XQuery for param null cannot be equal to null or the empty string The task id Study Privately 82 claims to assign its output to a net variable named null However the containing net does not have such a variable Select a number of net elements to manipulate Figure 4 13 Validation with unfinished Multiple Instance Tasks ro E Attend University E Study Privately Begin My Attend Get a Job Career Career University f Started Study Privately Figure 4 14 Making the Study Privately task an atomic composite 4 3 6 Changing the Starting Net At any stage you can change the Starting Net of the specification To change the Starting Net 1 Select Net from the Menu 2 Choose Set Starting Net Figure 4 15 3 From the Choose Starting Net window click on the drop down list and select a new starting Net 4 Click Done Note that the starting net has an input condition symbol gt in its title tab and in the View menu list All sub nets have a composite task symbol o in their title tab and in the View menu list 4 4 CHANGING THE APPEARANCE OF YOUR SPECIFICATION ov 800 Choose Starting Net Execution of the workflow starts in net My Career Study Privately Done I Caritas J Figure 4 15 Changing the Starting Net 4 4 Changing the Appearanc
98. Sequence gt x3r elenent name departure location type xsiatring gt Me element name destination type xs string uaielement name startbate type xs date gt lt xs element name endDate type Ms date ee element name flightDetails type HSi string gt ea element name hotelDetails type xs satring gt xe e lement name carDetails type xs string gt ee e lement name subTotal type xs double gt XSI Sequence gt lt x3 conplexType gt xe complexType name legsType gt lt x gequence gt x5r elenent name Lleg type LlegType mintecurs 1 maxOccurs unbounded gt eS Sequence gt x3 conplexType gt xe complexType name l1egType gt HG Sequence gt x3r elenent name departure location type xsistring gt Me element name destination type xs string gt ESI Sequence gt xs conplexType gt lt xeicomplexTypoe name servicelType gt CXS Sequence gt x3r elenent name want flight type xei boolean gt x3r element name want hotel type xs boolean gt SHS CLEMENT nawe Want car Dype Nei boolean gt ESI Sequence gt lt es conplexType gt lt x ar achema gt LW ERA REAR RRA ARERR RARER RARER REAR REAR AREER REE AREER REE RAGE RA EOE RR EEE ARACEAE OER RA ORR EAGER RAGE RAGA RA GEAR A EAR REAR ROR ER RRA RARER AREER REET REE A AREER REE Figure 5 21 Updated data type definition f
99. SystolicBP 165 Fracture false Fracture false Age 21 Age 66 Weight 65 Weight 107 Fever true Fever false Rash false Rash true Wound false Wound false l Name Buster Legg Name Gammy Ticker Hew Rule Node Mode ID 10 Parent Node ID E Condition Hew Conclusion Description Figure 7 17 Add New Rule Form Clicking on the line HeartRate 190 in the Current Case panel copies that line to the Condition input in the New Rule Node panel Thus a condition for the new rule has been easily created based on the differing data attribute and value that has caused the original worklet selection to be invalid for this case Note that it is not necessary to define the rule as Rash True amp HeartRate 190 as might first be expected since this new rule will be added to the true branch of the TreatRash node By doing so it will only be evaluated if the condition of its parent Rash True first evaluates to True Therefore any rule nodes added to the true branch of a parent become exception rules of the parent In other words this particular tree traversal can be interpreted as if Rash is True then return TreatRash except if HeartRate is also 190 then return where whatever worklet we decide to return for this rule see more below Now the new rule is fine if in future cases a patients heart rate will be exactly 190 but what if it is 191 164 CHAP
100. TER 7 THE WORKLET SERVICE or 189 or 250 Clearly the rule needs to be amended to capture all cases where the heart rate exceeds a certain limit say 175 While selecting data items from the Current Case panel is fast and easy it is often the case that the condition needs to be further modified to correctly define the relevant rule The Condition input allows direct editing of the condition Conditions are expressed as strings of operands and operators of any complexity and sub expressions may be parenthesised The supported operators are shown in Figure 7 18 poe Arithmetic Comparison n lt lt Logical AND Logical OR Logical NOT Figure 7 18 Operators Supported All conditions must finally evaluate to a Boolean value i e true or false TIP In addition to conditions expressed in the above mentioned format conditional expressions may also take the form of XQuery expressions that evaluate to a boolean value To make the condition for the new rule more appropriate the condition HeartRate 190 should be edited to read HeartRate gt 175 After defining a condition for the new rule the name of the worklet to be executed when this condition evaluates to true must be entered in the read only Conclusion field of the New Rule Node panel refer Figure 7 17 To select or create an appropriate worklet click the New button What happens next depends on whether the rule type for the tre
101. The Workflow Elements and Tools panel contains seven selectable buttons five YAWL language icons and two selection tools that assist with creation selection and positioning of objects within your specification This panel is also accessible by right clicking on any blank area of the canvas Once an element is selected it is possible to place objects of that type on the canvas by left clicking the mouse button Atomic Task m Select this button to create an Atomic Task which represents a single task to be performed by a human participant or an external application Composite Task z Select this button to create a Composite Task which is a container for another YAWL sub Net with its own set of YAWL elements constrained by the same syntax Multiple Instance Atomic Task E Select this button to create a Multiple Instance Atomic Task which allows you to run multiple instances of a task concurrently Multiple Instance Composite Tasks a Select this button to create a Multiple Instance Composite Task which allows you to run multiple instances of a composite task concurrently 4 2 THE YAWL EDITOR WORKSPACE 45 Condition Ol Select this button to create a Condition which is a way to represent state for the Net Marquee Selection Eam Lena Select this button to activate the Marquee Selector which will allow you to select individual or multiple objects by clicking and dragging the left mouse button N
102. Tyne sage customer String Input amp Output leg Input Output startDate endDate flightDetails hotelDetails carDetails subTotal serviceRequired Output Parameters Task Variables customer ElightDetails hotelDetails carIetails subTotal Figure 5 29 Parameter definition for task prepare pay 119 Note Since the variable subTotal is of double type the XQuery function number is used to extract data from the variable 120 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL Chapter 6 The Runtime Environment This chapter provides an overview of the runtime environment from a user perspective When a YAWL workflow specification has been completed in the Editor it can be saved to a file the contents of which are in an XML format that can be interpreted by the YAWL Engine The specification file contains descriptions of each of the three perspectives of a process control flow task sequences splits joins etc data variables parameters predicates etc and resourcing participants roles allocators filters etc However the Engine is responsible only for the control flow and data perspectives it essentially ignores the descriptors for resourcing contained in a specification file instead passing responsibility for the resource perspective to a dedicated custom service In the core YAWL environment a custom service called the Resource Service is supplied to provides comprehensive support for
103. WL is to be used within a single user environment So your personal purposes could be to write a workflow research paper based on YAWL or to prepare your next workflow lecture Furthermore YAWL is the right choice if you intend to learn about or to experiment with YAWL The resulting pre configured installation will have full functionality and contains the same YAWL components as YAWL4 Enterprise e YAWL4Enterprise is an installer for Windows only Third party components like Apache Tomcat and PostgreSQL are installed as services so that YAWL can be used as a long running server for production purposes Furthermore the installer allows the configuration of the YAWL environment For production purposes on a Windows platform this is the installer to choose See Section 2 5 for instructions on how to install for multi user production environments on other platforms e YAWLive is a LiveCD which contains a Linux operating system and a fully pre configured YAWL environment No installation is required all that needs to be done is to boot the iso image from a virtual machine or a previously burned YAWLive CDROM This is a great way to use YAWL in an educational setting The complete YAWL environment is installed whatever installer is chosen Further information on the different installer types can be found on the YAWL project web page on SourceForge Installing Maintaining YAWL YAWL Purposes Engine Editor Fits for all purposes except YAWL4St
104. When the Treat Fever workitem is submitted the worklet case is completed The Worklet Service maps the output data from the worklet case to the matching variables of the original Treat workitem then checks that workitem back in effectively completing it and allowing the next workitem in the Casualty Treatment process Discharge to execute Go to the Work Queues page and you ll see that the Discharge workitem is available Figure 7 36 Edit it to see that the data collected by the TreatFever worklet has been mapped back to this workitem Submit it to complete the case B Selection Worklet Enabled Multiple Instance Atomic Task Example This walkthrough takes the List Maker example from the YAWL Editor User Manual and worklet enables the Verify List task to show how multiple instance atomic tasks are handled by the Worklet Selection Service 7 6 WALKTHROUGH USING THE WORKLET SERVICE 177 Edit Work Item 2 1 Figure 7 34 Test Fever Workitem detail Edit Work ltem 2 2 Figure 7 35 Treat Fever Workitem detail The specification is called wLlistMaker The only change made to the original List Maker specification was to associate the Verify List task with the Worklet Service using the YAWL Editor Figure 7 37 shows the specification Go to the Case Mgt page and upload the wlistMaker specification from the worklets folder of the worklet repository Then launch an instance of wListMaker When the case begins enter three valu
105. _Centre 13 02 48 250 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 13 02 48 265 INFO ES Checking post constraints for workitem 21 1 CancelStadium_3 13 02 48 265 INFO ES No post task constraints defined for task CancelStadium 13 10 10 468 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 13 10 10 484 INFO ES Checking pre constraints for workitem 21 Tell_Punters_4 13 10 10 500 INFO ES No pre task constraints defined for task Tell_Punters 13 10 10 500 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 13 10 10 515 INFO ES Checking post constraints for workitem 21 2 Book_Ent_Centre_5 13 10 10 515 INFO ES No post task constraints defined for task Book_Ent_Centre 7 8 SAMPLE LOG GENERATED BY WALKTHROUGH C 195 13 13 59 281 13 13 59 281 13 13 59 281 13 13 59 296 13 13 59 437 13 13 59 468 13 13 59 515 13 13 59 531 13 13 59 531 13 13 59 546 13 13 59 750 13 13 59 875 13 13 59 953 13 14 00 046 13 14 00 046 13 14 00 156 13 14 00 171 INFO E DEBUG Es INFO E DITUC DEBUG ES DEBUG ES INFO ES INFO INFO ES INFO INFO ES DEBUG ES INFO ES INFO INFO INFO ES INFO paraga GL reer corres CE cree TE saramas cores A cree D sere E ree S cree cre 00 ore HANDLE CHECK CASE CONSTRAINT EVENT Checking constraints for end of case 21 No post case constraints defined for spec ChangeToMid Venue Worklet ran as exception handler for case 20 Excepti
106. a Payne Cancel Start Figure 7 29 Launching a Casualty Treatment Case detail Go to the Work Queues page and the first task in the case Admit will be listed as an offered workitem Make a note of the case number Accept amp Start the Admit workitem The Admit workitem simulates an admission to the Casualty department of a hospital where various initial checks are made of the patient You ll see that in addition to the patient name and id specified when the case started there are a number of fields containing some medical data about the patient Each field has some default data to save time but you may edit any fields as you wish Figure 7 30 When done click the Complete button Go back to the Work Queues page and start the next workitem Triage The Triage task simulates that part of the process where a medical practitioner asks a patient to nominate their symptoms You ll see that the patient s name and id have again been displayed for identification purposes in addition to five fields which approximate the medical problem One field should be set to True the others to False Lets assume the patient has a fever Set the Fever field to True the rest to False and then click the Complete button Figure 7 31 There is nothing special about the first two tasks in the process they are standard YAWL tasks and operate as expected However the next task Treat has been associated using the YAWL Editor with the Worklet
107. a ee 4 5 Additional Specification Features aooaa a e e a a AG COn eO aaa e A oh Be EA E ae ee a e RO a eee 4 7 Validating and Saving a Specification s 4404 04 240 4 ea Oe eae RRR AS Speciicadon Anya gx vk eek eed oe Ae ee RR ES eee AY 2kuhOmalCd asks 4 ua oes ew AE Eee eee ORs ee oe tee eee es 4 10 Resource Management Manual task 2 ee Ace Ta kT TNR aa ate ete cer 4G ae Ge Seas eee be Gh ae he eo ee 8 ss ec ee ae a Ps De este CO CO CON N 11 12 12 14 16 16 23 23 24 25 28 36 Ae AD Custom HOrms a 3 amp 4 amp ee ade xk ee hd ee er a st he he ee le i 4 13 Extended Attributes amp 2 4 s ace ee He ee Re Boe ae we S How to Manipulate Data in YAWL Sl Modic Os 62 2 3 sw oh oll Soke eM ec veneer ee ow D2 Pata Visio oa gw a Bw es Boe ar aca a es ew Be eS 539 Data Translebe ga eee kk ee a ow Ee eed ee ee ee ea 5 4 Data related Issues 2 0 0 0 0 ee a 5 5 Illustrative Examples 24 444 wee he a The Runtime Environment 6 1 Resource Service Configuration o o aoa a e a a a 0 00048 O2 beeen Oi gr oa e ek eaa ee eS O25 AAMS 2 2 4 4 5 4 amp amp 2 eike eee ee aro Se we 6 4 Work Queues 245 4 444445 44 646 2 Soe Saweene es 65 User Prones uae eke gee ne See ee Bee eed wt ES 60 Tea Queues sa 2 6 4 6 6 amp ees Be ee ke eo amp 6 7 YAWL Worklist iGoogle Gadget 02 The Worklet Service 7 1 What is a Custom YAWL Service 0
108. a parameters to display or gather values for e Suspend This action suspends the selected work item The work item is removed from the started queue and placed on the participant s suspended queue A participant must have the task privilege Can Suspend to successfully suspend a work item e Reallocate Stateless This action allows a participant to reallocate a work item to another par ticipant The receiving participant must be subordinate to the reallocating participant by Position The work item s data values are reset to the values that existed when the work item was first started i e stateless reallocation and it is moved from the started queue of the reallocator to the started queue of the receiver A participant must have the task privilege Can Reallocate Stateless and have subordinate staff to successfully reallocate a work item e Reallocate Stateful Similar to Reallocate Stateless except that any modified data values are main tained when the work item is reallocated A participant must have the task privilege Can Reallocate Stateful and have subordinate staff to successfully reallocate a work item e New Instance This action allows for the creation of a new instance of the selected work item it is enabled only for a work item of a multiple instance atomic task that allows dynamic creation of additional work item instances e Complete Completes the selected work item The work item is posted back to the
109. ails or carDetails Figure 5 19 shows the parameter definition of task pay with five task variables These are all input only variables and they get data correspondingly from those net variables with the same names 5 5 3 Example 3 Make Trip Process with Multiple Instance Composite Tasks This process provides a booking service for a trip that has several legs For each leg the same simple make trip process in the previous example will be executed As a result we obtain a more complex Make Trip 5 5 ILLUSTRATIVE EXAMPLES 111 A Update Parameters for Atomic Task book flight Input Parameters SAUE Task Variable Make Trip Process customer text customer ieee Trip PPE say Ge Oe ee neritic 1 Make Trip Process regiatrinto endDate Het Variables Task Variables Mame Customer Customer registrint o tripRegisterType Output Only SstartDate Input Only ElightDetails endDate Input Only hotelDetails ElightDetails string Output Only carbetails Output Parameters B Update Parameters for Atomic Task pay Input Parameters SAUE Task Variable fMake Trip Process customer textt customer Net Variables Task Variables Mame customer customer j Input Only regiatrInfoa tripRegqisterType Output Only flightDetails string Input Only flightDetails string bocal hotelbetails Input Only hotelDetails carbetails Input Only carbetails payAccNumber Input Only Output Parameters het Variable
110. al data transfers 3XQuery 1 0 An XML Query Language W3C Working Draft 4 April 2005 102 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL Input and output variables combine usages No internal data transfers are allowed to local variables of subnets and no external data transfers are allowed between local variables and the external environment Note In Chapter 4 Section 4 5 7 illustrates how to pass data between variables in the YAWL Editor Three things are worth noting 1 The YAWL Editor enforces correct data transfers between variables in the parameter definition for each task For example it is not possible to define data passing between local variables or to set more than one input output parameter on a single variable associated with a task 2 Inthe YAWL editor by running specification validation a user can check whether or not required data transfers are missing For example if an input variable V in of a task T does not have any data mapping specified the validation result will indicate that there exists an input parameter V in in task T that is not mapped to by this task 3 When specifying XQueries in the parameter definitions of a task the YAWL editor may automatically generate an engine compatible XQuery or indicate whether a user defined XQuery has valid or invalid syntax by displaying the query in green or red respectively The semantics validation of XQueries is performed at run time by the YAWL en
111. ameter mapping is required This task will show the user the results of any data changes done during the execution of the MI task thus its variable is input only meaning that the values are display only e Add a decomposition to the MI task and call it Verify List To the decomposition add a variable called book of type BookOrder and usage Input amp Output Note carefully that the task variable we have added to the decomposition is of BookOrder type in our data definition we have defined the BookList type being comprised of a number of BookOrder type elements so what has been defined in this decomposition is a mapping of a single BookOrder to each task instance that will be created when the MI task is executed e The mapping of input and output parameters for MI tasks is done a little differently to atomic single instance tasks and involves a two stage process Open the Update Parameter Mapping dialog for the MI task Verify List and add the input and output parameter mappings as seen in Figure 4 36 Notice that the input parameter maps the entire net level variable MasterList to book a single task level BookOrder variable while the output parameter maps the contents of the book variable wrapped in order tags back to the net level MasterList These kinds of mappings would be invalid for a single instance task but here we need to define a mapping that on input takes a net level list a
112. ameter which at runtime will contain a participant s userid or the name of a role Participants Roles Net Parameters Kay Adams ka Account Manager r Refers to Peter Clemenza pc T Carrier Admin Officer resource Role Don eone dvc HT Client Liaison Fredo Corleone fc Courier Michael Corleone mec Finance imoer Sonny Corleone sc ment Manager Don Carmine Cuneo dec PO Manager Tom Hagen th Senior Finance Officer Captain McCluskey cme H senior Supply Officer Carle Bitzi irri Shinment Planner Unselect All Unselect All lt Back gt Next Finish Figure 4 50 Step 2 of the resource management wizard e do not allow the work items of the selected task to be offered to participants who are members of the set specified in Step 2 and have previously completed work items of another task as specified in the current process instance e Allow all of the work items of the selected task to be piled to a particular participant which means that if a participant chooses to pile a work item of the task that participant will be automatically allocated the work item and all future instances of work items of the task for all future instances of the process containing the task until such time as piling is turned off for that task by the participant or an administrator Step 4 In Step 4 shown in Figure 4 52 we can select the allocation mechanism that determines at runtime which participant chose
113. amp Height double Input HeartRate long Input Pharmacy string Input amp systolicBrP long Input Fracture boolean Input Age long Input Treatment string Input amp Weight double Input Fever boolean Input Rash boolean Input Wound boolean Input AbdominalPain boolean Input string Only Default Engine Worklist Web Service Invoker Service Automated Remove Set Codelet B Figure 7 7 Associating a task with the Worklet Service 7 3 2 Worklet Specifications When the Casualty Treatment top level specification is executed the YAWL Engine will notify the Worklet Service when the worklet enabled Treat task becomes enabled The Worklet Service will then examine the data in the task and use it to determine which worklet to execute as a substitute for the task Any or all of the data in the task may also be mapped to the selected worklet case as input data Once the worklet instance has completed any or all of the available output data of the worklet case may be mapped back to the Treat task to become its output data and the top level process will continue A worklet specification is a standard YAWL process specification and as such is created in the YAWL Editor in the usual manner Each of the data variables that are required to be passed from the parent task to the 7 3 USING THE WORKLET SELECTION SERVICE 151 worklet specification need to be defined as net level variables in the worklet specification Figure 7
114. an simply try and check all reachable states but this is obviously not possible when this state space is very large or infinite In those cases we can check whether it is possible to reach the final state from the initial state Hence does a scenario exist where we reach the final state The richer concepts offered by YAWL also introduce additional correctness notions For example an analyst may have used an OR join where an XOR join or an AND join could have been used This is not desirable for computational reasons but also because it makes the process model harder to understand Hence the YAWL environment will check whether all OR joins are immutable Another correctness notion is that of irreducible cancellation regions Here it is checked whether certain conditions or tasks can be removed from a cancellation region as they will never contain a token or will never be active when the associated cancellation task executes The YAWL editor offers two different approaches to automated verification One approach 23 is based on the theory of Reset nets this is built into the Editor The other approach 21 uses Petri net theory and in particular the concept of transition invariants For this latter approach the program wofYAWL is to be used the executable of this program should be put in the same directory as the Editor under the name wofyawl0 4 exe These approaches are different in that there are workflow specifications where one of them ca
115. ants For example bank teller police constable credit officer auditor properties manager and junior programmer are all examples of roles that may be carried out by one or more participants within an organisation There may be several participants performing the same role for example a bank may have a number of tellers so a typical role in an organisational model may contain a number of participants Conversely a certain participant may perform multiple roles Further a role may belong to a larger more general role for example the roles junior teller and senior teller may both belong to a more general role called teller A role may be included in the distribution set for a task at design time meaning that all of the participants performing that role or any of its sub roles are to be considered as potential recipients of a work item created from the task at runtime 6 3 ADMINISTRATION 127 a Work Queues Edit Profile Team Queues Admin Queues Cases Users Org Data Services Logout ap Roles Capabilities Positions OrgGroups Role Names Description Belongs To nil Save New Shinment Planner Reset Remove Figure 6 5 Organisational Data Management Capability A capability is some desired skill or ability that a participant may possess For example first aid skills health and safety training a forklift license or a second language may all be considered as capabilities that a parti
116. any problem in the Engine Now we will introduce some errors into the above specification to see what we will encounter via design time or run time validation These errors are considered to be common when designing especially large YAWL specifications Error 1 Missing Data Assignment for Input Variable Assume that we forget to specify the mapping from net variable fault to task variable fault in the input parameter definition for task ReportFault see Figure 5 11 This results in two syntax errors after validation of the CreatRatingProcess specification in the Editor as shown in Figure 5 11 YAWLEditor PSF HomeWatal YAWL 2 0 Examples CreditRatingProcess ywl Specification Net Edit Elements Tools View Help Beh wv yb P 4 Task Icon No Icon ReceiveSSN 6 Manual a Automated b ReportFault gt g Routing J Plugin Y Notes Specification Validation Problems Atomic Task ReportFault 4 id ReportFault 4 the XQuery for param fault cannot be equal to null or the empty string The task id ReportFault 4 needs to be connected with the input parameter fault of decomposition YAULServiceGateway ReportFault Use the palette toolbar to edit the selected net Figure 5 11 An invalid specification with missing data supply for an input variable Error 2 XQuery with Invalid Semantics Assume that we use XQuery ReceiveSSN ss
117. any results to the chosen output variables of the task Both task types are handled by the Resource Service but the behaviour of an automated task differs as follows e on enablement it is automatically checked out of the engine thus having priority over manual tasks in a deferred choice and its input parameters are parsed e if a codelet has been specified it will be executed it using the task s variables as required then e it is automatically checked in and its output variables are mapped back to the corresponding net variables A task is designated as manual by default but can be set as automated by right clicking on it and selecting the Task Decomposition Detail dialog then ticking the Automated checkbox in the External Interaction section see Figure 4 29 When the Automated checkbox is checked the option Manage Resourcing in the task s right click menu will be disabled since human resources are not required for automated tasks Data manipulation can be achieved by using the task s variables and their Input and Output Parameters Parameters are generally used to copy the content of a net variable to a task variable and back again But parameters may also contain an XQuery expression that uses static values or the values of other variables to copy data between net variables and task variables Figure 4 47 shows an simple example of copying from expression where the literal true is copied onto the net variable PO_timedout
118. any years ago workflow was a bit of a dark art practised by deep pocketed companies that were able to afford expensive workflow management systems and highly specialised consultants Today workflow technology is widely available and its benefits and pitfalls are more widely understood A word of warning though while workflow doesn t have to belong to arcane masters of lore it s also not something to trivialise If a workflow application is not aligned with the business it s been deployed in it can be worse than a manual paper based bureaucracy It is therefore important that both business and IT stakeholders follow a sound BPM methodology before attempting to deploy a workflow application But assuming you ve decided on a workflow solution it s time to make a choice You can still choose to pay for a workflow system or you can get one for free If you re for the latter maybe YAWL is for you YAWL which stands for Yet Another Workflow Language is a fully open sourced workflow system or business process The term business process management system BPMS is often used to refer to something similar to a workflow management system The difference is that a BPMS supposedly offers richer functionality for analysing business processes while workflow systems traditionally focused on the co ordination of tasks However the gap between these two is narrowing and it is difficult to differentiate modern workflow management systems and BPMSs
119. ask B e g variable Vb an appropriate net variable of N e g Vn must be available to convey data from Va to Vb In the YAWL editor each task can be assigned an input parameter and or an output parameter depending on the specified Usage type which define internal data transfer associated with that task Input Parameters use an XQuery to extract the required information from a net variable and pass such information to the corresponding task variable while output parameters define data passing in the opposite direction Considering the process depicted in Figure 5 1 Figure 5 3 shows an example of passing the customer information from the net level to the task level task Decide lt custN ame gt M Twein lt custN ame gt lt PerformBooking gt lt departure gt 2005 12 07 lt departure gt Custlnfo lt requireCar gt lt requireF light gt lt Decide gt lt Custinfo gt lt CustName gt M Twain lt CustName gt lt TargetStartD ate gt 2005 12 07 lt T ar lt Custinfo gt lt wantC ar gt lt wantF light gt lt wantHotel gt lt Decide gt lt totalPrice gt _ lt PerformBooking gt WantF light VWantHotel i Decide Figure 5 3 An example of data transfer from net PerformBooking to task Decide External data transfer does not apply to any local variable or any variable of a composite task This is because the local variables cannot be ob
120. at parameter at run time A task parameter with an output designation can have its data output to a containing net level parameter once a task instance has completed Just like task parameters net parameters may have input and or output designations But in addition to these two options net parameters may have a local designation You can think of a net parameter with a local designation as a local variable They are used to store intermediate data during the execution of a process instance Data transfer from a net a task is achieved via inbound mappings An inbound mapping is a statement that says how to transfer data from the net s parameters to a task s input parameters Inbound mappings are evaluated when the task starts Conversely once the task is completed data is moved from the task s scope to the net scope by means of outbound mappings An outbound mapping is a statement that says how to move data from the task s output parameters to its containing net s parameters XPath expressions are For more advanced workflows XPath expressions may prove too limiting Accordingly YAWL allows developers to also use 32 CHAPTER 3 GETTING STARTED WITH YAWL 90609 Manage Resourcing Wizard for Atomic Task Receive and Validate Application Step 1 Choose Behaviour At Interaction Points There are three key decision points for managing the resourcing of work items spawned from a task At each of these interaction points you m
121. at task can be allocated to amongst other things discussed in later sections This menu item allows you to set the parameters for a connection to the Resource Service and to proceed with a connection e Configure Specification Analysis This item will display a dialog where various verification and analysis techniques may be chosen If the wofyawl analysis utility is also supplied in the same directory as the editor the configuration dialog will allow specification designers to configure and use wofyawl for additional specification analysis 1Only available when installed in a Windows environment 44 CHAPTER 4 THE EDITOR View You can use this menu to toggle e Tooltips which provide useful hints when your mouse is positioned over various items e Anti aliasing of graphical components and e Grid on the canvas background useful for aligning objects visually This menu also provides options to set the font size used for element labels the default background colour for nets and the default background colour for elements i e tasks and conditions Finally it shows a list of all the nets of the loaded specification allowing the selection of one from those available for editing Help The Help Menu provides an About the Editor dialog describing components used in the editor s construc tion a list of source code contributors and the version and build date of the Editor in use 4 2 3 Workflow Elements and Tools
122. ata transfer dialog All of the available net level variables for the task s containing net will be listed in the dialog Simply check the boxes for the desired inputs and outputs This dialog will automatically create a task decomposition and matching XQueries to directly transfer data from a selected net variable to a task variable of the same name and back again 4 5 11 End of Scenario This is where our scenario ends The My Career Scenario was designed to outline the basic the functions of the YAWL Editor and to provide you with a understanding of designing a YAWL workflow specification But the functionality of the YAWL Editor does not stop here If you are after something more challenging try adjusting your version of the scenario to expand into more sub Nets and more complex situations 4 6 Connections 4 6 1 Connecting to the YAWL Engine Each atomic task in a YAWL specification must be associated with a service that will be responsible for performing the work of the task If you do not explicitly specify a service for a task by default the task will be assigned to the Resource Service to be displayed in its worklist handler If you want to associate a task with a service other than the Resource Service you can make the appropriate choice from a list in the task s decomposition dialog see the following section The Editor populates the list of available services by 4 6 CONNECTIONS 19 making a call to a running Eng
123. ated Decomposition Name Description This codelet is a simple example of codelet construction and usage It adds two integers Required parameters Inputs a b both Long types Output c also a long this codelet executes an external program Required parameters Inputs command type String required ExampleCodelet ShellExecution env attrib value pairs optional dir type String optional Dutput result type String This codelet executes an XQuery Required parameters Input query type String required the XQuery plus other values used by the XQuery Output result type String XQueryEvaluator OK Cancel Figure 4 48 The Set Codelet dialog 4 10 Resource Management Manual task Once a connection with the Resource Service has been established any manual atomic task with a decom position a task is manual by default and only becomes automated when explicitly checked as automated in the Task Decomposition Dialog can be allocated resources via a number of steps by right clicking on the task and selecting Manage Resourcing This will launch the resource manager wizard Figure 4 49 shows the dialog window for Step 1 of the wizard Step 1 In Step 1 we can specify the interaction strategy for work items of the selected task There are three interaction points offer allocation and start each of which may be either User or System processed If we choose that work items are to be Offered
124. atures of the New Rule form for adding a new rule set and 168 CHAPTER 7 THE WORKLET SERVICE describe how the process differs for existing rule sets as necessary rd To create a new rule set click the Fle menu then select New or click the New Rule toolbar button To add a new rule set make sure there is no rule set file currently open in the Editor If you are creating a new rule set a dialog will display asking for the path and file name of the specification for which the rule set is being created Figure 7 24 pt Specification Location Please select or enter the path to the specification file that the new tule set will describe specication File C Worklets repository worklets TreatF ever xml UE Cancel Figure 7 24 oo Worklet Rules Editor Create New Rule Set Process Identifiers Specification Name IT reatFever Rule Type Task Mame EP New True Rule Figure 7 25 The Specification Location Dialog Hew Rule Node Node ID li Parent Node ID fo Condition Conclusion Description Comerstone Case Data Attribute Value Add gt Effective Composite Aule Add Aule Cancel The Create New Rule Set Screen Figure 7 25 shows the Create New Rule Set form The form allows you create a rule set one rule tree at a 7 0 WORKLET RULE SETS AND THE RULES EDITOR 169 time for the selected specification rule type and task name On this form e The Process
125. ault SE Done A a _ _ _ _ _ Figure 4 33 Updating Flow Detail 4 5 9 Multiple Instance Queries Now that we have an understanding of parameter setting and XQueries we can revisit from a data perspec tive parameter setting for the particular requirements of Multiple Instance MI Tasks In general terms an MI task receives as input from a net level variable mapping a variable of complex type typically a list of some other data type but more complex constructions are of course supported too which it then splits into a number of logically distinct data values to form the data that is assigned to each task instance When the MI task completes it gathers all the individual pieces of data from the various task instances and reconstructs the complex type variable so that it can be mapped back to the net level variable To illustrate the operation of MI tasks with particular emphasis on the data perspective we will use the List Builder specification shown in Figure 4 34 which begins by compiling an order a list of book titles It then creates a number of MI task instances one for each book title in the list of books Once all the MI task instances complete the updated list is recomposed and shown in the final task Create Book Verify List Show List List Figure 4 34 Example specification with a Multiple Instance Task To prepare this specification drag two atomic tasks and one MI task
126. ay choose to have the system dynamically make a decision on resourcing at each point or alternately allow a user to manually make each decision Each interaction point is briefly described below Offer The point at which it is decided that a number of participants could undertake the work item Allocation The point at which one of the participants offered the work item is nominated to do that work item Start The point at which the participant allocated a work item begins working on it Offering a work item for this task to a number of participants is to be done by User System Allocating a work item for this task to one of the offered participants is tobe done by User C System Starting an allocated work item of this task is to be done by User System lt Back gt Next Finish Figure 3 7 Specifying the Interaction Strategy OO0O Manage Resourcing Wizard tor Atomic Task Determine Credit Requirements Step 2 Specify System Behaviour when Offering a Work Item The offer process involves choosing which participants should be informed of the existence of the work item one of whom will eventually do this work As you have specified the system manage the offer process you must now choose who the work item should be offered to Begin by specifying a set of participants and or to distribute offers of work to You may also specify a net parameter which at runtime will contain a participant s userid or t
127. ays be derived from design time resourcing parameter settings in any case By setting this parameter to false no offer events will be logged logging of all other events will still occur e DropTaskPilingOnLogoff A participant who has been granted the authority to pile a certain task may then explicitly and manually choose to do so which means they will receive all instances of that task across all current and future instances of the process that contains the task When this parameter is set to true piling of tasks for a participant will cease when the affected participant logs out When this parameter is set to false the default piling of tasks for a participant will continue whether the participant is logged on or not until it is explicitly ceased by the affected user or an administrator This setting is ignored i e treated as true if persistence is not enabled This parameter applies globally to all piled task participants e GenerateRandomOrgData This parameter allows you to quickly fill the organisational data base with randomly generated data participants roles positions capabilities and org groups which is 6 2 LOGGING ON 123 especially useful for testing purposes or to examine the capabilities of YAWL without first having to manually populate the org database with real or dummy data A parameter value of between 1 and 100 will generate that number of randomised participants with associated membe
128. be of some benefit to long running instances Figure 6 3 Admin Queue Tool Buttons Synch left Refresh right 126 CHAPTER 6 THE RUNTIME ENVIRONMENT 6 3 3 Service Management am Work Queues Edit Profile Admin Queues Cases Users Org Data Logout p Registered Services Name Service URI Description DigitalSignature http Aocalhost 8080 DigitalSignature ib Digital Signature Service http localhost 8080 yawlWSInvoker WS Invoker Figure 6 4 Service Management The Service Management Screen can be used to add to to remove registered services In the screen shot of Figure 6 4 two services are already registered the Digital Signature Service and the Web Service Invoker Service A new service can be added by providing a Name a URI and a Description While the URI is validated by contacting it and waiting for an appropriate response care should be taken that the URI provided exactly matches that of the specified service By using the Editor when connected to the Resource Service see Section 4 6 2 such services can then be assigned to tasks see Section 4 6 3 To deregister a service from the Engine select it in the list then click the Remove button 6 3 4 Managing Organisational Data Roles capabilities positions and organisational groupings can be defined through the Org Data Met Screen see Figure 6 5 e Role Generally a role is a duty or set of duties that are performed by one or more particip
129. ble defined so that the YAWL worklist s view edit button will not be available and you will not be able to access the Custom form menu Second define the Custom form for the task by right clicking on the task and selection Set Custom Form from the menu The address of the custom form is http localhost 8080 mailSender WebMail jsp remember to replace localhost with the specific hostname when the service is not installed locally When invoked at runtime the custom form will look like the example in Figure 8 15 You can see that the form in Figure 8 15 contains two parts The first is to set the SMTP parameters to send email 1 You need to chose in the dropdown list which SMTP you would like to use to send emails 2 You also need to enter login and password to connect to the SMTP server To add another SMTP server you have to edit WebMail jsp and add an option value pair to the dropdown list of servers lt select name SMTP onChange messageValue gt lt option value smtp qut edu au gt QUT WebMail lt option gt lt option value smtp gmail com gt Gmail lt option gt 8 5 EMAIL SENDER SERVICE 207 868 O9 Update Task Decomposition Verify Signature Extended Attributes Task Decomposition Label Verify Signature Task Decomposition Variables Name Type Usage Create a Signature string Input Only Update CheckSignature string Output Only il Document anyType Output Only
130. ccNumber Met Variable Create Update Remove Figure 5 24 Parameter definition for task pay 115 endDate and serviceRequired are input amp output variables conveying data between root net and the subnet The variable serviceRequired contains information only used within the subnet and is therefore defined as a local variable The startDate and endDate variables are output variables reporting the user input back to the corresponding net variables Also the input parameter definition for variable leg and the output parameter definition for variable itinerary are both determined by the task instance queries see below 116 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL A Update Parameters for Multiple Composite Task do itinerary segment Input Parameters AOUE Task Variable make trip customer texti customer make trip flightDetails textl FlightDetails make trip shotelDetails textt i hotelDetails fA Create i nake trip carDetails texti j number fmake trip subTotal text jude trip Legs Update Remove Net Variables Task Variables Mame Type Usage Mame Type sage customer string Local gt customer string Input Output itinerary leg legs startDate startDate endDate endDate flightbetails flightDetails Local hotelDetails hotelDetails carDetails carDetails subTotal payAccNumber serviceRequired serviceType Local subTotal x Output Parameters AALE Met Va
131. cept the terms of this agreement before continuing with the installation GNU LESSER GENERAL PUBLIC LICENSE Version 2 1 February 1999 Copyright C 1991 1999 Free Software Foundation Inc 51 Franklin Street Fifth Floor Boston MA 02110 1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed This is the first released version of the Lesser GPL It also counts as the successor of the GNU Library Public License version 2 hence 4 A N l accept the agreement Do you accept this license e do not accept the agreement Back E cancel Figure 2 2 License Agreement The next step is to select the installation directory figure 2 3 The default location is your home directory The installer will inform you if you re allowed to install YAWL in the selected folder In case of Windows or Linux folders like C Program Files or usr local are only writeable by users with administrative rights Install YAWL into your home directory if you don t have administrative rights YAWL directory v Please specify the directory where the YAWL environment will be installed home sclemens YAWL4Study 2 0 betal S Figure 2 3 Select Installation Directory After clicking Nezt the installer will look for a valid Java installation The dialogue box in figure 2 4 will only appear if Java has been detected on your system P
132. cessmining org This link is for example exploited in 15 to provide simulation support for YAWL There exists support for exporting YAWL logs to ProM which can subsequently be analysed by one of the many mining plug ins available in this environment Alternative ways of presenting work lists have been addressed in 10 In this framework users can choose a map not just a geographical map but also e g a timeline or a YAWL specification and work items can be positioned on this map and be shown in a colour that reflects their level of urgency a context specific notion which can be defined for the user It is expected that this work becomes part of the YAWL distribution in the near future Finally a textbook on YAWL called Modern Business Process Automation YAWL and its Support Envi ronment is to be published by Springer in October 2009 10 CHAPTER 1 INTRODUCTION Chapter 2 Installation The YAWL System comprises a number of web services and a java based Editor It requires a Servlet Container to host the web services and a back end database system for process data storage and archiving Individual YAWL components may be installed manually see Section 2 5 but there are also a number of automatic YAWL installation packages that install all the required components and allow you to be up and running with YAWL quickly and easily e YAWLAStudy is available for Windows Linux and Mac OSX platforms This is the installer to choose if YA
133. ch flows should be activated at runtime This is achieved by associating a boolean XQuery expression with each flow At runtime the flow expressions are evaluated and e if the split type is an OR split each flow that has an expression that evaluates to true will be executed 12 CHAPTER 4 THE EDITOR 60 NO9 Update Parameters for Atomic Task Enrol Input Parameters XQuery Task Variable Create Attend University StudentNumber text StudentNumber Attend_University SubjectCode text SubjectCode T Update Remove Task Variables Name Type Usage string Input amp Output SubjectCcode string Input amp Output SubjectCode string Output Parameters XQuery Net Variable Create Enrol StudentNumber text StudentNumber o Enrol SubjectCode text Subjectcode Update a Remove Done Figure 4 32 Established task parameters e if the split type is an XOR split the first listed flow that has an expression that evaluates to true will be executed Since it is possible that all flow expressions evaluate to false XOR and OR splits must nominate a default flow which will activate if all of the other flow expressions evaluate to false to ensure that the workflow does not deadlock i e is not blocked at that point from proceeding and eventually completing Default flows are defined by prioritising the order in which the various flows of a split are evaluated the on
134. cipant may possess that may be useful to an organisation There may be several participants within an organisation possessing the same capability and a certain participant may possess a number of capabilities A capability or capabilities may be included in a filter defined at design time that is run over the distribution set for a task at runtime so that only those participants within the distribution set that possess the specified capability or capabilities are potential recipients of a work item created from the task Position A position typically refers to a unique job within an organisation for the purposes of defining lines of reporting within the organisational model Examples might include CEO or Bank Manager or may be internal job codes such as TEL0123 A position may report to zero or one other positions for example bank teller TEL0123 may report to the Bank Manager and may belong to zero or one Org Groups see below Like capabilities a position or positions may be included in a filter defined at design time that is run over the distribution set for a task at runtime Positions are also used at runtime to enable resource patterns such as delegation reallocation and viewing of team work queues see Section 6 4 for more details Org Group An organisational group org group is a functional grouping of positions Common examples might include Marketing Sales Human Resources and so on but may be any grouping r
135. ction Screen To raise an unexpected exception at the case level follow a similar process at the Case Mgt screen but instead click the Raise Exception button On the Raise Case Level Exception screen discussed in Walkthrough D select New External Exception from the list and submit the form You will be redirected to the Define New Case Level Exception screen Enter a proposed title a description of the scenario what has happened to cause the exception and a optionally a proposal or description of how the new worklet will handle the exception in plain text and then submit the form See Figure 7 55 for an example using the Organise Concert specification Raising an item level exception is identical except that the Raise Exception button is clicked on the Work Queue screen rather than the Case Mgt screen The information entered on the form is sent to a Worklet Service Administrator who will action the rejection 190 CHAPTER 7 THE WORKLET SERVICE or new exception by adding a new rule to the rule set and optionally having the Rules Editor notify the service to reselect the new worklet using the updated rule set see Section 7 5 2 on the Rules Editor for more detail The process requires a user with administrator privileges to action the rejection request rather than allow all users access to update rule sets Note Rejecting a worklet selection or raising a new unexpected exception will automatically suspend the paren
136. d and a scope defining the visibility of the parameter 3 4 ADVANCED WORKFLOW CONCEPTS 31 e080 YAWL 2 0 User Maintenance SP FC M B oF Be W http locathost 8080 resourceService faces participantData jsp amp y eni Google ez amp ae re r aaa pae a Le zi FirstName mimaa S S M Choose Which Work Item to Start LastName Corieone Start Work Items Concurrently User ID me C Administrator W Reorder Work Items C View All Work Items of Team C View All Work items of Org Group C Chain Work Item Execution C Manage Cases Senior Credit Officer Account Manager PO Manager Carrier Admin Officer Figure 3 6 Defining a Participant Parameters can belong to one of two scopes which we ll name net scope and task scope At runtime every net and task instance with a decomposition will have data stored as a number of parameters belonging to it To get data from a net instance to a task instance it contains or visa versa we require a data transfer In YAWL all data is passed this way from net level to task level when a task instance starts and from task level back to net level when the task instance completes data cannot be directly transferred from one task instance to another Valid designations for a task parameter are input output or both Input amp Output A task parameter with an input designation is one where we expect data to be delivered from a net level parameter to th
137. d capabilities and whether he she has administrator privileges All of this information is read only 138 CHAPTER 6 THE RUNTIME ENVIRONMENT e A Change Password panel where the participant may change their password Passwords must be at least 4 characters in length and the New and Confirm entries must match e A Piled Tasks panel where all of the tasks that are currently piled to the participant are listed The participant may choose to cease the piling of a task to them by selecting it from the list and clicking the Unpile button e A Chained Cases panel where all of the cases currently chained to the participant are listed The participant may choose to cease the chaining of a case to them by selecting it from the list and clicking the Unchain button 6 6 Team Queues Work Items Specification Task amp 51 Create_Book_List_4 ListBuilder Create Book List Case Status Team 51 Enabled f3 OrgGroup Created Age Jul 23 2009 13 27 13 0 00 06 53 Assigned To 1 Resource State H Van Arsdale Billy F Offered Figure 6 18 The Team Queues Screen The Team Queues screen shows groups of active work items in a single list There are two types of groupings possible e A participant who has been granted the user privilege View All Work Items of Team may view a list of all the active work items that appear on the work queues of all the participants who are subordinate to them by P
138. d clicking the Cancel Case button 6 3 2 Admin Queues An administrator can view all of the various work items that are currently active and their status in the Admin Queues Screen see Figure 6 2 There are two Admin queues each of which can be selected by clicking on the appropriate tab Worklisted which lists all the work items on participants work queues and Unoffered which lists the active work items that do not currently reside on any participant s queues From the Unoffered queue an administrator can assign unoffered work items to the offered allocated or started work lists of selected participant s via the buttons Offer Allocate and Start respectively From the Worklisted queue an administrator can change the participant and or the status of the work item through the Reoffer Reallocate and Restart buttons Reverting to a previous state is allowed using these 6 3 ADMINISTRATION 125 Work Items Specification Task 3 Emergency Assess affected area m Case Status Created Age Directly to me Jul 21 2009 18 43 10 0 21 53 05 Figure 6 2 Administration Queues buttons e If the current resource status is Offered the work item may be Reoffered to one or more participants e If the current resource status is Allocated the work item may be Reoffered to one or more participants or Reallocated to a single participant e If the current resource status is Started the work item may be Reoffered to one o
139. date your specification Validation should fail and report errors as per Figure 4 13 The problem here is that the Study Privately multiple instance composite task needs to have more information specified for it to be valid For setting data detail of multiple instance tasks please see Section 4 5 9 7 Remove the Study Privately multiple instance composite task and replace it with an atomic composite task using the same decomposition and re drawing flows from Begin My Career and to Get A Job tasks Your updated net should look like Figure 4 14 and should validate successfully The Knowledge Gained condition in Figure 4 13 shows an example of a Deferred Choice construct When the condition is reached during execution of the process both of its outgoing flows are activated note that a condition may have any number of outgoing flows This results in both the Look for an Easier Book and Feel Smarter tasks appearing in the user s worklist allowing the user to make a deferred choice between the two As soon as the user chooses the appropriate task for execution the other task is immediately withdrawn and is removed from the worklist CHAPTER 4 THE EDITOR YAWLEditor Users adamsmj Documents research temp myCareer yawl E O Q My Career Attend University I Study Privately Og ts Look for an 2 Task Icon Easier Book No Icon gt Manual gt T Automated e i
140. db2 jdbc app DB2Driver url jdbc db2 test username db2 password db2 hibernate connection driver_class org gjt mm mysql Driver hibernate hibernate hibernate hibernate Oracle hibernate hibernate hibernate hibernate hibernate connection connection connection connection connection connection connection connection dialect org hibernate dialect MySQLDialect hibernate driver_class com mysql jdbc Driver url jdbc mysql yawl username root password dialect org hibernate dialect Oracle9Dialect dialect org hibernate dialect QOracleDialect hibernate driver_class oracle jdbc driver OracleDriver username ora password ora url jdbc oracle thin localhost 1521 test Listing 2 1 hibernate properties file excerpt Chapter 3 Getting Started with YAWL 3 1 Introduction Nowadays organisations are challenged to continuously improve their efficiency and to respond quickly to changes in their environment such as new business opportunities competition threats and evolving customer expectations It is not surprising then that organisations are paying more attention to capturing analysing and improving their work practices in a systematic manner The methods techniques and tools to do this are collectively known as Business Process Management BPM For IT departments BPM provides an opportunity to align IT systems with business requirements and to re organise exis
141. de Hode ID 10 Parent Node ID E Condition HeartRate s175 Conclusion 1 select TreatHighHeartR ate Description This worklet is used to treat patients with ver high heart rates Figure 7 23 Main Screen after Addition of New Rule rules defined for a few rule types with some tasks left undefined remember that any events that don t have associated rules for that type of event are simply ignored It follows that there will be occasions where you will want to add a new tree set to a rule set for a previously undefined rule type or add a new tree for a previously undefined task to an existing tree set Also when a new specification has been created a corresponding base rule set will also need to be created if you want to handle selections and exceptions for the new specification For each of these situations the Rules Editor provides a New Rule form which allows the definition of new rule trees with any number of rule nodes for existing tree sets where there is a task of the specification that has not yet had a tree defined for it within the tree set the definition of new tree sets for specifications that have not yet had a tree set defined for a particular rule type and entirely new rule sets for specifications that have not yet had a rule set created for them The use of the New Rule form varies slightly depending on whether it is working with a new rule set or an existing rule set This section will describe the fe
142. decrease the size of an object or objects within your specification select the object s and then use these buttons Cancellation Sets aT L These buttons allow you to include in and or exclude elements from the cancellation set of a task Zoom Options These buttons allow you to apply zoom functionality to the currently selected net From left to right reset the zoom to the actual size zoom the entire net out zoom the entire net in and zoom into the currently selected net elements 4 2 2 The Menubar This section provides a brief overview of the YAWL Menus located along the top of the YAWL Editor The majority of menu choices are also available via the menu toolbar Specification Net Edit Elements Tools View Help Specification In addition to the Specification Maintenance Verification and Analysis toolbar items this menu also contains these sub items 4 2 THE YAWL EDITOR WORKSPACE 43 e Open Recent show a list of the eight most recent specifications loaded or saved in the Editor so that one can be selected to be opened saving the trouble of navigating to it via the file open dialog If you hover the mouse over a listed file for a moment a tip will appear showing the file s full path e Print prints the entire loaded specification graphically e Update the Specification Properties such as specification name author description and so on e Update Datatype Definitions where you can define you
143. determine the most appropriate substitution The workitem is checked out of the YAWL engine and then the selected worklet is launched as a separate case The data inputs of the original workitem are mapped to the inputs of the worklet When the worklet has completed its output data is mapped back to the original workitem which is then checked back into the engine allowing the original process to continue Worklets can be substituted for atomic tasks and multiple instance atomic tasks In the case of multiple instance tasks a worklet is launched for each child workitem Because each child workitem may contain different data the worklets that substitute for them are individually selected and so may all be different The repertoire of worklets can be added to at any time as can the rules base used for the selection process Thus the service provides for dynamic ad hoc change and process evolution without having to resort to off system intervention and or system downtime or modification of the original process specification 7 1 3 The Exception Service During every instance of a workflow process certain things happen off plan That is it doesn t matter how much detail has been built into the process model certain events occur during execution that affect the work being carried out but were not defined as part of the process model Typically these events are handled off system so that processing may continue In some cases the p
144. diate Successors 9 Immediate Successors 5 Immediate Successors 2 a Reachability Set size 322 0 Duration 1450 millisecs vi Keep open when analysis completes Close Figure 4 45 Configure Specification Analysis dialog 4 8 1 Verification and Analysis Explained This section provides a brief overview of verification in YAWL Verification is concerned with the design time detection of certain undesirable characteristics in process models Extensive research has been conducted in the area of workflow verification One of the pioneers of this work 4 9 AUTOMATED TASK 89 is Wil van der Aalst He formally defined the notion of soundness as a correctness notion for workflow nets This class of Petri nets forms a predecessor of YAWL which does not support OR splits joins Multiple Instance Tasks and cancellation regions Informally speaking a workflow is sound iff 4 e The net has the option to complete That means that from every reachable state the final state where there is a single token in the output condition can be reached e The net has proper completion This means that when the output condition is marked there are no other tokens anywhere else in the net e The net has no dead tasks These are tasks that cannot be executed in any scenario For YAWL the notion of weak soundness was introduced as it can be theoretically proven that soundness is not decidable 23 For a finite state space we c
145. e 3 3 Building a Simple Workflow Example Designing a workflow typically begins with a process modelling exercise A process modelling expert sits down with a domain expert and picks their brains on how things are done The knowledge gained on the sequencing and nature of the work done is then transformed into an executable workflow Let s take a look at an example transcript between a process modelling expert Processa Maree Experta and her cousin Domainic Experta who runs the credit application department of a company called Loans R Us Processa So how does a credit application begin Domainic Well an application arrives in our office Once we receive it we validate the claim Processa What happens then Domainic We determine what credit requirements there are for the application then we seek a credit report for the applicant Processa So the credit report is requested after the credit requirements are determined Domainic Mostly Sometimes we request the credit report first Actually the order in which we do them doesn t really matter Processa Ah so both tasks could be done at the same time Domainic Yes I guess they could Processa Then what happens Domainic Once we have both the credit report and credit requirements we can tell whether we need to do a large credit approval or a small approval Only senior staff here are allowed to approve large credit applications Processa So what makes a credit a
146. e Each of those tasks needs to be associated via the YAWL Editor with the Worklet Service For example Figure 7 6 shows a simple specification for a Casualty Treatment process In this process we want the Treat task to be substituted at runtime with the appropriate worklet based on the patient data collected in the Admit and Triage tasks That is depending on each patient s actual physical data and reported symptoms we would like to run the worklet that best handles the patient s condition Worklets may be associated with an atomic task or a multiple instance atomic task Any number of worklets can be associated with i e comprise the repertoire of an individual task and any number of tasks in a particular specification can be associated with the Worklet Service Admit Triage Treat Discharge Figure 7 6 Example Top level Specification Here we want to associate the Treat task with the Worklet Service To do so right click on the task then select Task Decomposition Detail from the popup menu The Update Task Decomposition dialog is shown Figure 7 7 This dialog shows the variables defined for the task each one of these maps to a net level variable so that in this example all of the data collected from a patient in the first two tasks are made available to this task The result is that all of the relevant current case data for this process instance can be used by the Worklet Service to enable a contextual decision to be made
147. e same specification id and version is not possible and will result in an error message to this effect being displayed It is possible to have different versions of the same specification loaded at any one time e g if a specification has been updated 124 CHAPTER 6 THE RUNTIME ENVIRONMENT ee a rea arra nerea a Upload Specification Loaded Specifications Name Description _custformtest ywl 0 3 No description has been given CompletingStudent_Lodgement 0 5 Lodgement form MakeTripProcessWithMICtasks ywl 0 4 No description has been given Running Cases 53 MakeTripProcessWithMICtasks ywi 0 4 54 _custformtest ywl 0 3 Figure 6 1 Case Management but there are still cases running against the older version but new cases may only be launched for the latest version uploaded To unload a specification from the Engine simply select it and click the Unload Spec button in the Loaded Specifications panel Note that an attempt to unload a specification will fail if there are any cases still executing against it Finally the Running Cases panel show a list of all the cases currently executing in the Engine in the form case number specification name version While the list is refreshed whenever the page is loaded you may also refresh the list contents by clicking on the refresh icon located at the top right of the Running Cases panel A case can be cancelled at any time by selecting it from the list of running cases an
148. e 4 53 we can specify participant task privileges privileges that apply only for this task For example we can specify whether participants are allowed to suspend the execution of work items of the selected task More details on resource allocation and authorisation can be found in Chapter 6 4 11 Task Timer Any atomic task can be assigned a timer behaviour by right clicking on it and selecting the Set Task Timer The dialog in Figure 4 54 will appear From this dialog it is possible to set an activation type and an expiry value for the timer The timer can be activated either when a task is enabled i e is offered or allocated or when it starts These have different meanings according to the type of task manual vs automated 4 11 1 Activation on enablement e In the case of a manual task as soon as the task is enabled the timer begins and it remains live so long as the specified expiry time is not reached During this time frame the task will follow the normal resource assignment policy In other words it will be offered and can be allocated and started Once the 92 CHAPTER 4 THE EDITOR 8 oe Manage Resourcing Wizard for Atomic Task Approve Step 4 Specify System Behaviour when Allocating a Work Item The allocation process involves choosing a single participant from those who are offered a work item to actually undertake that work As you have specified that the system dynamically do this you must now select
149. e Import a specification file created with a pre 2 0 version of the Editor These files have a ywl extension e Save the currently loaded specification to file For newly created specifications this behaves the same as Save As e Save As a new file name e Close the loaded specification If there are any unsaved changes you will be prompted to save the file first before closing Specification Verification amp Analysis The first of these two buttons allows you to validate your specification against YAWL syntax and semantics while the second allows you to analyse your specification for deadlocks and other issues Net Maintenance Each workflow specification consists of one or more nets You can use these buttons to add a new Net to or remove an existing Net from your specification Edit Options jejs This group of buttons provides the standard Undo and Redo options as well as the option to delete the currently selected object s 42 CHAPTER 4 THE EDITOR Alignment Options Hompe These buttons can be used to assist with the alignment of objects within your specification when multiple objects have been selected Left to right they allow you to align selected objects based on e top edges e centres horizontally e bottom edges e left sides e centres vertically e right sides The first selected object is used as the reference to align the other objects to Object Sizes a To increase or
150. e business rules of the organisation and only that data relevant to progressing the workflow needs to be passed back into the system once they are done Because we can t transfer data directly between tasks we re also going to need a number of local parameters for the decomposition of our starting net Specifically we ll need matching ApplicationID and ApplicationAmount local parameters at the net level and another called CreditReportRef that will be used by a couple of other tasks in the workflow 90 OA Update Parameters for Atomic Task Determine Credit Requirements Input Parameters XQuery Task Variable Create Simple_Credit_Application ApplicationID text ApplicationID a Update Remove Task Variables Name Type Usage ApplicationID string Input Only ApplicationAmount double Output Only Net Variables Name ApplicationID ApplicationAmount CreditReportRet Output Parameters XQuery Net Variable Create Determine Credit Requirements ApplicationAmount text ApplicationAmount a ru Update Remove Figure 3 13 Data Mappings for Determine Credit Requirements Parameters With these local net parameters in place we now need to specify how data is passed between the net and tasks with XPath expressions The XPath expressions needed are fairly straightforward For a task input parameter we need the expression to fetch and populate the value of this parameter with that of its corresp
151. e gadget after the YAWL Worklist title e Alt Tab Names optional By default the names shown in the worklist s tabs for each queue are Offered Allocated Started and Suspended Choosing the Alt Tab Names option will instead show them as Available Assigned In Progress and Suspended e Show Suspended optional If this option is unselected the Suspended queue will be hidden Note that due to the width limits of iGoogle gadgets when the Suspended queue is shown the number of work items in each queue cannot be displayed wth the tab title 140 CHAPTER 6 THE RUNTIME ENVIRONMENT YAWL Worklist UserlD eaog apple YAWL Base URI http localhost 8080 Name Alt Tab Names iu Show Suspended W Save Figure 6 20 The Worklist Gadget s Settings dialog Click the Save button to save your settings If they are valid you will see a worklist something like the one in Figure 6 21 You can modify these settings at any time by clicking on the dropdown menu on the top right of the gadget s titlebar the small button with the dropdown arrow and choosing Edit Settings YAWL Worklist Available 1 Assigned 0 In Progress 2 362 nage Figure 6 21 The Worklist Gadget 6 7 2 Using the Worklist Gadget Each queue shows the work items available to the user specified as hyperlinks When you click on a work item link in any queue the data form for the
152. e instances When denied the default the Case Mgt form is not available to the participant A participant with default user privileges i e all unselected have access to their own work queues and may view edit their own profile A participant with Manage Cases privilege can also access the Case Mgt screen A participant with View All Work Items of Team or View All Work Items of Org Group privilege can also access the Team Queues screen All other screens can only be accessed by participants with administrator ACCESS 6 3 6 Task Privileges Task privileges or more precisely User Task privileges unlike the User privileges described above are set at design time via the Editor see Chapter 4 Section 4 10 on an individual task basis The relevant wizard panel is re shown in Figure 6 10 and a description of each task privilege is included here for completeness Broadly speaking task privileges grant or deny the ability to affect in various ways how work items are resourced after initial distribution has completed There are seven task privileges e Can Suspend When granted allows a participant to suspend the execution of a work item after it has been started e Can Reallocate Stateless When granted allows a participant to transfer responsibility for the execution of a work item from themselves to another participant with the data parameters of the work item reset to the values held when the work item was first started e Ca
153. e is set by default to a locally installed Resource Service http localhost 8080 resourceService gateway The User Name and Passwords are set to the default administrator user name admin password YAWL 4 6 3 Connecting a Decomposition to a registered YAWL Service You can use task decompositions within your workflow to make a connection to custom YAWL services that have been registered with a running engine By associating a task decomposition with a custom service all task instances based on that decomposition will be passed to the custom service at runtime for processing that is the custom service is responsible for performing the work of the task instance For example a decomposition may be set up to place an order with an external company Upon execution of any task using this decomposition data could be transmitted via a Web Service invocation to this company To have a decomposition invoke custom YAWL service do the following 1 Right click on a task the choose Task Decomposition Detail An Update Task Decomposition dialog box will appear see Figure 4 29 2 In the YAWL Registered Service Detail panel Select the required Web Service from the dropdown list of those available in the Engine 3 Click Done to finish If the Editor is connected to a valid running YAWL Engine instance the YAWL Service Dropdown Box will contain entries for all custom YAWL services the engine has registered Otherwi
154. e of Your Specification 4 4 1 Changing Flow Relations Bends and Curves You can control and improve the look of the flows between tasks by adding bends in them Go to the Study Privately Net Right click on the position in the flow where you want to add a bend which will be denoted by a small blue square in the Flow A popup menu will appear allowing you to add and remove bends as well as change the line style of the flow Create a bend somewhere towards the middle of the flow going from the Knowledge Gained condition to the Look for an Easier Book atomic task Then left click on the bend marker created and drag it out to a more desirable location You can add as many bends to a flow as you like Repeat the process for the flow between Look For an Easier Book and Read A Book tasks see Fig ure 4 16 Relocation You can reconnect flow relations to other elements of a net or different points on the same element by se lecting the flow and dragging one of its connecting ends from one net element to another If a connection is possible at some other element connection points will become visible as described earlier Release the mouse button to attach the flow to its new home Take the current flow relation and move it from the top of the task to its side as depicted in Figure 4 16 Adding Labels It is also possible to add labels to flows To do so double click on a flow A small
155. e prioritised last in the order becomes the default flow To update the flow detail of a task that has a split right click on the task and choose Update Flow Detail The Flow Detail dialog appears which list the flows coming out of the split and each flow s corresponding Predicate or flow expression The arrowed buttons to the right of the list allow you to reorder the evaluation sequence of the predicates so that the default predicate the one you want to activate when all others fail can be placed at the bottom of the list Carefully ordering the evaluation sequence is especially important when dealing with an XOR split because only the first that evaluates to true will be activated and any following flows will be ignored The currently selected flow in the dialog will be identified by being highlighted green in the Net Figure 4 33 To specify a predicate for a particular flow select the flow from the list and click on Predicate Enter a predicate as a boolean XQuery expression and choose Done 4 5 ADDITIONAL SPECIFICATION FEATURES 13 MyCareer Study Privately ij Attend_University H Begin My Get a Job Career Career University Started ii Boo Flow detail for Atomic Task Begin My Career Target Task Predicate Attend University number My Career score text gt 65 Study wendy Pravataiy ciate s Predicate Privately ud l The bottom most flow will be set to trueQ and used as the def
156. e you are adding the new rule to is of Selection type or one of the exception types Adding a conclusion for a Selection rule is explained below Refer to the Creating a New Rule Set and or Tree Set section below for details on adding a conclusion for the exception types 7 5 5 Adding a Conclusion Selection Rule Type For a Selection rule tree when the New button is clicked a dialog is displayed that comprises a drop down list containing the names of all the worklets in the worklets folder of the worklet repository refer Figure 7 19 An appropriate worklet for this rule may be chosen from the list or if none of the existing worklets are suitable a new worklet specification may be created Clicking the New button on this dialog will open the YAWL Editor so that a new worklet specification can be created When defining the new worklet bear in mind that to pass data from the original work item to the worklet the names and data types of the variables to be passed must match those of the work item and be created as net level variables in the worklet specification Also all new worklets must be saved to the worklets folder of the repository so that the Worklet Service can access it TIP You may choose more than one worklet in this dialog simultaneously by holding down the Ctrl or Alt keys while clicking the mouse in the usual Windows way If you choose several worklets when this rule is invoked for a process at runtime all of the workle
157. eRequired Update Parameters for Atomic Task book flight Input Parameters XQuery Task Variable do itinerary seqment customer text customer do_itinerary segment leg leg do_ itinerary segment startDate text startDate do_itinerary_segment endDate texti endDate Net Variables Task Variables Name Type Usage Name Type Usage customer string Input Output customer string Input Only leg legType Input Output leg legType Input Only startDate date Output Only startDate date Input Only endDate date Output Only endDate date Input Only flightDetails string Input amp Output flightDetails string hotelDetails string Input amp Output carDetails string Input Output subTotal double Input Output serviceRequired serviceType Local Output Only Output Parameters xQue Net Variable book flight flightDetails text flightDetails Figure 5 28 Parameter definition for task book flight 5 ra 5 5 ILLUSTRATIVE EXAMPLES B Update Parameters for Atomic Task prepare pay Input Parameters IUE Task Yariable trdo itinerary segment customer texti customer i rdo itinerary segment Elightbhetaila texti Elightbetails fdo itinerary seqment hotelDetails textl hotelDetails ido itinerary Sellen carDetails texti Net Variables Mame
158. el Figure 4 3 Specification Properties Dialog 2 Position your mouse just to the right of the Input Condition the gt symbol and click the left mouse button once to place an Atomic Task 3 Set the decomposition of this task by right clicking on the Atomic Task and choosing Select Task Decomposition You should see a dialog as per Figure 4 4 8 N90 Atomic Task ee e Create Set decomposition to Done Cancel Figure 4 4 The Select Task Decomposition dialog 4 Press the Create composition s label button and in the following Update Task Decomposition dialog enter the de See Section 4 5 5 for a full explanation of this dialog s features Set the label to Begin My Career and click the Done button 5 Note that by default a task takes on the label of the decomposition that it is associated with several tasks are allowed to share the same decomposition Once you ve created your task you are free to relabel the task to whatever you like This can be done by right clicking on the task and choosing Set Label from the pop up menu This will not change the name of the decomposition with which the task is associated 6 Connect the Input Condition to your Atomic Task as shown in Figure 4 5 by finding the flow connectors that appear as small blue boxes as you hover your mouse over the sides of the objects Hold the left mouse button down over a flow connector and draw a line by dragging the
159. elements data transfer passing data between workflow components and exchanging information with the environment data related issues such as data based conditional routing and handling of multiple instance data Readers are assumed to have knowledge of YAWL and its supporting tools the YAWL engine see Chapter 6 and the YAWL editor see Chapter 4 5 2 Data Visibility In YAWL all data are represented as XML documents Figure 5 1 depicts an example of a YAWL net specifying a simple trip booking process The data at the net level are written in an XML document with a root element named PerformBooking i e the name of the net while the data at the task level are written in an XML document for each task Next data elements are stored in variables There are net variables for storing data that need to be accessed and or updated by tasks in a net and task variables for storing data that needs to be accessed and or updated only within the context of individual execution instances of a task Note that the task variables of a composite task are conceptually the net variables of the corresponding subnet YAWL applies strong data typing Data types are defined using XML Schema The YAWL Editor provides a list of all 46 XML Schema simple data types for variable definition These include some basic types such as boolean string double decimal long integer date in the format of yyyy mm dd and time hh mm ss Based on the above t
160. elevant to an organisation In the YAWL model each position may belong to zero or one org groups Further like roles an org group may belong to a larger more general org group for example the groups Marketing and Sales may each belong to the more general Production group Org groups are often also based on location Like positions org groups may be included in a filter defined at design time that is run over the distribution set for a task at runtime While the descriptions of the various entities in the YAWL model above discuss the typical uses of each it should be clear that they represent at the most basic level merely various ways to group participants The main point of distinction between them is that only roles can be used to populate a distribution set in the Editor the other three may be used to perform filtering over the set The Org Data Screen contains four tab pages one for each of org entities listed above The methods used to maintain the data for each entity is similar on each of these four pages To Add a new entity click the New button which will display an Add New input field see Figure 6 6 128 CHAPTER 6 THE RUNTIME ENVIRONMENT Tver Ea rano an nn samme ve ors even tooo gt Capabilities Positions OrgGroups Description Belongs To may perform the duties of Carrier Admin Officer making coffee for their Client Liaison superiors Courier Finance Officer Junior Supply Officer Notes O
161. ent parts of the organisation they have the same data requirements and can both use the same decomposition which we ll call Credit Approval We have a resulting parameter requirement per decomposition as per figure 3 10 Decomposition Type Designation Receive and Validate Application ApplicationID string output Determine Credit Requirements applicat ionID input ApplicationAmount output Obtain Credit Report HEpEtcabnout sa CreditReportRef output ApplicationID input Credit Approval CreditReportRef input ApplicationAmount input Figure 3 10 Parameters Required for Task Decompositions To give you some idea of how this might look figure 3 11 is a screenshot of the Editor showing the decom position for the task Determine Credit Requirements with an input parameter ApplicationlID and an output parameter AppplicationAmount When running our specification a participant will be offered a work item 34 CHAPTER 3 GETTING STARTED WITH YAWL for an instance of this task They will be given an application identifier and will work outside of the system eventually generating an application amount for that application Figure 3 12 shows how the default worklist handler displays an instance of this task for a participant to work with 00O YAWLEditor Users adamsmj Documents research temp gs2 yawl B 2 Bla e 2 vle Gm gt e e m a s s mw OdG 6 Simple Credit Application Ogee it Update Task Decomposition Determine
162. enu allows workflow designers to analyse their specifications A number of potential problems with a work flow can be automatically spotted with analysis Examples include spotting potential deadlock situations unnecessary cancellation set members and unnecessary or join decorators at run time or joins require sig nificant processing effort and should be removed or replaced with other join types if they are not actually needed A configuration dialog for specification analysis is available via the Tools menu Configure Specification Analysis see Figure 4 44 Note that many of the options are disabled by default since they are resource intensive and may take some time to complete for large and or complex workflows It is recommended that analysis of such specifications not be done incrementally but rather at planned checkpoints during specification development Because analysis make take a long time and is very resource intensive it may appear that the Editor has frozen during an analysis although it is very unlikely that this will actually be the case To provide some feedback about the progress of the analysis a dialog will appear which shows updates and messages see Figure 4 45 The dialog includes a checkbox that when checked will keep the dialog open after the analysis completes so that the messages may be noted This functionality can also be controlled via a setting in the Configure Specification Analysis dialog see Figure 4 44
163. er convenience two XQuery buttons are supplied to generate XQuery expressions from available task variables The add XQuery of element s content button will return just the content of the XML element for this variable which is useful for simple state transfer between two variables of the same XML Schema type and expected to be the typical button that users will start out with The other button add XQuery of entire element will return the entire XML element of the selected variable which is useful for times when you want to create a complex type expression from individual variable elements Experience with XMSchema and XQuery are necessary to understand the effects this button will have on runtime YAWL engine state From the list of task variables select the SubjectCode task variable and click add XQuery of element s content From the list of net variables select the SubjectCode variable Click Done Create another Task Parameter and map the task StudentNumber to the net variable of the same name using this technique Click Done and Done again These Parameters were set up to demonstrate a simple transfer of state from a net to a task and back to the net Perhaps the task would allow a user to change the values of one of the variables which would eventuate in the net s values changing The Update Parameters dialog box should appear as in Figure 4 32 Notes about parameters e For simple assignments such a
164. erences In this section the discussion of rule sets applies to both services except where indicated 7 5 1 Worklet Rule Sets Any YAWL specification may have an associated rule set The rule set for each specification is stored as XML data in a disk file that has the same name as the specification but with an xrs extension XML Rule Set All rule set files are stored in the rules folder of the worklet repository For example the file Casualty_Treatment xrs contains the worklet rule set for the Casualty_Treatment yawl YAWL process specification Figure 7 11 shows an excerpt from that file A rule set for a specification consists of a collection of rule trees Each rule tree represents a set of modified Ripple Down Rules RDR which maintains a rule node hierarchy in a binary tree structure When a rule tree is queried it is traversed from the root node of the tree along the branches each node having its condition evaluated along the way If a node s condition evaluates to True and it has a true child then that child nodes condition is also evaluated If a nodes condition evaluates to False and there is a false child then that child nodes condition is evaluated When a terminal node is reached i e a node without any child nodes if its condition evaluates to True then that conclusion is returned as the result of the tree traversal if it evaluates to False then the last node in the traversal that evaluated to True is returned as t
165. es for the Bob variable as shown in Figure 7 38 you will have to click the add button twice to get three input fields Make sure you enter the values one two and three without the quotes and in any order Complete the form 178 CHAPTER 7 THE WORKLET SERVICE Edit Work ltem 1 4 ony ser Figure 7 36 Discharge Workitem with Data Mapped from TreatFever Worklet Create_list_items i Verify_list Show_list Figure 7 37 The wlistMaker Specification Start and edit the Create List Items workitem Since the values have already been entered there is no more to do here so click the Complete button to continue The next task is Verify List which has been associated with the Worklet Service Since this task is a multiple instance atomic task three child workitem instances of the task are created one for each of the Bob values entered previously The Worklet Service will determine that it is a multiple instance atomic task and will treat each child workitem instance separately and will launch the appropriate worklet for each based on the data contained in each Since the data in each child instance is different in this example the Worklet Service starts three different worklets called BobOne BobTwo and BobThree Each of these worklets contains only one task Go to the Work Queues page There are three workitems listed each one the first workitem of a separate case see Figure 7 39 Go to the Ca
166. eter definition of task ReceiveSSN It can be observed that this task has an output only variable called ssn This variable requests social security number from the client and as specified in the output parameter definition it then passes the data to net via XQuery ReceivedSSN ssn text which can be generated automatically by clicking the add XQuery of element s content button in the Update Net Parameter dialog Figure 5 8 shows the flow definition at task ReceiveSSN The predicate for the flow leading to task Report Fault is starts with CreditRatingProcess ssn text 0 It returns true if the string conveyed by variable ssn starts with string string is an inbuilt XPath boolean function It returns true if the first argument string starts with the 5 5 ILLUSTRATIVE EXAMPLES 105 B Update Net Variable rating Standard Extended Attributes Harme rating Type double E Update Net Decomposition Credit Rating Process pee Loca Net Decomposition Label Credit Rating Process Initial Value 560 Net Decomposition Variables Name Type Usage Done Cancel san string Local rating doub le Local fault string Local Update Net Variable fault Standard Extended Attributes Name fault Type siring Usage Local Initial Value Bankeuptey tt tt sSY Done Cancel Figure 5 6 Net variable definitions
167. ever you have selected a number of net elements pressing one of the arrow keys will move the selected elements in the direction of the arrow key and pressing the CTRL key plus the A key will select all the elements in the currently selected net 4 4 3 Changing Font Size You can change the size of the font used to label tasks and conditions 1 Change the font size by clicking on the View Menu and choosing the Label Font Size option 2 Change the font size to that desired The specified font size applies to all text drawn on the canvas 4 4 4 Changing Task Icons You can add or change the icon that is shown on atomic tasks 1 Select any single atomic task in your workflow The palette will expand to include a task icon tree depicted in Figure 4 13 where you can an icon from the tree to the task You are free to assign any icon Icons have no runtime effect on the engine and are provided simply to make specifications more easily understood by people looking at the specification in the editor 4 4 5 Using Custom Icons Workflow designers can plug in and use their own icons for specification design Icons must be of the PNG file format and be a maximum of 24 x 24 pixels to render properly within editor task boundaries When the editor starts it checks the installation folder for the plugin directory lt editor_installation_path gt YAWLEditorPlugins TaskIcons for user defined icons and if found adds them into the plu
168. f 100 per ticket and 12600 as the number of tickets sold and then complete the workitem Figure 7 44 Notice that the entered number of tickets sold 12600 is slightly more than 50 of the venue s seating capacity 25000 The next workitem Do Show does have a pre item constraint rule tree and so when it becomes enabled the rule tree is queried The effective composite rule for Do Shows pre item tree as viewed in the Rules Editor is In other words when Do Show is enabled and the value of the case data attribute TicketsSold is less than T5 of the seating capacity of the venue we would like to suspend the workitem run the compensatory worklet ChangeToMidVenue and then once the worklet has completed continue or unsuspend the workitem Following the logic of the ripple down rule if the tickets sold are also less than 50 of the capacity then we want instead to suspend the workitem run the ChangeToSmallVenue worklet and then unsuspend the workitem Finally if there has been less than 20 of the tickets sold we want instead to suspend the entire case run a worklet to cancel the show and then remove i e cancel the case In this example the first rule s condition evaluates to true for a Tickets Sold value of 12600 and a seating capacity of 25000 so the child rule node on the true branch of the parent is tested Since this child node s condition evaluates to false for the case data the rule evaluation
169. fications and the creation of new rule sets It is a NET based application so has the following requirements 7 0 WORKLET RULE SETS AND THE RULES EDITOR 159 e Operating System Windows 98SE or later e The Microsoft NET framework any version If you dont have the framework installed it can be downloaded free from Microsoft ra When the Rules Editor is run for the first time the following dialog shown in Figure 7 13 is displayed Rules Editor First Time Configure Welcome to the Worklet Rules Editor Please enter the file paths to the resources listed in the next dialog Figure 7 13 Rules Editor First Time Use Message Clicking OK shows the Configuration dialog Figure 7 14 where the paths to resources the Rules Editor uses are to be specified Some default paths are shown but can be modified directly or by using the browse buttons where available he following paths must be specified e Worklet Service URI the URI to the Worklet Service The default URI assumes it is installed locally If it is remote to the computer running the Rules Editor then that URI should be entered ensuring it ends with workletService e Worklet Repository the path where the worklet repository was installed The default path shown assumes the Rules Editor was started from the rulesEditor folder of the repository If it was started from another location specify the actual path to the repository by editing the path or browsing to
170. gin branch of the task icon tree widget of the editor s palette Sub directories are supported and will form new sub trees of the same name when the plugin sub tree is being created If an icon cannot be found that was previously used for a specification a special broken icon will render in its place as depicted in Figure 4 18 60 CHAPTER 4 THE EDITOR Figure 4 18 A task specifying an icon that the editor cannot locate 4 5 Additional Specification Features 4 5 1 Cancellation Sets Cancellation Sets allow you to nominate any number of tasks conditions and or flow relations which when they join two tasks directly contain an implicit condition that is not visible on the net for cancellation upon the completion of a specified task That is once a specified task has completed execution in a workflow instance all other net elements within that task s nominated cancellation set if any are deactivated To create a Cancellation Set for a task 1 First select the task that will initiate the Cancellation Set 2 Right click on the task then choose View Cancellation Set from the context menu The task will be fill with a grey colour to indicate that this is the task that owns the cancellation set currently on view Create the Purchase Book specification as shown in Figure 4 19 In this example we are going to purchase a book by placing an order with three different sellers as soon as the first seller fills t
171. gine A semantic error may result in a Schema Validation Problem and the execution of the process may fail 5 4 Data related Issues 5 4 1 Data based Conditional Routing When tasks have XOR or OR splits which branch to choose is determined by conditional expressions asso ciated with flows These conditions are boolean expressions that involve data within the process The data may determine the evaluation results of the conditions and therefore influence the operation of the process In YAWL the branching conditions are specified as XPath boolean expressions in the flow detail for tasks with XOR or OR splits The branches flows whose conditions predicates evaluate to true will be executed by the YAWL engine all true branches for an OR split the first true branch from an XOR split Also for each task with XOR or OR split there is always a default flow that will be taken if none of the other flow predicates evaluate to true We consider separately below tasks with XOR splits and the tasks with OR splits As an example Figure 5 4 shows the XPath expression which is specified at task Decide for choosing the branch of Book Car in the PerformBooking process depicted in Figure 5 1 For a task with XOR split all conditional flows are specified in a list and their predicates are evaluated in the same order as they are present in the list Since an XOR split allows only one flow to be chosen once the en
172. gine reaches a flow predicate that evaluates to true the corresponding flow will be chosen and the rest of the list will be not be evaluated However if the engine reaches the bottom of the list the bottom most flow will always be chosen as the default and it is not necessary to evaluate the predicate associated with that flow Therefore the default flow of a task with XOR split is similar to the concept of an otherwise clause defined in most programming languages For a task with an OR split e g the task Decide in Figure 5 4 all flows with their predicates are also present in a list However an OR split requires that all flows whose predicates evaluate to true are taken Therefore the engine will evaluate all flow predicates and only if none of them evaluate to true will the bottom most flow be taken as the default despite the false evaluation result of its predicate Note In Chapter 4 Section 4 5 8 illustrates how to specify flow predicates for tasks with XOR or OR splits in the YAWL Editor Two things are worth noting 4XML Path Language XPath 1 0 W3C Recommendation 16 November 1999 5 4 DATA RELATED ISSUES 103 XPath boolean PerformBooking requireCar text true lt PerformBooking gt B m lt requireCar gt true lt requireCar gt lt requireHotel gt true lt requireHotel gt lt requireFlight gt false lt requireFlight gt lt PerformBooking gt Decide Figure 5 4 XPath
173. gn of workflow models a workflow engine to support the execution of workflow models and at least one worklist handler Workflow Engine The runtime component of a workflow system responsible for determining which tasks need to be performed and when for maintaining execution logs and for delegating the performance of tasks to software applications services or to a worklist handler Case Also known as Workflow Instance A specific instantiation of a workflow model as a result of an event For example an order management workflow is instantiated every time a new order arrives Each of these orders leads to a different case Task Also known as Activity A description of a unit of work that may need to be performed as part of a workflow Workflow models are composed of tasks Generally a task may be either manually carried out by a person or automatically by a software application 2See https sourceforge net docman group_id 114611 3 3 BUILDING A SIMPLE WORKFLOW EXAMPLE 25 Work item Also known as Task Instance A particular instance of a task that needs to be performed as part of a given workflow instance Worklist A list of work items Worklist Handler Also known as a Task Management Service A software component that manages work items issued by a workflow engine and that assigns prioritises and presents these work items to human participants according to policies that may be configured in the workflow model and or at runtim
174. gs and external data sets 194 CHAPTER 7 THE WORKLET SERVICE 7 8 Sample Log generated by Walkthrough C In the following every line started with the date which has been omitted for readabilty reasons Similary Exxceptionservice has been abbreviated to ES and WorkletService to WS 12 16 31 875 INFO ES HANDLE CHECK CASE CONSTRAINT EVENT 12 16 31 984 INFO ES Checking constraints for start of case 20 of specification OrganiseConcert 12 16 32 093 INFO ES No pre case constraints defined for spec OrganiseConcert 12 16 32 109 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 16 32 156 INFO ES Checking pre constraints for workitem 20 BookStadium_5 12 16 32 281 INFO ES No pre task constraints defined for task BookStadium 12 28 17 968 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 28 18 000 INFO ES Checking pre constraints for workitem 20 Sell Tickets_3 12 28 18 015 INFO ES No pre task constraints defined for task Sell Tickets 12 28 18 078 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 28 18 093 INFO ES Checking post constraints for workitem 20 1 BookStadium_5 12 28 18 093 INFO ES No post task constraints defined for task BookStadium 12 56 08 000 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 56 08 015 INFO ES Checking pre constraints for workitem 20 DoShow_4 12 56 08 140 INFO ES Workitem 20 DoShow_4 failed pre task constrain
175. h Kees van Hee is highly recommended reading 4 A recent textbook on Business Process Management BPM which covers the original control flow patterns and also YAWL was written by Mathias Weske 22 This textbook also covers other approaches such as the modelling standard BPMN note that the BPMN2YAWL tool can convert these specifications to YAWL On the YAWL web site yawlfoundation org it can be seen how the original control flow patterns can be realised in YAWL follow the link on Resources and then click patterns For control flow patterns in new YAWL the reader can consult appendix A 1 of Nick Russell s PhD thesis 20 If you would like to know more about how verification of YAWL specifications really works we refer you o 21 and to 23 This work forms the theoretical basis of how the verification mechanisms are realised in the YAWL editor In depth discussion of YAWL s exception handling framework from a conceptual point of view can be found in 20 16 and from an implementation aspect in 7 8 The YAWL s worklet approach to dealing with on the fly changes to workflows has been discussed in 7 9 The reader that is interested in declarative specification of workflow is referred to 13 On the Declare web site declare sf net the Declare service for YAWL can be downloaded Further documentation about this approach can also be found there YAWL has a close link to the Process Mining environment ProM 3 www pro
176. h a single rule see Figure 7 52 Notice the rules condition isNotCompleted this e isNotCompleted is an example of a defined function that may be used as or as part of conditional expressions in rule nodes 7 6 WALKTHROUGH USING THE WORKLET SERVICE 187 Fill Order Receive Archive Payment Figure 7 50 The Timeout Test 3 Specification aoe Set Timer Detail for Atomic Task Receive Payment Fal Task is required to timeout Timeout dynamically via net variable 7 J at the time of 10 07 2009 13 6 00 5 39 5 after a duration of PT5S e a nr h F Timer begins upon work item enablement fa upon work item starting Done Cancel Figure 7 51 The Set Timer Detail dialog for the Receive Payment task e this is a special variable created by the Worklet Service that refers to the workitem that the rule is defined for and contains amongst other things all of the workitem s data attributes and values Tip The Worklet Service provides developers with an easily extendible class where functions can be defined and then used in conditions See Appendix 7 7 for more information about defining functions In this case the condition tests if the workitem Receive Payment has not yet completed i e if it has a status of Fired Enabled Executing or Suspended If it hasn t completed thus payment for the order has not yet been received then the conclusion will be executed as an exception handling process i
177. hat was selected IMPORTANT The rejection of a selected worklet is a legitimate and expected occurrence Each rejection allows for the addition of a new exception rule or a rule on the true branch of its parent thus creating a learning system where all events are handled online When the new rule is added as a result of the rejection it will return the correct worklet for every subsequent case that has a similar context Thus rejecting a worklet actually refines the rule set for a specification To reject a selected worklet go to the Case Mgt screen and select in the list of running cases the worklet you wish to reject Then click the Reject Worklet button see Figure 7 47 You will be redirected to the Reject Worklet Selection screen another Worklet Service add in screen Figure 7 54 This screen displays the Specification and Case ID for the selected worklet Enter a proposed title or name for the new worklet and an explanation of reason for the rejection in plain text and then submit the form e008 Worklet Service Reject Worklet Selection Gr ta ant E http localhost 8080 workletService rejectWorklet caselD 34 oy 3 ics Google Oika we 4G Reject Worklet Selection Case ID Specification ID 34 TreatWound Please complete each of the fields below Proposed Title Reason for Rejection Cancel Submit YAWL is distributed under the LGPL Figure 7 54 Reject Worklet Sele
178. he name of a role Participants Roles Net Parameters Di ELAI a a a Peter Clemenza pc i Junior Supply Officer Name Refers to Stefano Clemenza sca Order Fulfilment Manager Don Vito Corleone dvc PO Manager Fredo Corleone fc Senior Credit Officer Mama Corleone mac Senior Finance Officer Michael Corleone mc Senior Supply Officer Sonny Corleone 5c Shipment Planner Carmine Cuneo cc Supply Admin Officer Don Carmine Cuneo idee Warehouse Admin Officer Johnny Fontaine jf hi Warehouse Officer Unselect All Unselect All lt Back gt Next Finish Figure 3 8 Assigning a Role used to describe inbound and outbound mappings Accordingly the parameters of nets and tasks in YAWL XQuery expressions for data transfer in such cases 3 4 ADVANCED WORKFLOW CONCEPTS 33 are all encoded as XML documents Net Instance Task Instance Outbound Mappings Tnbound Mappings Output Output Output Figure 3 9 Example Data Transfer between a Net and Task Figure 3 9 depicts example data transfers over the lifetime of a task instance The task s decomposition defines two input parameters and three output parameters When the task instance starts values for its input parameters are populated by executing the input mappings for the task which are then passed onto the task s designated YAWL Service The default worklist handler is an example of an external se
179. he order we want to cancel the other two orders To achieve this we create a cancellation set for each Order task that includes the other two Order tasks We will step through creating a cancellation set for the Order from Amazon task the other two are created in a similar manner Order from Amazon Order from Booktopia Get Book Details Order from Bookfinder Figure 4 19 The Purchase Book specification Right click on Order from Amazon and choose View Cancellation Set 3 Next choose a task condition or flow and thus an implicit condition to add to the Cancellation Set Hold down the shift key to select more than one object for cancellation 4 5 ADDITIONAL SPECIFICATION FEATURES 61 Select the Order from Booktopia and Order from Bookfinder tasks and the flow relation preceding each of them Click on the Add Selected Items to Visible Cancellation Set button al on the Menu Toolbar Items will be given a red border to indicate they belong to the cancellation set of the grey filled task see Figure 4 20 Add the selected tasks and flow relations to the cancellation set Once you have established the cancellation set you can right click on the cancellable task and reselect View Cancellation Set to toggle off the cancellation set view Order from Amazon Order from Booktopia Get Book Details Order from Bookfinder Fig
180. he result The root node Rule 0 of the tree is always a default node with a default True condition and conclusion and so can only have a true branch Effectively each rule node on the true branch of its parent node is an exception rule to the more general one of its parent that is a refinement of the parent rule while each rule node on the false branch of its parent node is an else rule to its parent or an alternate to the parent rule For example see the selection rule tree for the Casualty Treatment specification Figure 7 12 The condition part is the rule that is evaluated and the conclusion is the name of the worklet selected by that rule if the condition evaluates to true For example if the condition fever true evaluates to true then the TreatFever worklet is selected via node 1 if it is false then the next false node is tested node 2 If node 2 is also false then node 3 is tested If node 3 evaluates to true then the TreatAbPain worklet is selected except if the condition in its next true node node 7 also evaluates to true in which case the TreatLabour worklet is selected One worklet rule set file is associated with each specification and may contain up to eleven sets of rule trees or tree sets one for selection rules and one for each of the ten exception types Three of the eleven relate to case level exceptions i e CasePreConstraint CasePostConstraint and CaseExternalTrigger and so each of
181. he users can also supply their own XML Schema to define more complex data types Figure 5 2 shows the XML schema of a user defined data type for element CustInfo which consists of both customer name and target start date for the booking trip process depicted in 6 Data usage is also part of the variable definition There are input and output variables input only or output only variables and local variables In general data are written to input variables and read from output variables Local data usage is applicable to net variables only The local net variables are used to store data that can be manipulated only internally within the scope of the corresponding net Finally a net variable may be assigned an initial value at design time Further details will be given in the next section on data transfer XML Path Language XPath 1 0 W3C Recommendation 16 November 1999 XQuery 1 0 An XML Query Language W3C Working Draft 4 April 2005 99 100 lt PerformBooking lt custinfo gt lt requireCar true lt requireCar gt lt requireF light falses requireF light lt totalPrice s _ lt PerformBooking gt Net PerformBooking lt Custinfo gt lt CustName gt M Twain lt CustName gt lt T argetStantD ate gt 2005 12 07 lt T argetStartD ate gt lt Custinfo gt lt Decide gt lt complexType gt lt schema xmins http Anmaw wG org 200 1 XMLS chema gt lt element name Decide gt lt sequence gt
182. iables required for the successful operation of the service e SMSMessage The message text to send to the mobile device e SMSPhoneNumber The phone number of the mobile device to call and e SMSReplyMessage The message text that is returned from the mobile device When invoked at runtime the SMS Service will logon to the SMS Gateway provider using the userid and password supplied via the web xml file then if successful will pass the SMSMessage and SMSPhoneNumber values to to the service s Send URI The SMS Gateway provider will send the text message to the mobile device identified by the phone number It will then wait for a reply message from the device which it will pass back through the SMSReplyMessage variable which can then be mapped back to a corresponding net level variable in the process for display in a subsequent task 8 3 TWITTER SERVICE 199 86 O8e Update Task Decomposition Extended Attributes Task Decomposition Label SendTxt Task Decomposition Variables Name Type Usage Create SMSMessage string Input Only __ gt gt SMS5PhoneNumber string Input Only Update SMSReplyMessage string Output Only Remove YAWL Registered Service Detail YAWL Service 5M5 Service Ea External Interaction _ Automated Set Codelet Done Cancel i ued Figure 8 2 Task Decomposition Dialog for SMS Service associated task 8
183. iefly described below Offer The point at which it is decided that a number of participants could undertake the work item Allocation The point at which one of the participants offered the work item is nominated to do that work item Start The point at which the participant allocated a work item begins working on it Offering a work item for this task to a number of participants is to be done by User System Allocating a work item for this task to one of the offered participants is to be done by User System Starting an allocated work item of this task is tobe done by User System lt Back gt Next Einish Figure 4 49 Step 1 of the resource management wizard Step 2 In Step 2 shown in Figure 4 50 we can select an initial set of resources called the distribution set that will be offered work items of the selected task at runtime by the System The distribution set may consist of any number of participants and or roles These can be picked from the relevant lists in this dialog multiple selections are supported Additionally in the Net Parameters panel you may nominate one or more net level variables that at runtime will contain a value of the userid of a participant or the name of a role that is deferred allocation For a variable to appear in the Net Parameters panel it must be of type string and usage Input amp Output or Input Only Note that all net level variable
184. ierarchy of executing worklets may sometimes exist It is also possible to recursively define worklet substitutions that is a worklet may contain a task that while certain conditions hold true is substituted by another instance of the same worklet specification that contains the task Any number of worklets can be created for a particular task For the Casualty Treatment example there are initially five worklets in the repertoire for the Treat task one for each of the five primary conditions that a patient may present with in the Triage task Fever Rash Fracture Wound and Abdominal Pain Which worklet is chosen for the Treat task depends on which of the five is given a value of True in the Triage task How the Worklet Service uses case data to determine the appropriate worklet to execute is described in Section 7 5 2 7 4 Using the Worklet Exception Service In the previous Section we saw how the Worklet Service adds dynamic flexibility to a usually static YAWL specification by substituting tasks with contextually chosen worklets at runtime The Worklet Exception Service leverages off the worklet framework to also provide support for the myriad exceptions that may occur during the execution of any process instance Every process instance no matter how rigidly structured will experience some kind of exception during its execution While the word exception conjures up ideas of errors or problems occurring within the executing
185. ill help you to become familiar enough with YAWL that you feel comfortable designing and executing at least simple workflows For more information you may refer to other chapters in this manual the technical manual or the various academic papers and case studies available in the YAWL Sourceforge web site 3 2 Terminology Before jumping in and getting our hands dirty with a real workflow example let s briefly agree on some basic terms Business Process A set of interdependent activities that need to be performed in response to a business event to achieve a business objective Typical examples of business processes are complaint handling order to cash or credit card approval Workflow Application A software application that co ordinates the tasks data and resources that com pose a business process in whole or part Sometimes the term workflow is used as a shorthand for workflow application Workflow Specification Also known as Workflow Model A description of a business process to the level of detail required for its deployment into a workflow engine A workflow specification defines which tasks should be performed under which conditions and in which order which data documents and resources are required in performing each task etc Workflow System A system that can be used to develop and to run a workflow application A workflow system usually includes a process editor to support the desi
186. imer dialog for an atomic task timer has already expired and immediately complete the work item before it has a chance to appear on a worklist e Using a Duration value A Duration is one of the built in simple XML Schema data types and is 94 CHAPTER 4 THE EDITOR used to represent a period of time When a Duration type is used as a timer expiry value the timer will expire exactly when that period of time has passed since the work item was enabled or started depending on when it is set to activate To set a specific duration choose the after a duration of radio button on the Set Timeout Detail dialog Figure 4 54 and enter the required value A Duration value is expressed in the following form PnYnMnDTnHnMnS All values start with P for Period followed by a non negative number of years months days then T for time followed by a non negative number of hours minutes and seconds The seconds value can have a decimal point and as many digits following the point as required e g to specify fractions of a second Any zero value parts can be omitted Valid examples P1Y4M3DT23H55M1 5S8 P2M3D PT10S Care should be taken when specifying a duration for example P2M may mean a different number of days depending on what month it is started in In addition to the methods described above timer parameters may also be set at runtime via a declared variable of type YTimerType so that values can be supplied and late bound to a task
187. imply double clicking on the installation file Installation After being greeted by the Welcome screen and pressing Next you ll see the License Agreement page The license agreement contains the Gnu Lesser General Public License Version 2 1 the Apache License Version 2 0 the BSD License and Sun s Binary Code License Agreement You need to accept the agreements to continue the installation In the next step you are given the choice to update YAWL but only if the same YAWL version is already installed to do a standard installation or to install YAWL and conduct a comprehensive configuration of its third party components If it is chosen to update YAWL existing configurations are used to update the current YAWL installation zox YAWL Installation v Choose the type of YAWL installation Update Update existing YAWL environment and keep setting Standard Install YAWL environment with default setting Custom Local remote installation configuration of the YAWL environment i Cancel Figure 2 5 Type of YAWL4Enteprise Installation The next step is to select the installation directory and to choose a Java installation The dialogue box in figure 2 6 will only appear if Java greater or equal 1 5 is detected on your system loxi Please select the Javaftm Runtime to use sun 1 6 0 C Program Files Java jre1 6 0_07 binjjava exe OK Cancel Figure 2 6 Select Java Version Within the next steps the installa
188. in the Menu and choose Create Specification This will create a blank Net called New Net 1 which will be by default the starting net of the workflow For details on selecting a starting net consult Section 4 3 6 2 Click on Specification in the main Menu and choose Update Specification Properties A screen as per Figure 4 3 will appear Alter the specification s properties as you feel appropriate 3 Rename this Net by clicking on the Net Menu and choosing Update Net Detail 4 Enter the new name of the Net in the Decomposition Label field then click the Done button Decomposition Variables will be explained later in Section 4 5 3 Change the name of the Net in the Decomposition Label to My Career This Net will be the primary net for our scenario 5 You are now ready to start drawing your specification 4 3 2 Atomic Tasks 1 Click on the Add an Atomic Task button o in the Workflow Elements Panel or right click in an empty area of the canvas and choose Atomic Task 4 3 CREATING YOUR FIRST SPECIFICATION aon 4T Update Specification Properties Specification ID Specification Name ManualExample Manual Example ple specification with propertie Specification Description I nex Specification Author Version Number 0 3 Specification valid from seas the date of 23 07 2008 always Specification valid until Z the date of 23 07 2008 Done Canc
189. ine which returns the list of services currently registered with it Therefore the Editor must first establish a connection to a running Engine On Editor startup a connection to a running Engine is attempted If successful the Engine connection icon at the left of the status bar will turn green If unsuccessful perhaps because the Engine is not running or the connection parameters are incorrect the connection icon will show red After the Editor has started an Engine connection may be performed via the Tools menu To establish a connection with a running YAWL Engine 1 Click the Tools Menu and choose the Engine Connection Settings item 2 From the resulting dialog Figure 4 39 accept the default values or enter the following engine details e YAWL Engine URI e Administrator s User Name e Administrator s Password 0 0 YAWL Engine Connection Settings YAWL Engine URI http localhost 8080 yawl ia User Name admin e 7 Test Connection Successfully connected to a running YAWL engine Done Cancel Figure 4 39 Specifying the YAWL Engine connection detail The YAWL Engine URI value is set by default to a locally installed Engine http localhost 8080 yawl ia The User Name and Password are set to the default administrator user name admin password YAWL As a user convenience a button called Test Connection is supplied which will attempt to connect to a running engine with the detail supplied
190. ing them from the list after it has been actioned Figure 7 56 7 7 Defining New Functions for Rule Node Conditions In Section 7 5 we saw how rule conditions could be defined using a combination of arithmetic operators and operands consisting of data attributes and values found in workitems and at the case level of process instances In Walkthrough D an example of a defined function was given isNotCompleted using the special variable this The Worklet Service provides a discrete class that enables developers to extend the availability of such defined functions That is a developer may define new functions that can then be used as or as part of composite conditional expressions in rule nodes That class is called RdrConditionFunctions the source code for the class can be found in the au edu qut yawl worklet support package Currently this class contains a small number of examples to give developers an indication of the kinds of things you can do with the class and how to create your own functions 7 7 DEFINING NEW FUNCTIONS FOR RULE NODE CONDITIONS 191 0009 Worklet Service Administration Tasks SP FC M BD a BD http locathost 8080 workletService wsAdminTasks sH 3774572081313148935 F Gs Cls Google ez Worklet Service Administration Tasks Title Case ID Task Type gt Equipment Lost in Transit 35 New Case Level External Exception Back View Details Completed YAWL is distributed under the LGPL Done
191. ing to role A or B e An org group can belong to another org group similarly to a role You may also set an Group Type for an org group via a dropdown select the type of group from the list then click the Save button e A position may report to another position allowing a lines of reporting hierarchy of positions to be created Again this is done in a similar fashion to setting a role belongs to hierarchy and the same cyclical constraints apply A position may also belong to an Org Group which can be chosen via the Org Group dropdown on the Positions tab page Figure 6 7 To enable easy backup and recovery of organisational data two tool buttons are provided on the top right of the tab panel They may be seen in detail in Figure 6 8 The button on the left is the Import Org Data from File button and the button in the centre is the Export Org Data to File button the third button refreshes the form in a similar way to the refresh button on other pages as mentioned previously To export your current set of org data click on the Export button a file called YAWLOrgDataBackup ybkp will be created and downloaded via your browser The file will contain your entire org database in XML format passwords are encrypted 6 3 ADMINISTRATION 129 nn Work Queues Edit Profile Team Queues Admin Queues Cases Users Services Logout p Positions Position Titles Reports To Assistant head of OD Head of CD z CD clerk
192. ing worklet then continue execution of the case In the same manner as the Selection Service the Exception Service also supports data mapping from a case to a compensatory worklet and back again For example if a certain variable has a value that prevents a case instance from continuing a worklet can be run as a compensation during which a new value can be assigned to the variable and that new value mapped back to the parent case so that it may continue execution The full capabilities of the Exception Service are better described in the walkthroughs in Section 7 6 But before we consider the walkthroughs we must first look at exactly how the rule sets are formed and how 156 CHAPTER 7 THE WORKLET SERVICE they operate and how to use the Worklet Rules Editor to manage rule sets for specifications These topics are discussed in the next section 7 5 Worklet Rule Sets and the Rules Editor This section describes the structure and operation of worklet rule sets A tool has been designed to manage the creation and modification of rule sets for specifications called the Worklet Rules Editor The structure and operation of rule sets is best described by using the Rules Editor to display and manipulate them So a description of how to use the Rules Editor is interspersed in this section with the description of the rule sets themselves Again the Worklet Selection and Exception Services work in very similar ways but with some necessary diff
193. ion isMotCompleted this Conclusion 1 suspend case 2 un worklet Cancel rder 3 remove ancestorlases Figure 7 53 Rule detail for Receive Reply the current worklet case back up the hierarchy to the original parent case that began the exception chain as opposed to allCases which refers to all currently executing cases of the same specification as the case which generates the exception So when the Cancel Order worklet completes the Send Reminder case and the original parent Timeout Test 3 are both cancelled by the Exception Service 7 6 WALKTHROUGH USING THE WORKLET SERVICE 189 F Rejecting a Worklet and or Raising a New External Exception The processes involved in rejecting a worklet launched either as a result of the Selection or the Exception Service and raising a new external exception that is an external exception which has not yet been defined formally an unexpected exception are virtually identical and so are discussed together in this section When the Worklet Service launches a worklet it selects the most appropriate one based on the current case context and the current rule set for the parent case As discussed previously in this chapter there may be occasions where the selected worklet does not best handle the current case s context perhaps because of a new business rule or a more efficient method of achieving the goal of a task being found In any event a worker may choose to reject the worklet t
194. ional events occurred and were added to the rule set Notice that at the bottom of the list the option to add a New External Exception is provided that option is explained in detail in Walkthrough F For this example lets assume the band has requested some refreshments for backstage Select that exception trigger and submit the form When that exception is selected the conclusion for that trigger s rule is invoked by the service as an exception handling process for the current case Go to the Work Queues form where it can be seen that the parent case has been suspended and the first workitem of the compensatory worklet Organise Refreshments has been enabled Figure 7 49 Organise Refreshments informs the staff member responsible to buy a certain number of bags of M amp Ms first workitem then to remove all the candies except those of a specified colour before delivering them to the venue mapped in from the parent case Once the worklet has completed the parent case is continued Item level external exceptions can be raised from the Work Queue page by selecting the relevant workitem 2If the two buttons don t appear the exception service has not been correctly enabled for the Resource Service review the installation section at the beginning of this chapter for details on how to enable the service 7 6 WALKTHROUGH USING THE WORKLET SERVICE 185 Loaded Specifications Change ToMid Venue Action taken if ticket sale
195. ith the Worklet approach thus providing very powerful flexibility support e YAWL s architecture is Service oriented and hence one can replace existing components with one s own or extend the environment with newly developed components e The YAWL environments supports the automated generation of forms This is particularly useful for rapid prototyping purposes e Tasks in YAWL can be mapped to human participants Web Services external applications or to Java classes e Through the C YAWL approach a theory has been developed for the configuration of YAWL models For more information on process configuration visit www processconfiguration com e Simulation support is offered through a link with the ProM www processmining org environment Through this environment it is also possible to conduct post execution analysis of YAWL processes e g in order to identify bottlenecks 1 2 Obtaining the Latest Version of YAWL As new versions of the YAWL Engine are released to the public they will be available for download at the YAWL Sourceforge website sourceforge net projects yawl From this site it is also possible to access the source code of all components for development purposes 1 3 The YAWL Foundation For up to the minute information on any aspect of the YAWL Initiative visit the YAWL Foundation Home page yawlfoundation org The YAWL Foundation is a non profit organisation that acts as custodian of all intellectual propert
196. ition to each task Every atomic task that requires work to be performed needs to have a decomposition A decomposition may be described as a contract between the task and its environment describing the data that will be assigned and updated when the task is performed and the so called YAWL Custom Service a web service designed for the YAWL environment that will be responsible for the task s execution Note that the YAWL Engine does not directly perform the work of the task responsibility is always deferred to the designated YAWL Service It is possible to define an atomic task without assigning it a decomposition they represent so called empty steps and are generally used to capture a point in the specification where there is a need to synchronise certain tasks and start a new set of tasks In our working example all tasks except one require a decomposition It is enough at this stage to simply create a decomposition per task To do this you need to right click on each task and select the Set Task Decomposition option For this example we ll choose the Default Engine Work list actually the worklist handler built in to the Resource Service as the type of decomposition This tells YAWL that when the task is ready to be executed it should be displayed in the default worklist Every instance of the task will then appear in the worklist of human participants so they may receive data relative to the task instance
197. k do itinerary segment within a single itinerary 5 5 ILLUSTRATIVE EXAMPLES 117 Multiple Composite Task do itinerary segment Instance Detail Bounds Queries Minimum Instances 1 Maximum Instances is infinite is equal to Continuation Threshold is infinite is equalto Instance Creation Static Dynamic B Multiple Composite Task do itinerary segment Instance Detail Bounds Queries Accessor Query f nake_trip legs Splitter Query for d in legs return d IH otal eternal ettattatetattettettettatatetatatatetatetatetatetatatatetetetatetatetatatatetatetatetatetatatatetatetatatatatatetatetatetatetatatatatatetetatatetatetatatetetatetatetatatatetatetatatatetatetatetatetatetatatatetetatetatetetatatatetetetatatetatetatetatatstetetetatetetetatatstetatetstetatetatetstetstetetetate Instance Query lt itinerarysSeqment gt do_itinerary segqment leg departure_location do_itinerary segment leg destination do_itinerary seqment startDate do_itinerary segment endDate do_itinerary segment flightDetails do_itinerary segment hotelDetails do_itinerary segment carDetails do_itinerary segment subTotal lt itinerarySeqment gt Aggregate Query for d in do_itinerary segment itinerarySegment return d Result Net Variable Figure 5 26 Instance details for task do itinerary segment 118 CHAPTER 5 HOW TO MANI
198. k on any other node rather than clicking on the Add Rule button doing that will immediately discard any input data values Don t click Cancel that closes the entire form without saving anything see below When you are done adding nodes click the Add Tree button to add the tree you have just created to the tree set selected via the selected Rule Type and Task Name lists IMPORTANT Once you have added the newly created tree to the selected tree set using the Add Tree button you will no longer be able to add nodes to the tree via the New Rule Set form This is to protect the integrity of the rule set Since each subsequent rule will be added because of an exceptional case or where the selected worklet does not fit the context of a case the preferred method is to create the base rule set and then add rules as they become necessary via the Add Rule form as described earlier In this way added rules are based on real case data and so are guaranteed to be valid In a similar vein there is no option to modify or delete a rule node within a tree once the tree has been added to the rule set since to allow it would destroy the integrity of the rule set because the validity of child rule nodes depend on the conditions of their parents When a tree is added to the tree set e If it is a case level tree the rule type that the tree represents will be removed from the Rule Type list That is the rule type now has a tree defined for
199. k waits until all incoming flows have either finished or will never finish OR Joins are smart they will only wait for something if it is necessary to wait However understanding models with OR joins can be tricky and therefore OR joins should be used sparingly A task with an AND Join will wait to receive completed work from Figure 3 3 Supported Splits and Joins in YAWL The one task in our example that does not need a decomposition is the one labelled Choose Approval Process This task does not need any participant interaction because the decision on whether to choose either Large Credit Approval or Small Credit Approval can be automatically determined with data made available to the workflow instance Congratulations you now have an executable YAWL workflow specification However more effort is needed with respect to data and resourcing to achieve real utility All YAWL can currently do with this specification is walk an unspecified user through a default path of the workflow 3 4 Advanced Workflow Concepts A specification capable of only walking a user through a path of a workflow is hardly going to win us any awards in workflow automation We still have at least two major concerns to address before our specification becomes useful Firstly we need to decide which participants should perform which tasks This is discussed in section 3 4 1 Secondly we need to figure out what data these participants need from the workfl
200. le will be split into individual task variable instances and how those instance variables are aggregated back into the MasterList on completion Figure 4 37 shows the Queries tab page for the Verify List MI task There are six parts to this dialog four requiring XQueries and two variable settings Multiple Instance Variable this specifies the task instance variable that has be defined to accept a single item from the net level list variable in our case the book variable Accessor Query this query defines the source of the data that needs to be split into multiple task instances in most cases as in our example it is a simple XPath expression specifying the net level variable that is being mapped into the MI task and exactly matches the input parameter set 76 CHAPTER 4 THE EDITOR aoe Update Parameters for Multiple Atomic Task Verify List Input Parameters XQuery Task Variable Create List_Builder MasterList book Update Remove Task Variables Name Type Usage book BookOrder Input amp Output Net Variables Name Type MasterList BookList Output Parameters XQuery Net Variable Create lt order gt Verify list book lt order gt MasterList Update Remove Figure 4 36 Update Parameter Mapping dialog for MI task Verify List for the variable in the Update Parameters dialog In this case it is List_Builder Masterlist note tha
201. lease select the Java tm Runtime to use sun 1 6 0 fusribinjava Figure 2 4 Select Java Version a If no Java version greater or equal 1 5 is found and the YAWL4Study for Windows installer is executed the supplied Java version will be installed A The installation will stop if no Java version greater or equal 1 5 is found Install the latest Java version before executing the YAWL installer The YAWL installer checks the usual installation paths like usr or usr local If you installed Java on your system but the YAWL installer is not able to find it create the following link user host ln s path to your java base dir usr local java Keep in mind that you need administration rights to generate the link Afterwards start the YAWL instal lation again 14 CHAPTER 2 INSTALLATION You are now ready to proceed with the installation When the installation completes you will see the Installation Completed page If you found a problem and could not complete the installation please post the problem to the sourceforge forum 2 3 YAWL4Enterprise The release package on the YAWL project web page on sourceforge provides an installation file for Windows In contrast to YAWL4Study YAWL4Enterprise allows the configuration of third party components like the application servlet container and the database server Preparation YAWL4Enterprise should be installed with an administrator account Installation is started by s
202. les Editor The selected folder contains a set of files in XML format that are essentially log files that capture the results of each selection process either via the Selection Service or through the selection of a compensating worklet via the Exception Service These files have an zws extension XML Worklet Selection These files are used by the Rules Editor to enable the addition of new rules for a specification e The worklets folder contains the worklet specification files These files are YAWL specifications that are run as required by the service Several of the folders contain examples 7 2 2 Configuring the Worklet Service Manual Installs Only The workletService war file should be located in the webapps directory of your Tomcat installation if necessary refer to Chapter 2 Section 2 5 for more information Then the file needs to be extracted to its own directory under webapps The easiest way to achieve this is to simply start Tomcat it will automatically extract install and start the Worklet Service Once the service is fully extracted and installed there are a couple of minor configuration tasks to complete 146 CHAPTER 7 THE WORKLET SERVICE Open the Worklet Service s web xml file in folder webapps workletService WEB INF in any text editor By default the worklet repository is located within the service s own file structures However you may change the location of the repository if you wish Locate the
203. log box will appear Retrieve the decomposition detail for the Enrol task 3 Click on the Create button An Update Task Variable dialog box will appear ORs Update Task Variable Extended Attributes Name StudentNumber Type string HH Usage Input amp Output HH Default Value Done Cancel Figure 4 28 Updating the Task Variable 4 Enter the Name of your variable choose the Type of the variable and its Usage from those listed click Done then Done again to exit the task decomposition detail dialog gt Enter StudentNumber for the name of the variable leave the type as string and set the Usage to Input amp Output Figure 4 28 Click Done Create another variable for the same task called SubjectCode with type string and usage of Input amp Output Click Done 5 The Enrol task now has two variables StudentNumber and SubjectCode Figure 4 29 68 CHAPTER 4 THE EDITOR e086 Update Task Decomposition Enrol Extended Attributes Task Decomposition Label Enrol Task Decomposition Variables Usage Create Input amp Output Input amp Output Update Remove YAWL Registered Service Detail YAWL Service Default Engine Worklist External Interaction C Automated Set Codelet Done Cancel 4 Figure 4 29 The Update Task Decomposition dialog for the Enrol
204. low Enabling the Worklet Exception Service When YAWL 2 0 is installed the Exception Service is configured as disabled in the YAWL Engine To enable the Exception Service a parameter has to be set in the YAWL Engine s web xml file Open the engine s web xml file in folder webapps yawl WEB INF Locate the parameter named Enable ExceptionService to enable the Exception Service change the param value to true see Figure 7 3 Save and close web xml The Exception Service uses extensions or hooks in the YAWL default worklist handler a component of the Resource Service to provide methods for interacting with the Worklet Service so if you have enabled the service in the Engine as above you also need to enable the extensions in the Resource Service To do so locate and open the Resource Service s web aml file in folder webapps resourceService WEB INFN Locate the context parameter named InterfaceX_BackEnd By default the entire parameter block is com mented out To enable the Exception Service extensions to the worklist simply remove the comment tags the lt and gt surrounding the context param block see Figure 7 4 below Save and close web sml fcatalina base is an environment variable pointing to the path of your Tomcat installation 7 2 INSTALLATION 147 lt PARAMS FOR EXCEPTION SERVICE gt lt context param gt lt param name gt EnableExceptionService lt param
205. lt xs element name Autor type xsirstring gt lt f KS i Sequence gt lt XS i ComplexType gt xS complexType name Booklist gt lt xe sequence maxOccurs 5 gt lt xs element name Book type Boo gt lt XS sequence gt lt xs complexType gt lt xs achema gt nn A F Invalid ln 19 col 40 sre resolve Cannot resolve the name Boo i Done Cancel 0 n Figure 4 22 When the data type definition is invalid dialog box Figure 4 26 4 5 4 Task Decomposition By choosing the Select Task Decomposition option when you right click on a task you have the ability to identify which decomposition is attached to the task A decomposition describes the variables handled by the task and the YAWL Service that will be responsible for performing the work the task represents at runtime Like nets tasks have decompositions where you can specify variables and a label to associate with the task Unlike nets which cannot share net decompositions there is a 1 N relationship between task decompositions scoped to the entire specification and their tasks scoped to nets meaning that a number of tasks within a specification may share the same decomposition Besides variables and a label task decompositions also allow the workflow designer to identify which web service the decomposition should invoke in a running workflow engine and whether the decomposition will create manual i e human acti
206. lues and submit it Once the order has been filled the process waits for payment to be received for the order before it is archived The Receive Payment task has an associated timer and so waits for some specified time to receive payment For the purposes of this example the wait time is set to 5 seconds Figure 7 51 186 CHAPTER 7 THE WORKLET SERVICE SEOKS Worklet Service Raise Case Level External Exception kas ma p CA x oo aa i PB http localhost 8080 workletService caseException caselD 22 es Cle Google ez amp Raise Case Level Exception Case ID Specification ID 22 OrganiseConcert Select the type of exception that has occurred Support Act Breakup Singer Tired and Emotional Guitarist Refused Visa Band Broken Up Ticket Sales Better than Expected ry Pam on Fam Band Requests Backstage Refreshments New External Exception ed Cancel Submit YAWL is distributed under the LGPL Figure 7 48 Raise Case Level Exception Screen Organise Concert example _ Accept Offer 22 BookStadiu 24 Buy_M_and_Ms_5 Accept amp Start Jul 10 2009 12 51 04 0 0003 21 Figure 7 49 Available Work Items after External Exception Raised While the deadline is reached the Engine notifies the Exception Service of the timeout event The timeout tree set is queried for the Receive Payment workitem There is a tree defined for the Receive Payment task wit
207. m jsp il b C o maer Cancel C Ok Figure 4 56 Custom form dialog See the YAWL technical manual for information regarding the creation and configuration of custom forms 4 13 Extended Attributes The Editor offers a means for defining extended attributes to be associated with task decompositions net variables and task variables Currently the implementation and the semantics of these attributes is left to the developer Extended attributes can be defined in property files which need to be placed in the folder lt editor_install_path gt YAWLEditorPlugins ExtendedAttributeProperties Attributes referring to net and task variables must be defined in a file named VariableProperties no exten sion while attributes referring to task decompositions must be defined in a file named DecompositionProp erties no extension The files are read at the Editor s next restart Attributes can be of type string boolean enumeration and XQuery The following is an example of a property file that defines the attributes description help mode refresh and skipSchemaValidation comments are indicated by a line starting with Decomposition Attributes Wed May 14 17 35 42 AET 2008 96 CHAPTER 4 THE EDITOR Done Cancel Figure 4 57 The dialog for editing the extended attributes associated to task decompositions description xquery help string mode enumeration normal final pending refresh xquery
208. mall Credit Approval task Anything more requires Large Credit Approval to be run The XPath expressions needed to capture this choice are shown in Figure 3 14 Once this is specified we are done We have a workflow specification that ensures the right work and data gets routed to the right participants at the right time AOO YAWLEditor Users adamsmj Documents research temp gs2 yawl 2 eS AIEEE m jeja Wla aa s mw al _ ru O f Simple Credit Application E ae Das 4 Task Icon No Icon f Manual padi erga Cac gt 4 Automated a Approval gt Routing Requirements 4 Plugin a Receive and Validate Approval Application Process aA eA Flow detail for Atomic Task Choose Approval Process all Credit Approval Target Task Predicate PP Large Credit Approval number Simple Credit Ap Small Credit Approval true Pa Predicate EOR Update Flow Predicate Net variable ApplicationID HH XPath Ex i gt v e x pression j Select a The bottom a _ __ number Simple Credit Application ApplicationAmount text gt 5000 cA Done Cancel Figure 3 14 XPath predicates to choose between flows of an XOR Split task 3 5 Where To From Here You ve now seen how we can construct a workflow specification for YAWL We ve used atomic tasks with various types of splits and joins along with resourcing and data requirements to impleme
209. mes enabled Because it is worklet enabled the Worklet Service is notified The Service checks to see if there is a set of rules associated with this workitem and if so the service checks out the workitem When this occurs the YAWL Engine marks the workitem as executing externally to the Engine and waits for the workitem to be checked back in In the meantime the Worklet Service uploads the relevant specification for the worklet chosen as a substitute for the workitem and launches a new case for the specification When the worklet case completes the Worklet Service is notified of the cases completion and the service then checks the original workitem back into the Engine allowing the original process to continue We have completed editing the Triage workitem and clicked the Complete button Go to the Work Queues page Instead of seeing the next workitem listed i e Treat we see that Test Fever the first workitem in the TreatFever process is listed in its place Figure 7 32 The TreatFever process has been chosen by the Worklet Service to replace the Treat workitem based on the data passed to the service Note that the case id for the Test Fever workitem is different to the case id of the parent process Worklets 7 6 WALKTHROUGH USING THE WORKLET SERVICE 175 Edit Work Item 1 2 Figure 7 31 Editing the Triage Workitem detail Offered 1 TreatFever Test Fewer Case Status Age Juls02 2009 13 04 10 0 00 00 0
210. mouse from the flow connector on the Input Condition to the one on the Atomic Task which will appear when the mouse hovers over 48 CHAPTER 4 THE EDITOR the edges of the task The editor will only show a connection point if it is valid to draw a flow connection between the objects The directed arc arrow between two objects is referred to as a flow Ormi Begin My Career Figure 4 5 An established flow relation relation or most often simply a flow it shows the flow of execution from one object in the net to the next That s it Your Atomic Task is set Repeat the process for the following Atomic Tasks in order Go to University Get A Job Career Started ra Link the Career Started task to the Output Condition the m symbol as per Figure 4 6 O FL mE Begin My Go to Get a Job Career Career University Started Figure 4 6 The My Career Net 7 Finally check the validity of specification by clicking on the Validate Specification button y in the Menu Toolbar or click on Specification in the Menu and choose Validate Specification If all things are going to plan then you should receive a confirmation saying that there were no errors detected Task Indicators Task indicators are mini icons that appear across the top of a task to provide a visual cue regarding settings that have been applied to the task An example of a task with all three available indicators is shown in Figure 4 7 Che
211. mpleted is slightly different since the parameter passed is the special variable this The this variable is essentially a WorkItemRecord that contains descriptors of the workitem the rule is testing enabling developers to write methods that test the values in the variable and act on those values accordingly If it is for a case level rule this contains the case data for the instance invoking the rule Both versions of this are passed as a string ified JDOM Element format See the YAWL source code for more details of the WorkItemRecord class if required What the execute methods sub block for the 7sNotCompleted function looks like is shown in Figure 7 60 The block gets this variable as a String from the args HashMap and then calls the actual isNotCompleted method see Figure 7 61 7 7 DEFINING NEW FUNCTIONS FOR RULE NODE CONDITIONS 193 if name equalsIgnoreCase isNotCompleted String taskInfo String args get this return isNotCompleted taskInfo Figure 7 60 Execute method s sub block for isNotCompleted function public static String isNotCompleted String itemInfo Element eItem JDOMConversionTools stringToElement itemInfo String status eItem getChildText status return String valueOf isFinishedStatus status Figure 7 61 Calling the actual isNotCompleted method Notice again that the function has been declared as private static and returns a String value The first line of the
212. ms Windows Linux and Mac OSX They have names similar to those shown in Table 2 1 a Windows YAWLA4Study_windows_2 0 exe Linux YAW L4Study_linux_2 0 bin MacOSX YAWLA4Study_osx_2 0 app zip Table 2 1 YAWLA4Study is available for three different operating systems Preparation YAWL4Study can be installed from an ordinary user account without administration rights as long as Java version 1 5 or greater is installed on the system a To start the installation simply double click on the installation file The installation file needs to have read and executable permissions Those can be assigned by right clicking the file selecting Properties and setting the appropriate permissions Alternatively the following shell command can be applied user host tmp chmod 755 YAWL4Study_linux_2 0_RC1 bin Afterwards start the installation by double clicking on the downloaded file or by invoking it from the com mand line user host tmp YAWL4Study_linux_2 0_RC1 bin Installation You will be greeted by a Welcome screen Pressing Nezt will take you to the License Agreement page shown in figure 2 2 The license agreement contains the Gnu Lesser General Public License Version 2 1 the Apache License Version 2 0 the BSD License and Sun s Binary Code License Agreement You need to accept the agreements to continue the installation 2 2 YAWL4STUDY 13 License Agreement v Please read the following License Agreement You must ac
213. n but not ReceiveSSN ssn text in the output parameter definition for task ReceiveSSN see Figure 5 12 This modified mapping is incorrect because it passes lt ssn gt some social security number lt ssn gt from task variable ssn to net variable ssn However the mapping has a valid syntax because both variables are strings and thus passes syntax validation in the YAWL Editor But at run time after the user submits his her social security number via task ReceiveSSN an bad process definition error page as shown in Figure 5 12 will appear indicating a failure has occurred validating the XQuery Also the executed credit rating process is halted 5 5 2 Example 2 Simple Make Trip Process This process provides a trip booking service When running this process the user is first asked to register for the trip The registration information includes customer name trip start date trip end date whether to include booking a flight hotel and or car and customer s payment account number After the registration the booking tasks may be executed in parallel according to the user s requirements and the booking details are also provided in each executed task After all the booking tasks complete the user is then asked to make payment for the trip and the process ends 108 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL YAWL 2 0 Worklist Jaya User Mozilla Firefox SEE File Edit View History Bookmarks Tools Help
214. n and badly formed ones will be red Again red text will be accompanied by a split pane table returning the parse errors that cause the text to be badly formed For workflow designer convenience two XQuery buttons are supplied to automatically generate XQuery expressions from available net variables The add XQuery of element s content button will return just the content of the XML element for this variable which is useful for simple value transfer between two variables of the same XML Schema type and is expected will be the button used in most cases The other button add XQuery of entire element will return the entire XML element of the selected variable which is useful for times when you want to create a complex type expression from individual variable elements Experience with XMLSchema and XQuery are necessary to understand the effects this button will have on runtime YAWL engine state TO CHAPTER 4 THE EDITOR ra Select the StudentNumber variable from the list of Existing Task Variables Select the Student Number net variable then click add XQuery of element s content Figure 4 31 Click Done Create another Task Parameter and map the net SubjectCode to the task variable of the same name using this technique Click Done and Done again 8 Oe Update Task Parameter StudentNumber from element of net variable StudentNumber HA XQuery lt StudentNumber gt 7 Attend University StudentNumber text
215. n Reallocate Stateful When granted allows a participant to transfer responsibility for the execution of a work item from themselves to another participant with the data parameters of the work item having their current values maintained e Can Deallocate When granted allows a participant to reject or rollback the allocation of a work item to their allocated queue The work item is redistributed using the original resourcing specification but with the participant removed from the distribution set e Can Delegate When granted allows a participant to delegate the responsibility for the execution of a work item to a subordinate member of their work team as defined by the organisational model 132 CHAPTER 6 THE RUNTIME ENVIRONMENT 609A Manage Resourcing Wizard for Atomic Task Approve Step 5 Establish Default User Runtime Privileges for this Task Can a participant suspend a started work item of this task Can a participant reallocate a work item of this task to another participant resetting state Can a participant reallocate a work item of this task to another participant retaining state Can a participant deallocate themselves from a work item of this task Can a participant delegate a work item of this task to another participant Can a participant skip a work item of this task lt Back gt Next Figure 6 10 Step 5 of the resource management wizard e Can Skip When granted allows a participant t
216. n from the members of the distribution set defined earlier will actually be allocated the work item The currently available mechanisms are e Round Robin by time chooses the participant in the set who has not been allocated a task instance for the longest time e Round Robin by least frequency chooses the participant in the set who has been allocated this task instance the least number of times in the past e Round Robin by experience chooses the participant in the set who has been allocated this task instance the most number of times in the past e Random Choice randomly chooses a participant from the set the default and 4 11 TASK TIMER 91 8608 Manage Resourcing Wizard for Atomic Task Approve Step 3 Specify Distribution Set Filter s Filters Tick those filters to be applied to the specified distribution set Set parameter values for the selected filter as required Filter Parameter Value Filter bv Organisational Data Runtime Constraints _ Allow this task to be piled to a single participant Choose participant s who completed previous task register_name_7 j M Do not choose participant s who completed previous task Check2_5 lt Back gt Next Finish Figure 4 51 Step 3 of the resource management wizard e Shortest Queue chooses the participant in the set who has the least number of task instance currently in their work queue Step 5 In Step 5 shown in Figur
217. n pick up an error which the other approach cannot By choosing Configure Specification Analysis under the Tools menu in the Editor one can choose what type of verification the YAWL editor needs to perform As some forms of verification may require quite a bit of time it is important to choose the right approach and generally speaking it is probably best not to verify every intermediate version of a specification The screen shot shown in Figure 4 45 shows the options one can choose for the analysis based on Reset nets This form of analysis supports the use of reduction rules YAWL reduction rules can be applied to the net and Reset net reduction rules can be applied to the Reset net that results from the mapping of a YAWL net The application of these reduction strategies may significantly reduce the workflow that needs to be analysed hence it may significantly reduce the time that verification takes Note that there is overhead associated with performing the reductions themselves Also worth mentioning is that the soundness check is supported for workflows with a finite state space The editor caps the state space at a certain number of states and tries to construct the reachability graph for the workflow If the upper bound is not exceeded the soundness of the workflow can be determined with certainty The wofYAWL analysis tab page of the Configure Specification analysis dialog is shown in Figure 4 46 The reader is referred to 21
218. n_Treat cws xws for Xml Worklet Selection The identifiers in each part of the filename refer to the parent specification instance not the worklet case instance Also the WorkItemID identifier will not appear for case level rule types So to add a new rule after an inappropriate worklet choice the particular selected log file for the case that was the catalyst for the rule addition must be located and loaded into the Rules Editor From the Add Rule screen click the Open button to load the selection information from the relevant selected log file The File Open dialog that displays will open in the selected folder of the repository Select the appropriate file for the case in question then click OK Note that the selected file chosen must be for an instance of the specification that matches the specification rule set loaded on the main screen in other words you cant attempt to add a new rule to a rule set that has no relation to the zws file opened here If the specifications dont match an error message will display Figure 7 17 shows the Add Rule form with the selected file 12_ Casualty Treatment_Selection_Treat cws loaded The Cornerstone Case panel shows the case data that existed for the creation of the original rule that resulted in the selection The Current Case panel shows the case data for the current case that is the case that is the catalyst for the addition of the new rule The New Rule Node panel is where the details of the
219. ncluding the launching of the worklet SendReminder The SendReminder worklet consists of two tasks Send Request and timer enabled Receive Reply again for the purposes of the example this task waits for 5 seconds before timing out When the task times out the Exception Service is notified There is a single timeout rule for the Receive Reply task its condition is again isNotCompleted this but this time the rules conclusion looks like this File Cancellation is the first task of the Cancel Order worklet What we now have is a hierarchy of worklets case Timeout Test3 is suspended pending completion of worklet case Send Reminder which itself is sus pended pending completion of worklet case Cancel Order Worklets can invoke child worklets to any depth Notice the third part of the handling process remove ancestorCases Ancestor Cases are all cases from 188 CHAPTER 7 THE WORKLET SERVICE E Worklet Rules Editor lt Browse gt TimeoutTest3 File Rule Gptions Help zQ Bl Rule Tupe TimeClut Task Name Receive Payment ROR Tree Comerstone Case Rule 0 Cost 200 f Rule 1 Paid False Selected Node Hode ID i Parent Mode ID E Condition lisMotCompleted this Conclusion 1 suspend workitem 2 tun worklet SendAeminder 3 complete warkitem Description No payment received after timeout Figure 7 52 Rules Editor Showing Single Timeout Rule for Receive_Payment Task Condit
220. nd runs it waiting for it to complete and returning the result if any via an output parameter To associate a codelet with a task decomposition first mark the decomposition as automated by ticking the Automated checkbox in the Task Decomposition dialog see Figure 4 29 When checked the Set Codelet button is enabled clicking that button opens the Set Codelet for Automated Decomposition dialog listing the available codelets Figure 4 48 Note that a valid connection to the Resource Service is required for this list to be populated with codelets The dialog lists the available codelets together with a description of what each one does and the task variables required to successfully execute it For example if ExampleCodelet is chosen the automated task requires 3 variables to be created input parameters a and b and output variable c all of type long These parameters must be added to the task in the normal manner at runtime if the required variables are not present the codelet will be unable to successfully complete the task will still complete successfully however The codelet repository has been designed as pluggable so that designers and developers can easily add new codelets to perform various operations which will immediately be available to process designers via the dialog above as long as there is a valid connection to the Resource Service 88 CHAPTER 4 THE EDITOR oo Set Codelet for Autom
221. nd so needs a servlet container installed to host them We recommend Apache Tomcat be used it if free stable and fully tested as a YAWL host over a number of years YAWL requires Tomcat version 5 5 26 or later The first step is to download the latest Tomcat version from tomcat apache org The simplest way to install Tomcat in a Windows environment is to use the purpose built Windows installer provided http sourceforge net projects yawl 2 5 MANUAL INSTALLATION Machine Devices Help Welcome To I i Built using Knoppix Technology SL comes with ABSOLUTELY NO WARRANTY permitted by applicable law to the extent INIT version 2 78 knoppix booting Autoconfiguring devices I pE egistering unionfs 1 0 14 INIT Entering runlevel 5 Start Tomcat Jsing CATALINA_BASE usr local tomcat sing CATALINA_HOME usr local tomcat Jsing CATALINA_TMPDIR usr local tomcat temp sing JRE_HOME usr local java isuCpam_unix 385 session opened for user dsl by uid 0 QOH Right Ctrl Figure 2 11 YAWLive Bootphase Machine Devices Help D Eile Edit View Go Bookmarks Tools Help rte YAWL Editor YAWL Control Centre Y4WLEditor ramdisk home dsl ordertulfilment yawl Net Edit Elements Tools View Specification Help c Task Icon No Icon o 6 Manual o o Routing Plugin Purchagg Order Join Split _ Contirm Puchase Order Order Tiel P
222. nerated work Should all atomic tasks in the net be unlabelled This message appears if none of your atomic tasks are associated with a decomposition To add a decom position to a task and thus ensure that the engine will get a user to handle the task at this point in the workflow right click on the task and choose Select Task Decomposition Choose Create and in the following window Update Task Decomposition and enter the name of your task under Decomposition Label then click Done My specification won t validate without any errors and I don t know what to do First check the logic of your specification and exercise every branch of your workflow for correctness If you are sure of your workflow consult the YAWL website for the proper use of the YAWL elements http yawlfoundation org How do I find out more about the elements and principles of the YAWL workflow specifications For more information about the mechanics of the YAWL workflow elements please consult the YAWL website http yawlfoundation org 98 CHAPTER 4 THE EDITOR Chapter 5 How to Manipulate Data in YAWL 5 1 Introduction Compared to most of the existing workflow management systems which use a propriety language for dealing with data YAWL completely relies on XML based standards like XPath and XQuery for data manipulation This document provides some insights into data manipulation in YAWL in terms of data visibility defining data
223. new rule may be added Notice that the ids of the parent node and the new node are shown as read only the Rules Editor takes care of where in the rule tree the new rule node is to be placed and whether it is to be added as a true child or false child node IMPORTANT Since we have the case data for the original rule and the case data for the new rule to define a condition for the new rule it is only necessary to determine what it is about the current case that makes it require the new rule to be added That is it is only where the case data items differ that distinguish 7 0 WORKLET RULE SETS AND THE RULES EDITOR 163 one case from the other and further only a subset of that differing data is relevant to the reason why the original selection was inappropriate For example there are many data items that differ between the two case data sets shown in Figure 7 17 such as PatientID Name Sex Blood Pressure readings Height Weight and Age However the only differing data item of relevance here is HeartRate that is the only data item that in this case makes the selection of the TreatRash worklet inappropriate on Add New Rule 127_CasualtyTreatment_Selection_Treat m Rule Type Selection Task Mame Treat Comerstone Case Current Case PatientID 345 768 Pn FatientlD 98769067 a Sex fl Sex F DiastolicBP 80 DiastolicBP 110 Height 1 8 Height 1 57 HeartRate 72 Hearth ate 190 Eel SystolicBP 120 J
224. nges to the Data Values BookStadium SellTickets DoShow Figure 7 42 The OrganiseConcert Specification there are no pre case constraint rules defined so the notification is simply ignored Tip To follow what is happening watch the log output in the Tomcat command window or the contents of the log file catalina out in Tomcat s logs folder both the exception and selection services log all interactions between themselves and the Engine to the Tomcat window and to a log file found in the logs folder of your Tomcat installation See Appendix 7 8 of this manual for a sample log output for this walkthrough Pre case constraints can be used amongst other things to ensure case data is valid or within certain ranges before the case proceeds can be used to run compensatory worklets to correct any invalid data or may even be used to cancel the case as soon as it starts in certain circumstances As a trivial example of the last point launch an instance of the Casualty Treatment specification discussed in Walkthrough A and enter smith for the patient name when the case starts The Casualty Treatment rule set contains a pre case 182 CHAPTER 7 THE WORKLET SERVICE constraint rule to cancel the case if the patient s name is smith presumably smith is a hypochondriac This also serves as an example of exception rules and selection rules being defined within the same rule set Directly following the pre case event the Engine n
225. nstances and Maximum Instances Static mode means the number of task instances started cannot vary once the task is activated Dy namic mode means the same number of task instances as static mode are started initially but new instances of the task may be started dynamically at runtime i e after task execution has begun up to the value entered in Maximum Instances 4 3 CREATING YOUR FIRST SPECIFICATION 59 amp O O Multiple Atomic Task Do Private Study Instance Detail Minimum Instances 5 Maximum Instances is infinite is equal to Continuation Threshold is infinite is equal to Instance Creation Static Dynamic Done Bounds Queries 100 we Figure 4 12 Instance Bounds on Multiple Instance Tasks Set the Instance Creation type to Static 5 Set the Minimum Instances value This is the minimum number of instances of this task that will be started when the task is activated Set the Minimum Instances to 5 6 Set the Maximum Instances value This is the maximum number of instances of this task that can be created from this task Set the Maximum Instances to 100 7 Set the Continuation Threshold value The moment all task instances created have completed or if the number of instance created exceeds the Continuation Threshold the number specified for the Continu ation Threshold have completed the multiple instance task itself will be con
226. nt Each work item on a started queue has begun execution in a system sense but may or may not have had any actual work begun for it by the participant such work is performed by the participant viewing editing and finally completing the work item C rane earne anaes rannas com usos oosa sees J woa gt rr Work Items Specification Task View Edit 49 1 Create_Book_List_4 Order Fulfilment ywl Greate Purchase Order 50 1 Assess_affected_area_3 52 1 1 Create_Purchase_Order_104 3 1 Assess affected area 3 ae Case Status Reallocate s l 52 1 1 Executing Reallocate s f sia a Jul 23 2009 15 22 11 0 00 15 19 Figure 6 14 The Started Work Queue A participant may take the following actions on a work item in an started queue e View Edit This action will display the data parameters and their current values for the selected work item either on a dynamically generated form see Figure 6 15 or if specified a custom form allowing the participant to view and or edit the form s values Any modified values are stored so that this action can be repeated for a particular work item a number of times before completion allowing 136 CHAPTER 6 THE RUNTIME ENVIRONMENT Edit Work Item 53 1 register conte Figure 6 15 An Example of a Dynamically Generated Form the work item to be processed by the participant in a progressive manner if required This action is disabled if the work item has no dat
227. nt a simple credit application processing workflow specification But we have so far only scratched the surface of what can be achieved with YAWL What you haven t seen yet is how larger workflows can be constructed by binding a number of nets together with composite tasks We are also capable of iterating through a number of instances of a single task using Multiple Instance Task constructs A single task can also be used to trigger the cancellation of current work in other parts of the workflow which might be used for modelling a customer calling and cancelling an order that is currently being processed Finally we haven t described conditions which represent the state a workflow is in after one task is finished but before another starts Conditions allow us to model two or more participants competing for the same work or a user making a decision on things that workflow systems 3 5 WHERE TO FROM HERE 37 cannot not automatically determine An example of this would be asking a participant to decide on whether the aesthetics of some partially assembled work are appealing or not and having the workflow coordinate further work based on that choice What we ve also glossed over here is how to actually use YAWL s toolset We have used version 2 0 of the Editor and of the Engine for the screenshots in this chapter The components of YAWL can all be found at Sourceforge via the URL http sourceforge net projects yawl Further explanations
228. ntly open in the Editor displays the New Rule form to allow the addition of new tree sets to the opened rule set file for rule types that have not yet been defined for that specification See the Creating a New Rule Set and or Tree Set section below for more details Open Rules File Opens an existing rules file for browsing and or editing The title bar shows the name of the specification associated with the currently loaded rule set Close Rules File Closes the currently opened rules file Only one rules file may be open at any one time Add New Rule Node Displays the Add Rule form to allow the addition of a new rule node to an existing tree to refine a worklet selection See the section below on the Adding a New Rule for more details Tree Viewer Displays the Tree Viewer form which provides the ability to view large trees in full screen mode Config Form Displays the configuration form discussed above About Box Displays some information about the rules editor version number date and so on Other Features Current Rule Type This drop down list displays each rule type that has a tree set defined in the opened rules file Selecting a rule type from the list displays in the Tree View an associated rules tree from the tree set Works in conjunction with the Task Name drop down list Current Task Name This drop down list displays the name of each task that has a rules tree associated with it for the rule type selected in
229. o a smaller venue change the values to match those in Figure 7 46 then complete the workitem The third workitem in the worklet Tell Punters is designed for the marketing department to advise fans and existing ticket holders of the change in venue Start the workitem Notice that the values here are read only since this item is meant to be a notification only the person assigned does not need to change any values This is the last workitem in the worklet so when that is completed the engine completes the case and notifies the Exception Service of the completion at which time the service completes the third and final part of the exception handling process i e continuing or unsuspending the Do Show workitem so that the parent case can continue Back at the Work Queues page the Do Show workitem is now shown as enabled and thus is able to be started Check it out now and notice that the data values entered in the worklet s Book Ent Centre workitem have been mapped back to the parent case D Exception External Trigger Example It has been stated that every case instance involves some deviation from the standard process model Some times events occur completely removed from the actual process model itself but affect the way the process 184 CHAPTER 7 THE WORKLET SERVICE Edit Work Item 9 2 Figure 7 46 The Book Ent Centre Workitem detail instance proceeds Typically these kinds of events are handled off system
230. o have the execution of a work item skipped that is immediately completed without performing its work e Can Pile When granted allows a participant to demand that all future instances of work items derived from this task in all future instances of the specification of which the task is a member are immediately directly routed to the participant and started All task privileges are denied by default and so must be set explicitly for each task as required 6 4 Work Queues Work items have an associated life cycle and when interacting with the Resource Service it is important to understand the various stages that a work item can go through An overview not complete but sufficient for our purposes of the life cycle of a work item is shown in Figure 6 11 The labels of the arcs correspond to the names of buttons that users of the Resource Service can click on to effect the state change Each participant has access to their own work queues which are collectively known as a worklist a graphical representation of their work queues via a series of web forms Each worklist consists of four work queues Offered Allocated Started and Suspended Depending on a participant s privileges there are a number of actions that can be performed on a work item in each queue Some are concerned with processing the work item while others provide for changes to the work item s resourcing The layout of each work queue is similar see for example Fig
231. o the third Verify List workitem is checked back into the Engine by the Worklet Service the Engine determines that all the child items of the Verify List workitem has completed and so the original process continues to its final workitem Show List Start and edit the Show List workitem to show the changes made in each of the Get_Bob worklets have been mapped back to the original case Figure 7 41 C Exception Constraints Example This walkthrough uses a specification called OrganiseConcert to demonstrate a few features of the Worklet Exception Service The OrganiseConcert specification is a very simple process modelling the planning and execution of a rock concert Figure 7 42 shows the specification as it appears in the YAWL Editor First ensure the Exception Service is enabled see Section 7 1 3 for details Navigate to the YAWL Case Mgt page and upload the OrganiseConcert specification from the worklets folder of the worklet repository Then launch an OrganiseConcert case As soon as the Engine launches the case it notifies the Exception Service via a PreCaseConstraint event If the rule set for OrganiseConcert contains a rule tree for pre case constraints that tree will be queried using the initial case data to determine whether there are any pre constraints not met by the case In this example 7 6 WALKTHROUGH USING THE WORKLET SERVICE 181 Edit Work Item 3 5 UserList Figure 7 41 The Show List Workitem Showing the Cha
232. od receives as arguments the name of the function to execute and a HashMap containing the functions parameters all are passed as String values 192 CHAPTER 7 THE WORKLET SERVICE public static String max int x int y if x gt y return String valueOf x else return String valueOf y Figure 7 57 Max function public static final String _functionNames max min isNotCompleted today Figure 7 58 Adding the name else if name equalsIgnoreCase max int x getArgAsInt args x int y getArgAsInt args y return max x y Figure 7 59 Execute method for the max function The execute method is essentially an if else if block the sub blocks of which call the actual functions defined The section of the execute method for the maz function is shown in Figure 7 59 The first line checks to see if the name of the function passed to the execute method is max If it is the parameters passed with the function as String values in the HashMap args are converted to integer values and finally the maz function is called its return value is passed back from the execute method to the calling Worklet Service The getArgsAsInt method called in the snippet above is defined in the Implementation section of the class s code It is here that you can create private methods that carry out the external work of the any functions defined as required The definition of 2sNotCo
233. on that triggered the exception Because the service allows you to define exception handlers for all exception events and even to add new handlers at runtime all exception events are able to be captured on system so that the handlers are available to all future occurrences of a particular event for the same context And since the handlers are worklets the original parent process model only needs to contain the actual business logic for the process 7 4 USING THE WORKLET EXCEPTION SERVICE 153 while the repertoire of handlers grows as new exceptions arise or different ways of handling exceptions are formulated IMPORTANT While the Selection Service is linked explicitly to tasks as defined in the YAWL Editor and thus available whenever a worklet enabled task is executed the Exception Service is either enabled or disabled on or off when it is enabled it manages exception handling for all process instances executed by the engine explicitly linking a task or process to the service is not required Also the Selection and Exception Services can be used in combination within particular case instances to achieve dynamic flexibility and exception handling simultaneously 7 4 1 Exception Types This section introduces the ten different types of exception that have been identified eight of which are supported by this version of the Worklet Service Some are related while others are more distinct Later sections will sh
234. on gt lt ruleNode gt lt ruleNode gt lt id gt i lt id gt parent O lt parent gt lt truechild gt 6 lt trueCchild gt lt falsechild22 lt falseCchild gt lt condition gt Fever true lt condition gt lt cone lusion gt lt 1 gt lt action gt select lt action gt lt target gt TreatFever lt target gt af 1 gt lt cone lusion gt Cor ieretone Figure 7 11 Excerpt of Rule Set file Casualty_Treatment xrs added later if required as could any of the other types not yet defined in the rule set Referring back to Figure 7 11 notice that the file specifies a Selection rule tree for the Treat task The second ruleNode contains a condition Fever True and a conclusion of TreatFever Thus when the condition Fever True evaluates to true the worklet TreatFever is chosen as a substitute for the Treat task Notice also that each rule node except the first has a parent and may have two child nodes a true child and a false child To summarise the hierarchy of a rule set from the bottom up e Rule Node contains the details condition conclusion id parent and so on of one discrete ripple down rule e Rule Tree consists of a number of rule nodes in a binary tree structure e Tree Set a set of one or more rule trees Each tree set is specific to a particular rule type timeout selection etc The tree set of a case level exception rule type will contain exactly one tree The tree set
235. on process step 3 Action continue Target workitem Successful work item unsuspend 20 DoShow_4 HANDLE CHECK WORKITEM CONSTRAINT EVENT Checking post constraints fo workitem 21 3 Tell_Punters_4 No post task constraints defined fortask Tell_Punters Exception monitoring complete for case 21 HANDLE CHECK CASE CONSTRAINT EVENT Checking constraints for end of case 20 No post case constraints defined for spec OrganiseConcert HANDLE CHECK WORKITEM CONSTRAINT EVENT Checking post constraints for workitem 20 3 DoShow_4 No post task constraints defined for task DoShow Exception monitoring complete for case 20 196 CHAPTER 7 THE WORKLET SERVICE Chapter 8 Other Services Because of the open design of the YAWL interfaces it is possible to design a YAWL Custom Service to perform the work of a task instance using a wide variety of techniques to meet particular needs Previous chapters have described the Resource and Worklet Services which while quite complex are examples of the sorts of things that can be achieved using Custom Services This chapter briefly describes a few other custom services their varied purposes and their use Please consult the YAWL Technical Manual for detailed information on the development of YAWL Custom Services 8 1 Web Service Invoker Service The Web Service Invoker Service WSInvoker provides a mediation layer between the Engine and external SOAP web services In this way a task can be associated to
236. onding net parameter For a task output parameter the matching net parameter needs an expression to retrieve the value of the task parameter Figure 3 13 shows an example of the queries needed for the Determine Credit Requirements task note that XPath expressions of this kind are generated with a couple of mouse clicks in the Editor A similar exercise can then be conducted for the parameters of the remaining tasks The only thing remaining to do with data in our specification is to deal with the XOR Split XOR splits need a boolean XPath expression to be associated with each outgoing flow of the split These expressions are evaluated once a task instance completes Thus the expressions can only interrogate the state of a net that a recently completed task has updated Expressions that evaluate to true indicate that a flow is to be taken In the case of an XOR Split the flows have an ordered priority specified The first flow in order whose XPath expression evaluates to true will be the only flow taken from a completed task The only task we need to consider in this regard is Choose approval process Consulting our transcript again 5Each XOR split and OR split has one flow specified as the default and is assumed to always have true value to ensure that the workflow can continue even when all other flow conditions evaluate to false 36 CHAPTER 3 GETTING STARTED WITH YAWL approval amounts of less than 5000 are to be routed to the S
237. oned or automated non human actioned tasks When two tasks share the same decomposition we are saying that the same activity is required in two different places in the workflow 4 5 ADDITIONAL SPECIFICATION FEATURES 65 e00 Update Net Variable Extended Attributes Name testGeek Type Geek ss Initial Value lt Mame gt John Frank lt Name gt lt Salary 10000 00 lt Salary gt Done Cancel Figure 4 23 A Geek net variable with a valid initial value Update Net Decomposition Attend_University Net Decomposition Label iscir MES Net Decomposition Variables Name Type Usage Create A Update Remove Done Cancel Le Figure 4 24 Updating Attend University Net Variables the two tasks may be named the same or differently but they will share the same underlying definition of work From the Select Task Decomposition dialog you can use the drop down list to select an existing decomposi tion or alternately you can click the Create button to generate a new one that will become the task s decomposition Figure 4 27 4 5 5 Task Decomposition Detail Task Variables You can add variables to a task to store specific information relating to that task in a similar way to adding variables to a net Task variables have several uses One use is for transferring information between workflow users and the wo
238. opriate choice for the current case So when a new rule is added you are given the 166 CHAPTER 7 THE WORKLET SERVICE choice of replacing the executing inappropriate worklet instance with an instance of the worklet defined in the new rule After the Save button is clicked a message similar to the Figure 7 21 is shown providing the option to replace the executing worklet using the new rule The message also lists the specification and case ids of the original work item and the name and case id of the running worklet instance Replace running worklet Do you wish to immediately replace the running Worklet case For Workikem 12 3 3 Treat using the new rule Workitem Spec ID Casualty Treatment Workitem Case ID 12 3 Workitem Task ID Treat Running Worklet TreatFever Wiorklet Case ID 13 Figure 7 21 Message Dialog Offering to Replace the Running Worklet If the Yes button is clicked then in addition to adding the new rule to the rule set the Rules Editor will contact the Worklet Service and request the change For this process to succeed the following must apply e Tomcat is currently running and the Worklet Service is correctly installed e The Service URI specified in the Rules Editor configuration dialog is valid and e The worklet originally chosen is currently running A message dialog will be shown soon after with the results of the replacement process sent from the Worklet Service back to the Rules Editor
239. opular gadgets to choose for your page you must be connected to the internet to access an iGoogle gadget To load the YAWL Worklist gadget 1 Click the Add feed or gadget link on the bottom of the list of links on the left frame of the page under Sort By and Narrow by Category link lists 2 In the input box that appears Figure 6 19 enter the URL http www yawlfoundation org gadgets igYWorklist xml 3 Click the Add button 4 Click OK on the warning dialog that appears Add feed or gadget Type or paste the URL below a yawlfoundation org gadgets igyWo rklisk xml Add 5 Information for Feed owners Developers Figure 6 19 Adding the Worklist Gadget to an iGoogle Page When you go back to the iGoogle home page the YAWL Worklist should appear Figure 6 20 but before it can be used some settings must be entered for it e UserID required A valid YAWL user account id e Password required The password for the nominated YAWL account Note that the password is retained as plain text so please ensure you log out of iGoogle before anyone else uses the same computer e YAWL Base URI required The URI of the Tomcat container running the YAWL Resource Service that will recognise the userid and password entered The YAWL URI may be local on the current computer or remote accessible via the internet e Name optional Any text entered here will display on the titlebar of th
240. or the make trip net 114 CHAPTER 5 HOW TO MANIPULATE DATA IN YAWL Update Het Decomposition make trip Het Decomposition Label make trip Het Decomposition Variables Name Usage customer String Local itinerary utput nly eqs utput Only atartDate utput Only Qutput Only lightDetails Local hotelDetails Local Figure 5 22 Net variable definitions for the make trip net A Update Parameters for Atomic Task register Input Parameters E z Het Variables Task Variables Mame customer string itinerary startDate endDate flightDetails hotelDetails carDetails payAcctumber subTotal Output Parameters AALE Met Variable register customer texti Customer register legs register pay ccNumber textl payiccNumber A 3 Figure 5 23 Parameter definition for task register 5 5 ILLUSTRATIVE EXAMPLES B Update Parameters for Atomic Task pay Input Parameters ZALE Task Variable ieee triprcustomer texti customer enake Vere nid eal yes eee ey tm itinerary sum Make tCrip itinerary itineraryoeqment subTotal make trip payaccNumber textt pay accNumber Net Variables Mame customer itinerary legs atartDate endDate Elightbhetails hotelDetails carDetails payaccNumber aubTotal Type Usage String Local P ka Output Parameters Task Variables Mame customer itinerary i string Input Only payA
241. ordinator that manages the execution of codelets for automated tasks ASIDE The Resource Service provides functionality to support the identified resource patterns 17 and associated activities However as a custom service it is completely removed from the operation of the Engine This means that developers are free to develop other custom services that communicate directly with the Engine and thus bypassing the Resource Service although support for the resource perspective would also be lost Alternately the Resource Service provides a number of interfaces expose the full functionality of the service which developers may exploit to override service components For example other types of worklist services may be developed that leverage the resource management capabilities of the Resource Service but present work to users in different or novel ways external organisational data sources may be used in place of the default internal data model supported by the Resource Service Custom Forms may be defined to lFor a discussion of how the workflow resource patterns have been realised in newYAWL see appendix A 3 starting on page 373 of 20 121 122 CHAPTER 6 THE RUNTIME ENVIRONMENT display work item data rather than using the default dynamically generated forms and so on Also the Resource Service is extendible in many ways for example developers may add new allocation strategies filters constraints codelets etc at any
242. osition For example in Figure 6 18 the participant listed holds the position CD clerk which reports to the position of the currently logged on participant Head of CD e A participant who has been granted the user privilege View All Work Items of Org Group may view a list of all the active work items that appear on the work queues of all the participants that are members of the same Org Group as the logged on participant All of the information displayed on this screen is read only A participant who has been granted both privileges may switch between views using the radio buttons to the right of the form if they have been granted one of the two privileges the other choice is disabled 6 7 YAWL Worklist iGoogle Gadget A simplified version of the YAWL worklist is offered as an iGoogle Gadget so that users can see the workitems currently in their work queues as a live feed along with the information in the other gadgets they may have 6 7 YAWL WORKLIST IGOOGLE GADGET 139 enabled on their iGoogle page 6 7 1 Setting up the Worklist Gadget The first step in setting up the gadget is to create a personal iGoogle page To do so browse to Google then click the Google link in the top right corner of the page If you have not yet done so you will be asked to create an account When you have your iGoogle page loaded click on the Add Stuff link on the right of the page header You will see a page with a list of p
243. ote you cannot create flows arrows between tasks while using the Marquee Selector Drag Net Window l Select this button to drag the visible window of a net around that net 4 2 4 Other Components The Canvas The Canvas is where elements are placed to create and modify a workflow specification Task Icons Panel This panel shows a set of icons that can be selected and placed on the tasks of your specification to add visual cues to aid in the understanding of your models by others The Editor comes with a standard set of icons and you may also provide your own icons and access them via this panel Note that the icons are grouped for ease of use only you are not limited in how you actually use the icons in your model Decorations Panel The Decorations panel provides a set if decorator types that may be attached to a task You can select the type of decorator what edge it is to be positioned on the task and choose a colour to use for each decoration Notes and Problem Panel This panel consists of two tabs e On the Notes pane you can add freeform text to accompany the selected task or condition e The Problems pane will list problems or messages that may occur while you are building your model when you validate it or when you analyse it Status Bar The Status Bar consists of three parts 46 CHAPTER 4 THE EDITOR e On the left are two icons that indicate whether there are currently valid connections to the Engine
244. otifies the Service of a PreltemConstraint for the first workitem in the case in this case Book Stadium The pre item constraint event occurs immediately the workitem becomes enabled i e ready to be checked out or executed Like pre case constraint rules pre item rules can be used to ensure workitems have valid data before they are executed The entire set of case data is made available to the Exception Service thus the values of any case variables may be queried in the ripple down rules for any exception type rule While there are pre item constraint rule trees defined in the rule set there are none for the Book Stadium task so this event is also ignored by the service The Book Stadium workitem may be started in the normal fashion This workitem captures the seating capacity cost and location of the proposed rock concert These may be changed to any valid values but for the purposes of this example just accept the default values as given Figure 7 43 Edit Work Item 8 1 ANZ Stadium Cancel Save Complete Figure 7 43 The Book Stadium Workitem detail When the workitem is submitted a PostItemConstraint event is generated for it by the Engine There are no post item constraint rules for this workitem so again the event is just ignored Then a pre item constraint notification is received for the next workitem Sell Tickets This workitem records the number of tickets sold and the price of each ticket Enter a price o
245. ou take on the gadget if you were already logged on to YAWL in another tab or window that session will remain active after the action completes if you were not already logged on you will automatically be logged on to enable the processing of the work item then logged out again when the processing completes Close this page to return to the iGoogle tab window and refresh the iGoogle page to show any newly available work items or queue changes caused by your actioning of the work item 142 CHAPTER 6 THE RUNTIME ENVIRONMENT Chapter 7 The Worklet Service This chapter contains instructions for installing and using the Worklet Dynamic Process Selection amp Exception Handling Custom Service for YAWL Each section describes one part in the process of setting up and using the Worklet Service It is probably best to work through the manual from start to finish the first time it is read This manual focuses on the practical use of the Worklet Service For those interested a more technical description of the inner operations of worklets and the rule sets that support them can be found in the technical manual A more concise version of the worklets approach can be found in 9 while a more concise version of the exlets approach can be found in 8 The ultimate reference on worklets and exlets is Michael Adams PhD thesis 7 All these publications can be downloaded from www yawlfoundation org All of the example specifications rule se
246. ourceforge net projects yawl In posting a question request or comment please help us as much as possible in answering you by explicitly stating which versions of various software components you are using providing the specification that is causing a problem listing messages produced in the console window and or log files providing a backup of the database and so on The YAWL Issues Tracker code google com p yaw1l can be used for reporting bugs or proposing enhance ments As attachments can be easily provided this is the preferred method for reporting bugs or requesting enhancements Again please provide as much relevant information as possible Also before reporting an issue carefully search the list to ensure that the issue has not already been reported Any feedback regarding this manual is most welcome and may be sent to yawlmanual gmail com We encourage forum posts bug reports and enhancement requests Providing these centrally means that others can learn from the answers provided and hopefully people are inspired to respond to other people s requests In this way we can manage progress on YAWL more efficiently 209 210 CHAPTER 9 SEEKING HELP Bibliography 1 2 10 W M P van der Aalst The application of Petri nets to workflow management Journal of Circuits Systems and Computers 8 1 21 66 1998 W M P van der Aalst L Aldred M Dumas and A H M ter Hofstede Design and implementation of
247. outing Plugin Task icons Modeling canvas ge NONE AND B E XOR OR Decorations Notes amp Problems panel Notes Invalid Resource References An invalid resource reference in Task Loss Or Damage Management of Net Loss_Or_Damage_Management has been removed An invalid resource reference in Task Process Freight Payment of Net Process_Freight_Payment has been removed An invalid resource reference in Task Prepare Transportation Quote of Net Carrier_Appointment has been removed An invalid resource reference in Task Arrange Delivery Appointment of Net Carrier_Appointment has been removed Use the palette toolbar to edit the selected net Hints amp Messages Engine Status Resource Service Status Figure 4 2 The YAWL Editor Workspace 4 2 THE YAWL EDITOR WORKSPACE Al 4 2 1 The Toolbar The Menu Toolbar contains eight groups of buttons to assist you in maintaining your YAWL specification The menu can be repositioned by dragging the left hand anchor bar Each button may be enabled or disabled at certain times depending on what you are doing in the Editor Specification Maintenance This group of buttons provides the standard file options left to right e Create a new specification e Open an existing specification file Specification files will have a yawl extension or sometimes a xml extension if they are an engine file created with a pre 2 0 Editor version
248. oval as a separate task In all we ve identified six distinct pieces of work Place six atomic tasks onto the starting net and give each a meaningful label You should have the skeleton of a workflow that looks something like figure 3 2 We re now ready to begin describing how the tasks in our starting net are to be ordered in their execution known as its control flow The transfer of work between two tasks is done through a flow Flows are depicted within YAWL as unidirectional arrows For a YAWL specification to be valid every task must be tied into a net via flows that can be traced back to the net s input condition and which will eventually lead to the net s output condition We ll need a flow from the input condition to the Receive and Validate Application task then two flows from that task to the tasks Determine Credit Requirements and Obtain Credit Report respectively From each of these a flow must go to the task Choose Approval Process From this task we need a flow going to the tasks Large Credit Approval and Small Credit Approval respectively From these last two tasks we need flows to the final output condition By default a YAWL task can only have one incoming flow and one outgoing flow When we need more incoming flows to a task we must unambiguously state how the task should handle its inflows should it wait for all of them Should it wait for only one of them Or something in the middle This disambiguation
249. ow examples of each of these When the Exception Service is enabled it is notified whenever any of these exception types occur for every process instance executed by the YAWL Engine by various means The Exception Service maintains a set of rules described in detail in Section 7 5 2 that are used to determine which exception handling process if any to invoke If there are no rules defined for a certain exception type for a specification the exception event is simply ignored by the service Thus you only need to define rules for those exception events that you actually want to handle for a particular specification Constraint Types Constraints are rules which are applied to a workitem or case immediately before or after execution of that workitem or case begins Thus there are four types of constraint exception e CasePreConstraint case level pre constraint rules are checked when each case i e instance begins execution e ItemPreConstraint item level pre constraint rules are checked when each workitem in a case be comes enabled i e ready to be checked out e ItemPostConstraint item level post constraint rules are checked when each workitem moves to a completed status and e CasePostConstraint case level post constraint rules are checked when a case completes The Exception Service receives notification from the YAWL Engine when each of these events occur then checks the rule set for the case to determine firstly
250. ow system what data they need to supply the workflow system and how the workflow system will use data to implement automated choice between alternatives Concerns involving workflow data are covered in section 3 4 2 3 4 ADVANCED WORKFLOW CONCEPTS 29 ao YAWLEditor Users adamsmj Documents research temp gs2 yawl aA L Task Icon No Icon b gt Manual Determine iir gt io Automated Credit Approval Routing Requirements a Plugin a Receive and Validate Approval Application Process Obtain Small Credit Credit Report Approval Select a number of net elements to manipulate Figure 3 4 Multiple Flows Between Tasks 3 4 1 Modelling Resourcing Requirements It s time now to add detail to our YAWL specification describing which participants should be doing particu lar pieces of the work specified We ll assume that the entire workflow is to be carried out by the Applications Department of Loans R Us All employees within this department are capable of performing the role Credit Officer but a subset of these with several years of experience also perform the role Senior Credit Officer Anyone with the Credit Officer role is allowed to approve small credit applications Only those performing the role Senior Credit Officer are allowed to do the final approval of large credit applications We therefore have a modelling requirement where every credit officer is capable of
251. ows of a task in a cancellation set is this If a flow relation connects two tasks directly then it is said to contain an implicit condition If there is a condition object in the model between two tasks so that the connection is task flow condition flow task for example the Knowledge Gained condition in Figure 4 16 it is said to be an explicit condition In either case when a task completes it passes control to the condition preceding the next task in the flow When the next task is started it takes control from its preceding condition whether implicit or explicit If there is a chance that the tasks in a cancellation set may not have started when the owner task of the set completes then cancelling those tasks will have no effect it is their preceding conditions that have control and so they are the elements that must be cancelled By including both tasks and their preceding conditions we are ensuring that the desired cancellation will occur regardless of whether the tasks in the set are currently executing or not To remove an element from a task s Cancellation Set 1 First make sure you have the View Cancellation Set option ticked for the task If it isn t ticked select the task that has the Cancellation Set right click then choose View Cancellation Set 2 Select the element for removal 3 Click on the Remove Selected Items from Visible Cancellation Set button FA on the Menu Toolbar
252. pRegistrationType Also the variable customer has an initial value of Type name of customer as a prompt for the customer to enter his her name Update Net Variable customer F4 Update Net Decomposition Make Trip Process Standard Extended Attributes Net Decomposition Label Make Trip Process PRF Name customer Type string Net Decomposition Variables Usage Local Name Type Usage Initial Value customer string Local a Please type name iregistrinfo tripRegisterType Output Only flightDetails string Local hotelDetails string Local carDetails string Local Canca Figure 5 15 Net variable definitions Figure 5 16 shows the parameter definition of task register with two task variables The input amp output variable customer gets the customer s name and then passes it to the net The output only variable registrInfo requests registration information from the customer and then passes the data to the corresponding net variable via the XQuery register registrInfo Figure 5 17 shows the flow definition at task register The predicate for the flow leading to task book flight is Make Trip Process registrInfo want flight true Similarly the predicate associated with the flow leading to task book hotel or book car is to determine whether the variable want_hotel or want_car 110 CHAPTER 5 HOW TO MANIPULATE
253. pplication large Domainic If the application is for 5 000 or more it s considered large Any lesser amount is considered a small application and can be done by anybody in our department Processa takes this transcript dumps it on your desk and tells you to implement a workflow to match What s more she wants you to do it with YAWL In a nutshell a workflow specification in YAWL describes what work needs to be done when and by whom Each YAWL specification is composed of one or more YAWL nets exactly one starting net also known as the root or parent or top level net and zero or more sub nets In this tutorial we ll keep things simple and we will only consider the case of a YAWL specification composed of one net the starting net A net has two mandatory elements an input condition which acts as the starting point graphically represented like this and an output condition which signals the end the symbol Figure 3 1 depicts the YAWL Editor 3This chapter is more an overview of YAWL than an examination of its tool support The assumed knowledge at this point is that you have installed and can begin using the YAWL toolset by following the instructions provided in Chapter 2 26 CHAPTER 3 GETTING STARTED WITH YAWL with a brand new specification open and with the specification s starting net visible Don t worry too much at this stage about the various components of the Editor it is described in detail in Chapte
254. process instance the meaning in terms of workflow processes is much broader exceptions are merely events or occurrences that for one reason or another were not defined in the process model It may be that these events are known to occur in a small number of cases but not enough to warrant their inclusion in the process model or they may be things that were never expected to occur or may be never even imagined could occur In any case when they do happen if they are not part of the process model they must either be handled off line before the process continues and the way they are handled is rarely recorded or in some instances the entire process must be aborted Alternately an attempt might be made to include every possible twist and turn into the process model so that when such events occur there is a branch in the process to take care of it This approach may lead to very complex models where much of the original business logic is obscured and doesn t avoid the same problems when the next unexpected exception occurs The Exception Service addresses these problems by allowing you to define exception handling processes that may include worklets as compensation handlers for parent workflow instances when certain events occur Rules are defined in much the same way as for the Selection Service but with added features that enable you to pause resume cancel or restart the task case or all cases of a specificati
255. processing a credit appli cation right through from its receipt to approval so long as the application is for a small amount When it comes to the step of approval for large credit applications however only senior staff are allowed to do this approval We first need to establish an organisation model within a running YAWL system where we identify those participants from the Applications Department For each of these we assign the Credit Officer role For the subset of participants recognised as senior we also assign an extra role of Senior Credit Officer To define this organisational model you need to log into the YAWL Resource Service for now we ll use the generic username admin and password YAWL Assuming you used one of the automatic installers this is simply a matter of starting the engine choose Start Engine from the options shown for the YAWL program followed by starting the Resource Service choose YAWL Control Centre from the options shown for the YAWL program When you have logged in you can create new roles by choosing the Org Data Met form from the menubar and new participants by choosing the User Mgt form from the menubar This is illustrated in Figure 3 5 where the role Senior Credit Officer is defined and Figure 3 6 where the participant Michael Corleone is defined and assigned that role Once we have defined all the required roles and participants we can specify resourcing requirement
256. r _ Task Variable i fCredit_Rating Process rating pns e r add KGuery of element s content z A add XQuery of entire clement XQuery arall Credit_ Rating Process rating texe Net Variables Task Variables Name Type Usage Name Type Usage san string Local a cating double Output Only a rcating double Local fault string Local Output Parameters waue _NetVariable Greate Ead Update lt ul gt Remove populates the task variable Figure 5 10 Parameter definition for task Decide Rating were founded in this specification The last step before deployment is to specify the resource details for each of the manual tasks i e ReceiveSSN DecideRating and ReportFault In Chapter 4 Section 4 10 illustrates how to allocate resources to a manual task via the resource manager wizard To keep things simple we will choose to not specify any resourcing details for those task in doing so each of those tasks will be assigned the default settings that offering allocating and starting a work item are all to be done by the User at run time 5 5 ILLUSTRATIVE EXAMPLES 107 Finally we save the CreditRatingProcess to file which can be deployed uploaded in the engine and executed by launching a case Examples of Design time Run time Errors The above YAWL specification is both syntactically and semantically well formed and can be executed without
257. r 4 YAWLEditor WIL alm gt jeja matin ww 4 SSN O mja pi OO L Task Icon No Icon i a Manual gt m Be why Automated gt 4 Routing J Plugin Left click on the selected net to create a new atomic task Figure 3 1 A New Specification and its Starting Net It s time to start modelling the work to be done Typical workflow specifications in YAWL will make significant use of atomic tasks An atomic task represented in YAWL as a square models a stand alone piece of work that is either manual or automatic and it s here that workflow designers starts earning their money Just how much work should a single atomic task represent The answer is not always obvious Looking again at Processa s transcript we decide that an initial atomic task is needed for receipting and validating a claim After that two additional pieces of work need to be done but in no particular order We ll add an atomic task each for determining credit requirements and seeking a credit report The next step requires that both credit requirements are determined and that a credit report be ready We need an extra task to run only once they are finished which will decide based on the application amount whether we then send the application on for a large or a small approval process We expect large approvals and small approvals to have differing work requirements so we ll model each type of appr
258. r more participants Reallocated to a single participant or Restarted to a single participant While the queues are refreshed whenever the page is loaded you may also refresh the queue contents by clicking on the refresh icon located at the top right of the work queues panel If the Directly to me checkbox is unchecked when one of these buttons is clicked a list of all participants will be displayed from which selections can be made If the checkbox is checked the action triggered by the button click will occur as if the currently logged on participant had selected themselves from the list thus bypassing the list display The Directly to me checkbox is available only to participants with administrator privileges but the to the generic admin userid since admin is not a participant it cannot have work items assigned to it The Resource Service maintains a local cache of active work items On rare occasions this cache may become out of synch with the list of active work items maintained by the Engine for example where another custom service has modified the status of a work item The Synchronise icon to the left of the refresh icon allows administrators to re synchronise the local cache with that of the Engine The results of any changes brought about by re synchronisation can be noted in the Tomcat log files There are some system overheads involved with re synchronisation and it is rarely necessary so may occasionally
259. r own data types to be used in the specification Net In addition to the Net Maintenance toolbar items this menu also contains these sub items e Set Starting Net for specifications containing several nets this item allows you to specify which of them is the starting net i e the net that begins execution of the workflow instance e Update Net Detail shows a dialog where you can set the name of the net and create update remove net level variables e Export to PNG Image saves a graphical image of the net to a file e Net Background Colour set the background colour of the selected net e Print Net prints the currently selected net graphically Edit In addition to the Edit Options toolbar items this menu also contains sub items to Cut Copy and Paste objects to from the canvas Elements This menu contains the Alignment Options Object Sizes and Cancellation Set toolbar item sets You can also set the fill colour for all selected tasks and conditions using this menu Tools This menu contains the following items e Engine Connection Settings The Editor must connect to a running Engine to obtain a list of the available services that a task can be assigned to This menu item allows you to set the parameters for a connection to the Engine and to proceed with a connection e Resource Service Connection Settings The Editor must connect to a running Resource Service to obtain a list of the available resources th
260. rder Fulfilment Manager PO Manager i All members of this role must Senior Credit Officer first undertake a 12 week Senior Finance Officer training course in Beverage Senior Supply Officer Preparation and Management Shinmeant Planner Add New Junior Coffee Maker Figure 6 6 Adding a New Role for an example on the Role tab page Enter a name for the entity and optionally a description and note choose the entity it belongs to and or reports to as required see below then click the Add button You may cancel the addition at any time by clicking the Reset button instead of the Add button e To Modify an entity select it from the list then add or change its description note belongs to and or reports to then click the Save button e To Delete an entity select it from the list and click the Remove button With regards to the belongs to and reports to relations e A role may belong to another role you may set this relation using the Belongs To dropdown on the Roles tab page This allows a hierarchy of roles to be created so that when a task is assigned to a role in the Editor and that role has other roles belonging to it those roles are also implicitly included by inheritance You will not be allowed to have a role belong it itself either directly or as part of a cycle back to itself for example if role A belongs to role B which in turn belongs to role C you will not be allowed to have role C belong
261. reated in the same way As depicted in Figure 4 23 the new data type Geek is available to choose from the list of available types when creating a task or net variable Variables with a usage of Local can have initial values specified for them as depicted in the same figure As with the data type definition dialog parse errors will be listed when the initial value text is red 4 5 3 Net Decomposition Detail Net Variables You can add variables to a net to store information relating to that net that tasks within the net may need to read or update To add a variable to a Net 4 5 ADDITIONAL SPECIFICATION FEATURES 63 e09 Update Data Type Definitions ale ee editimenu lt xs schema xmlns xs http www w3 org 2001 x LSchema gt lt xs complexType name Geek gt lt MS i sequence gt lt xs element name Name type xs string gt lt xs element name Salary type xs double gt lt XS Sequence gt lt xsi complexType gt lt xs complexType name Book gt lt XS i sequence gt lt xs element name Title type xs string gt lt xs element name Autor type xs istring gt lt xSBtsequence gt lt xs complexType gt lt xs complexType name Booklist gt lt xSisequence maxOccurs 5 gt lt xs element name Book type Book gt lt xStsequence gt lt xs complexType gt lt xstschema gt Figure 4 21 Adding the Geek complex data type 1 Choose Update Net Detail from
262. riable itineraryseqment gt rdo itinerary segment leg depart itinerary Figure 5 25 Parameter definition of task do itinerary segment Figure 5 26 shows the instance details for task do itinerary segment The left tab window titled Bounds is for specifying the task attribute data i e the maximum and minimum number of instances allowed and the threshold value The right tab window titled Queries is for defining the multiple instance data specific to individual execution instances of task do itinerary segment for each leg within one itinerary i e a single process instance There are four queries Firstly an accessor query manipulates the overall data carried by root net variable legs before the data is split out to each individual leg This query determines the input parameter definition for variable leg Secondly a splitter query separates the unique values from the overall data carried by variable legs and passes a unique value to variable leg associated with each instance The data returned on completion of an instance is an XML document Thirdly an instance query transforms such an XML document to a form that is suitable for aggregation of data to the higher level i e the root net make trip This query determines the output parameter definition for root net variable itinerary Finally an aggregate Query generates an overall result and passes the data to variable itinerary on completion of all instances of tas
263. rivileges for a participant select the participant from the dropdown list tick the Administrator checkbox then click the Save button Administrator privilege overrides all other user privileges Partici pant s without administrator privileges may be granted specific privileges by selecting the participant from the dropdown list then ticking the desired privileges then clicking the Save button The privileges that may be assigned to participants on an individual basis are e Choose Which Work Item to Start When granted this privilege allows a participant to choose any work item listed on their allocated queue to start When denied the default only the first listed work item may be chosen Work items are listed in order of age with the oldest work item at the top of the list e Start Work Items Concurrently When granted this privilege allows a participant to have a number of work items executing concurrently on their started queue or more accurately may choose to start additional work items from their allocated queue while other previously started work items have not yet completed When denied the default a work item on the participant s allocated queue may not be started while there is a previously started work item on their start queue i e one that has not yet completed 6 3 ADMINISTRATION 131 e Reorder Work Items When granted the participant may choose a work item to start from anywhere in the list of allocated work item
264. rk any version If you don t have the framework installed it can be downloaded for free from Microsoft http www microsoft com downloads The Rules Editor tool is found in the rulesEditor folder of the worklet repository It can be executed directly from there no further installation is required For more details on the Rules Editor and how to use it refer to Section 7 5 2 148 CHAPTER 7 THE WORKLET SERVICE Se Worklet Rules Editor lt Browse gt Casualty_Treatment a File Rule Options Help M a Rule Type Selection Task Name 7 eat AOR Tree Comerstone Case PatientID 2375493 Sen ha Diastolic EF 95 Height 1 65 Hearthate 80 SpstolicbP 140 Fracture false Age 35 Weight 72 Fever false Rash falze Wound true Name Ben Dover Selected Node Mode ID 2 Parent Node ID i Condition Wound true Conclusion 1 select Treaty ound Description basic worklet for a wound Figure 7 5 The Worklet Rules Editor 7 3 Using the Worklet Selection Service Fundamentally a worklet is nothing more than a workflow specification that has been designed to perform one part of larger or parent specification However it differs from a decomposition or sub net in that it is dynamically assigned to perform a particular task at runtime while sub nets are statically assigned at design time Also worklets can be added to the repertoire at any time during the life of a specification even
265. rkflow engine A second use is for passing data between web services and or external code 66 CHAPTER 4 THE EDITOR 60e Update Net Variable Extended Attributes Name StudentNumber Type string HH Usage Initial Value Done Cancel Figure 4 25 The Net Variable Student Number A Update Net Decomposition Attend_University Net Decomposition Label Attend_University Net Decomposition Variables Create Update Remove ae Figure 4 26 Updated Attend University Net Variables and or applications that the running workflow engine invokes and the Net the task resides in For example if your task is called Purchase a Book you may want to store the name and or ISBN of the book being ordered 4 5 6 Adding a Variable to a Task 1 First select the task that will require the variable ra We will be setting up variables for the Enrol task Go to the Attend University Net and select the Enrol task 2 Right click on the task and choose Task Decomposition Detail An Update Task Decomposition 4 5 ADDITIONAL SPECIFICATION FEATURES 67 e800 Atomic Task Get a Job Set decomposition to Get_a_Job H Feel_Smarter m Pass_All_Subjects Begin_My_Career a Read_a Book i Look_for_an_Easier_Book Get_Degree Career_Started kd Figure 4 27 Select Task Decomposition example Get a Job task dia
266. rocess model will be modified to capture this unforeseen event which involves an organisational cost downtime remodelling testing and so on The Worklet Dynamic Exception Handling Service or Exception Service provides the ability to handle these events in a number of ways and have the process continue unhindered Additionally once an unexpected exception is handled a certain way that method automatically becomes an implicit part of the process specification for all future instances of the process which provides for continuous evolution of the process but avoiding the need to modify the original process definition The Exception Service uses the same repertoire of worklets and dynamic rules approach as the Selection Service The difference is that while the Selection Service is invoked for certain tasks in a YAWL process the Exception Service when enabled is invoked for every case and task executed by the YAWL engine and will detect and handle up to ten different kinds of process exception As part of the handling process a process designer may choose from various actions such as cancelling suspending restarting and so on and apply them at a workitem case and or specification level The Exception Service is extremely flexible and multi faceted and allows a designer to provide tailor made solutions to runtime process exceptions as described in the following pages 7 2 INSTALLATION 145 7 2 Installation 7 2 1 Worklet Ins
267. rship of roles etc a value greater than 100 is treated as 100 A value of 1 the default turns off random org data generation If you do make use of this feature don t forget to reset the value to 1 after the generation is done e EnableVisualizer When set to true an extra button will appear on user work queues to show work items via the Visualizer applet assumes the visualizer is available The default setting is false e InterfaceX_BackEnd This parameter is commented out by default When the commenting is re moved the extensions to the work queues required for the Worklet Service are enabled 6 2 Logging On To log on to YAWL 1 Start the YAWL engine by choosing the option Start Engine from the YAWL program menu 2 Start the Resource Service either by choosing YAWL Control Centre or by pointing your browser at http localhost 8080 resourceService 3 Login with an existing userid and password First time logon i e where there are no participants defined in the organisational database should use the generic userid admin and password YAWL Note that a participant with administration privileges will have available the full menu of buttons as shown in Figure 6 1 ordinary participants and participants with some extra privileges will see a subset of those buttons when they log on The admin userid is a special logon which can be used for administrative tasks only because it i
268. rticipant must have the task privilege Can Delegate and have subordinate staff to successfully deallocate a work item e Skip This action skips the execution of the work item that is the work item is immediately started and then completed allowing the process to continue according to its subsequent control flow A participant must have the task privilege Can Skip to enable the skipping of a work item e Pile When a work item is piled the work item is immediately started and placed in the participant s started queue Furthermore each and every future instance of the work item across all cases of the same specification is automatically allocated to the participant and started completely ignoring any resourcing specification for the task from which the work item is created To put it another way by piling a work item a participant is entering into a contract with the Resource Service asking that this work item and all future occurrences of such work items created from the same task description as the original work item was created from be immediately allocated and started to him her Piling of such work items continues until the participant turns off piling for the task via the View Profile form or the participant logs out if so configured A participant must have the Can Pile task privilege to enable piling 6 4 3 The Started Queue The Started queue lists the work items that have been started by or for a participa
269. ruction 4 1 Launching the YAWL Editor The Editor is installed along with the other YAWL System components using any of the installers described in Chapter 2 It can also be installed manually by downloading the latest version from the YAWL SourceForge website http sourceforge net projects yawl Be sure that the version number of the Editor you are using matches the version of YAWL installed The YAWL Editor is distributed as a Java Archive jar Double click on the YAWLEditor2 0 jar file to start 39 40 CHAPTER 4 THE EDITOR the application where supported The YAWL Editor can also be started from a command line or Terminal prompt java jar YAWLEditor2 0 jar 4 2 The YAWL Editor Workspace The first time you start the YAWL Editor you will be presented with a blank canvas and a prompt in the Status Bar asking you to open or create specification to begin Before you create your first specification let us take a brief tour of the Editor s workspace and the elements within the use of each element is fully described in later sections The workspace is shown in Figure 4 2 Net Alignment Cancellation Maintenance Options Sets 4 4 Specification Maintenance Specification Net Edit Elements Tools lale Blelejie e iew Help Specification Verification Edit Size Zoom and Analysis Options Options Options Wf Elements amp ci Task Icon Tools No Icon Manual a Automated ca 0 R
270. rvice but there are many others and advanced users are able to define and add virtually any service they want The external service eventually finishes its execution resulting in values being supplied to the output parameters of the task instance The output mappings for this task instance are then executed resulting in a number of parameters in the task s containing net instance being updated with values from the task instance s output parameters Now we have a basic understanding of data transfer in YAWL let s start specifying the data transfer require ments of our workflow specification Since all data are passed as XML documents all data types are defined using XML Schema Language there are over 40 in built XML Schema data types and YAWL allows users to also define their own For our example will limit our parameters to be of either XML Schema string or double simple types We ll go through our atomic task decompositions now and add parameters to each task decomposition first before we add the necessary data transfer mappings for moving data between tasks and their containing net Imagine that we have finished an exercise of determining what data must be passed out of YAWL at the starting of each task of our specification and what data must be returned back into the system when each task completes We note through the exercise that even though the tasks Large Credit Approval and Small Credit Approval are done by differ
271. s When denied only the first listed work item may be chosen In the YAWL environment there is essentially no difference between this privilege and Choose Which Work Item to Start e View All Work Items of Team When granted this privilege gives a participant access to the Team Queues form and displays on that form a consolidated list of all work items on all work queues of all participants subordinate to the participant who has been granted the privilege that is participants holding positions that report to a position held by the granted participant either directly or through a hierarchy of positions When denied the default the Team Queues form is not available to the participant e View All Work Items of Org Group When granted this privilege gives a participant access to the Team Queues form and displays on that form a consolidated list of all work items on all work queues of all participants in the same Org Group as the granted participant When denied the default the Team Queues form is not available to the participant e Chain Work Item Execution When granted this privilege allows a participant to chain work items for a case When denied the default the participant may not chain cases see Section 6 4 for details regarding the chaining of tasks e Manage Cases When granted this privilege gives a participant access to the Case Mgt form pro viding the ability to load process specifications and start and cancel cas
272. s captured through the use of XML Schema XPath and XQuery e YAWL offers comprehensive support for the resource patterns It is the most powerful process specifi cation language for capturing resourcing requirements e YAWL has a proper formal foundation This makes its specifications unambiguous and automated verification becomes possible YAWL offers two distinct approaches to verification one based on Reset nets the other based on transition invariants through the WofYAWL editor plug in e YAWL has been developed independent from any commercial interests It simply aims to be the most powerful language for process specification e For its expressiveness YAWL offers relatively few constructs compare this e g to BPMN e YAWL offers unique support for exceptional handling both those that were and those that were not anticipated at design time e YAWL offers unique support for dynamic workflow through the Worklets approach Workflows can thus evolve over time to meet new and changing requirements 7 8 CHAPTER 1 INTRODUCTION e YAWL aims to be straightforward to deploy It offers a number of automatic installers and an intuitive graphical design environment e Through the BPMN2YAWL component BPMN models can be mapped to the YAWL environment for execution e The Declare component released through declare sf net provides unique support for specifying workflows in terms of constraints This approach can be combined w
273. s for tasks Right click with your mouse on a task and choose Manage Resourcing from the popup menu this menu 30 CHAPTER 3 GETTING STARTED WITH YAWL e080 YAWL 2 0 Organisational Data Management lt gt 3 a 36 oo anit u http localhost 8080 resourceService faces orgDataMgt jsp ar p cls Google OnYsA we LO Sa ee ee oe er Description Belongs To nt Manager Can approve applications for nil x Carrier Admin Officer amounts exceeding 5000 Notes Order Fulfilment Manager PO Manager Senior Finance Officer Save Add Senior Supply Officer Shipment Planner Add New Senior Credit Officer Figure 3 5 Defining a Role item will be disabled for tasks without decompositions defined The Resourcing Wizard will begin and you can choose the interaction strategy for that task In Figure 3 7 an interaction strategy is chosen where at runtime the system offers a work item to all authorised participants from where one of these participants can then choose to perform this work item and later choose to actually start working on it This strategy Offer System Allocation User Start User is a common interaction strategy for tasks to be executed by participants Step 2 of the Resourcing Wizard then allows you to choose who is authorised to execute work items of the particular task In Figure 3 8 the Senior Credit Officer role is assigned to the task thus guaranteeing that a
274. s less than expected Example used to test workletService Exception Handling Running Cases 8 OrganiseConcert 0 1 9 Change ToMidVenue 0 1 Figure 7 47 Case Mgt Screen OrganiseConcert case running from the list then clicking the Raise Exception button at the top right toolbar the green forked arrow within the tabbed area see Figure 7 49 You will be taken to the Raise Item Level Exception screen where the procedure is identical to that described for case level exceptions except that the item level external exception triggers if any will be displayed External exceptions can be raised at any time during the execution of a case the way they are handled may depend on how far the process has progressed via the defining of appropriate rule tree or trees E Exception Timeout Example When a workitem has an associated timer that times out expires the Engine notifies the Exception Service and informs it of all the workitems running in parallel with the timed out item Thus rule trees can be defined to handle timeout events for all affected workitems including the timed out item itself The specification TimeoutTest3 gives an simple example of how a timeout exception may be handled Fig ure 7 50 Upload the specification via the Case Mgt screen and then launch the case The first workitem Fill Order simulates a basic purchase order for a bike Check out the Fill Order workitem accept the default va
275. s not a formal participant i e it is not a logon associated with a unique person it has no access to an individual work queue so the menu options for Work Queues Team Queues and Edit Profile are not available for the admin logon 6 3 Administration A workflow administrator can load new workflow specifications can start cases for them can register or remove custom services and add and manage participants roles positions and organisational groupings In this section we will explore how these functions are achieved 6 3 1 Case Management To upload a new workflow specification first click Case Mgt in the top menu which displays in the screen shown in Figure 6 1 Upload the specification by browsing to the particular file and clicking the Upload File button in the Upload Specification panel Only files with a yawl or xml extension can be uploaded When a specification is uploaded it is validated against the YAWL specification schema for validity If there is a problem with the upload an appropriate error message is displayed at the bottom of the screen Cases can be launched for a specification by selecting it from the list of loaded specifications then clicking the Launch Case button in the Loaded Specifications panel If the specification has input parameters a form will appear asking for values for these parameters to be provided Note that trying to upload a specification that has already been uploaded i
276. s that are of string type and have one of those usage types will be listed in the Net Parameters table and will initially all be set as referring to Data For each of those that will contain resourcing information at runtime the Refers To value must be changed to either Participant or Role via the drop down list on each row depending on the type of resource the value will refer to at runtime Step 3 In Step 3 shown in Figure 4 51 we can filter the set of participants that have been described in Step 2 Filtering can be done over capabilities and or over positions and organisational groups Moreover from this dialog it is possible to e allow the work items of the selected task to be offered only to participants who are members of the set specified in Step 2 and have previously completed work items of another task as specified in the current process instance A role is essentially a set of participants 90 CHAPTER 4 THE EDITOR 486080 Manage Resourcing Wizard for Atomic Task A Step 2 Specify System Behaviour when Offering a Work Item The offer process involves choosing which participants should be informed of the existence of the work item one of whom will eventually do this work As you have specified the system manage the offer process you must now choose who the work item should be offered to Begin by specifying a set of participants and or to distribute offers of work to You may also specify a net par
277. s those in Figure 4 32 the XQuery expressions for the input parameters follow the form name_of_net name_of_variable text and are mapped to a task variable while those for output parameters follow the form name_of_task name_of_variable text and are mapped to a net variable e An Input Usage mode means that the variable requires a value to be mapped into it when its task starts via an input parameter An Output Usage mode means that the variable is required to map a value from it typically to a net level variable when its task completes via an output parameter An Input Output Usage mode combines both requirements e Only Net level variables may have a Usage mode of Local which signifies a scope within the net but not external to it Thus sub nets require net level variables with modes other than Local to support data passing to and from their parent nets A root or top level net with variables of type Input Only or Input amp Output will when started request values for those variables from a user via a form before the first task in the net is activated No action is taken for Output modes set for root net variables e Input parameters may only be created for variables of mode types Input Only or Input amp Output e Output parameters may only be created for variables of mode types Output Only or Input Output 4 5 8 Flow Detail When dealing with tasks that have XOR and OR splits we need some way of defining whi
278. se only the Default Worklist of the Resource Service will be available When you select a YAWL Service the Editor will query this running engine for the mandatory input and output variables required by the service if any and will populate the decomposition variables of the selected task with those variables Core custom services that are supplied with the engine include one for RPC Style Web Service Invocation WSInvoker Service and one for supporting flexibility and exception handling for YAWL processes Worklet Service Optional services include an SMS handler a digital signature service and a email sender service 4 7 VALIDATING AND SAVING A SPECIFICATION Sl 4 7 Validating and Saving a Specification At any stage you can validate and or save your specification to a YAWL Engine file yawl To validate your specification 1 Click the Validate button iy on the Menu Toolbar or click Specification on the Menu and choose Validate Specification 2 If problems are detected a table listing them will appear at the bottom of the Editor with details of any inconsistencies that would stop the specification from running in the YAWL Engine Figure 4 41 show a specification with no validation problems Figure 4 42 shows an example invalid specification where the Validation Problems table shows that the Bad Task task has no outgoing flow and is not on a path between the input and output conditions af Aa YAWLEditor Users
279. se Mgt page to see that the BobOne BobTwo and BobThree specifications have been uploaded and launched by the Worklet Service as separate cases Figure 7 40 note the case numbers Go back to the Work Queues page and check out all three workitems Edit each of the Get_Bob workitems and modify the values as you wish for this walkthrough we ll change the values to one five two six 7 6 WALKTHROUGH USING THE WORKLET SERVICE 179 starting an Instance of wListMaker fo 00 Enabled Jule 2009 13 14 32 0 00 00 01 Figure 7 39 Workitems from each of the three Launched Worklet Cases and three seven respectively As you edit and complete each Get Bob workitem the corresponding Verify List workitem from the parent instance is automatically checked in to the Engine by the Worklet Service Since the Bob worklets contains only one task editing and completing this workitem also completes the worklet case 180 CHAPTER 7 THE WORKLET SERVICE Loaded Specifications BobOne A Worklet to enact when bob is one BobThree l Worklet to enact when bob is three BobTwa Worklet to enact when bob is two wListMaker D A process to demonstrate how worklets handle a multiple task Running Cases 3 wWListMaker 0 1 4 BobOne 0 1 5 BobThree 0 1 6 BobTwo 0 1 Figure 7 40 Bob Specifications Loaded and Launched by the Worklet Service After the third workitem has been edited and completed and s
280. served externally and the variables of composite tasks serve as intermediate variables for passing data from the higher level to the lower level of a process and vice versa e g between a net and the tasks in its subnets When data are required from the external environment at run time either a web form will be generated requesting the data from the user or a web service will be invoked that can provide the required data 5 3 2 Valid and Invalid Data Transfers To ensure correct data transfer YAWL defines a set of transfer rules for variables of different data usage Each input variable except those associated with the top level net root net must have data supplied from the corresponding net variables which could be a single net variable or an aggregation of any number of net variables via an input parameter definition An input variable of the top level net gets data supplied from the environment e g a user input once an execution of the net is started a local variable of the top level net may be assigned an initial value at design time data assignment Each output variable except those associated with composite tasks requests data from the environment once the corresponding net or task is executed An output variable associated with a composite task gets data via the net data in its subnet using an output parameter definition Otherwise output variables are used to supply task data to corresponding net level variables in intern
281. sidered complete and will trigger relevant outgoing flow relations from this task Set the Continuation Threshold to 50 8 Click Done 54 CHAPTER 4 THE EDITOR With the values set in the scenario it has been specified that the Do Private Study task can have a maximum of 100 instances created a minimum of five instances will be created and once 50 instances or all those started if less than 50 have completed the outgoing flow relation to Get A Job will trigger We will revisit the setting of parameters for multiple instance tasks in particular the details of the Queries tab of the Multiple Instance Detail dialog in Section 4 5 9 after the basics of queries have been introduced 4 3 4 Multiple Instance Composite Tasks Multiple Instance Composite Tasks allow you to run multiple instances of the sub net represented by a multiple composite task concurrently To create a Multiple Composite Task 1 Click on the Add Multiple Composite Task button a in the Elements panel or right click in an empty part of the canvas and choose Multiple Composite Task Go to the My Career Net We are going to replace our existing Do Private Study Multiple Instance Task with a Multiple Composite task so click on the Do Private Study Task and delete it We will add in the new Multiple Composite task next 2 Place your Multiple Composite Task in your Net Reconnect the Flow Relations from Begin My Career
282. similar to Figure 7 22 If the No button is clicked then the new rule is simply added to the rule set Result of replace request Locating workitem 4 35 3 Treat in the set of currently handled workitems Found Cancelling running worklet case with case id 5 For workitern done Launching new replacement worklet case based on revised ruleset done The Worklet TreatHighHeartRiate has been launched For workibern 43 3 Treat and has case id 6 Figure 7 22 Result of Replace Request Dialog Figure 7 23 shows the main Rules Editor screen with the new rule added in the correct place in the tree with the current case data becoming the Cornerstone Case for the new rule 7 5 7 Creating a New Rule Set and or Tree Set As mentioned previously it is not necessary to create tree sets for all of the rule types nor a rule tree for an item level rule type encompassing every task in a specification So most typically rule sets will have 7 0 WORKLET RULE SETS AND THE RULES EDITOR 167 Se Worklet Rules Editor lt Browse gt Casualty_Treatment m File Rule Options Help ajal DKI Rule Type c lection Task Name Tet AOR Tree Comerstone Case PatentID 98769067 Rule 1 zex F Bule 2 DiastolicBP 110 q niz Height 1 57 Rule 10 HearHate 190 Rule 2 SystolicbP 165 Rule 3 Fracture false Age 66 a weight 107 Fiule 5 Fever false L Rule 3 Rash true Wound false Name Garnmy Ticker Selected No
283. ssigns 4 5 ADDITIONAL SPECIFICATION FEATURES 19 ae Update Parameters for Atomic Task Create Book List Input Parameters XQuery Task Variable Create List_Builder MasterList bookList h Update Remove Task Variables Name Type Usage bookList BookList Input amp Output Net Variables Name Type MasterList BookList Output Parameters XQuery Net Variable Create Create Book List bookList MasterList Update Remove Figure 4 35 Update Parameter Mapping dialog for task Create Book List each member of the list to a task instance and on output takes each task instance s variable and maps it back to the net level list The intermediary steps that allows this mapping to occur is done in the second stage of the mapping process Right click on the Verify List MI task and choose Set Instance Detail from the popup menu On the Bounds tab page set minimum instance to 1 maximum instances to 20 continuation threshold to 5 and static instance creation type These settings mean that between 1 and 20 task instances will by started from this MI task at runtime the MI task will complete when 5 instances complete or all complete if less than 5 were started and new instances may not be dynamically started after task execution begins Now click the Queries tab page It is here that we will specify how the BookOrders contained in the MasterList variab
284. t a specific date and time choose the at the time of radio button on the Set Timeout Detail dialog Figure 4 54 and enter the required values Care should be taken when setting a specific time value for timers if it happens that the specified value is earlier than the moment the task is actually enabled or started depending on when it is set to activate then the YAWL Engine will recognise that the 4 11 TASK TIMER 93 Manage Resourcing Wizard for Atomic Task Approve e09 Step 5 Establish Default User Runtime Privileges for this Task Can a participant suspend a started work item of this task Can a participant reallocate a work item of this task to another participant resetting state Can a participant reallocate a work item of this task to another participant retaining state Can a participant deallocate themselves from a work item of this task Can a participant delegate a work item of this task to another participant Can a participant skip a work item of this task lt Back gt Next Figure 4 53 Step 5 of the resource management wizard 808 Set Timeout Detail for Atomic Task Approve Wi Task is required to timeout Timeout dynamically via net variable approveTimer at the time of 17 07 2008 Ta 101 55 58 gt after a duration of al m h Timer begins upon work item enablement G upon work item starting Done Cancel Figure 4 54 The t
285. t case until such time as the rejection or unexpected exception is actioned by an administrator aA Aa Worklet Service Define New External Exception for Case Gs Cle Google ez amp gt gt E PS So ant Al v http localhost 8080 workletService newCaseException caselD 35 AOUT n Define New Case Level Exception Case ID Specification ID 35 OrganiseConcert Please complete each of the fields below Proposed Title Equipment Lost in Transit Scenario We were expecting to receive all of the band s equipment after the end of the Japan leg of the tour but it hasn t arrived and the shipper has not yet located it We will have to hire equipment for the Brisbane and Sydney concerts at this stage Process Description Work out what s needed get a couple of quotes hire the equipment get it delivered to the Brisbane venue Cancel Submit YAWL is distributed under the LGPL Done Figure 7 55 Example of a New Case Level Exception Definition Back at the Case Mgt form if the exception service is enabled you will notice an extra button in the Running Cases panel called Worklet Admin for example Figure 7 47 This button allows administrators to view the current list of outstanding worklet rejections and requests for new exception handlers It also allows administrators to view the details of each outstanding rejection and exception request and to mark it as completed remov
286. t it is the same XQuery expression as the task s input parameter as shown in Figure 4 36 Splitter Query the splitter is an XQuery expression that is used to take the list variable mapped in and split it into a number of child elements one for each member of the list In natural language the query reads for each element in the accessor variable return that element In our example the XQuery is for e in MasterList return lt book gt e lt book gt The e part is a query variable all query variables start with a sign followed by one or more characters e is a convention for a loop variable The return value for each e in our query would start and end with order tags since our variable is called book we have to replace the order tags with book tags so the return value of our XQuery is the contents of the order e but surrounded by book tags The final result is a number of book values each corresponding to one order element in MasterList Instance Query this query defines how the book variable within each task instance should be formatted prior to being mapped back to the net level MasterList Like the splitter query above we need to replace the surrounding book tags with order tags the contents of the element being the contents of the book variable Verify_list book Notice also that this query exactly
287. t parameters with the required data attributes above At present the WS Invoker Service supports only SOAP over HTTP and request response and one way interactions out in and out only message exchange patterns 197 198 CHAPTER 8 OTHER SERVICES 80e Update Task Decomposition Extended Attributes Task Decomposition Label CallWws Task Decomposition Variables Usage Create YawlWSInvokerWSDLLoc anyURI Input Only YawlWSInvokerPortN ch Input Only A Update Input Only nn Remove External Interaction _ Automated Set Codelet Done Cancel a a Figure 8 1 Task Decomposition Dialog for WSInvoker associated task 8 2 SMS Service The SMS service can use any third party SMS Gateway web service to send and receive SMS messages and pass the data into and out of the YAWL Engine In this way participants can view update and complete task instances via mobile phones and other SMS capable devices The service is pre configured in its web xml file with four values a userid and password for an SMS account known to the specified SMS Gateway web service and its send and receive URI s These values will be particular to each SMS Gateway service provider Like the WSInvoker Service when a task is associated with SMS Service by opening the Task s Decomposition dialog in the Editor and choosing the SMS Service from the list of available services Figure 8 2 the service will supply three var
288. t runtime work items of this task are offered only to participants that perform that role Resourcing requirements can be quite complex and the YAWL environment offers comprehensive support for the vast majority of workflow resource patterns but for the moment we will simply assign roles to the various tasks and apply the System User User interaction strategy 3 4 2 Modelling Data Requirements We now need to specify what data will be passed about during the execution of an instance of this specification Specifically we need to describe what data participants will need in each work item and what data they must return to the Engine once the work item is complete We also need to have a way of moving data about in the running workflow including how we can use that data to automatically choose between flows in a running workflow We stated before that task decompositions are used to define how a running workflow interacts with the external environment In fact all nets of a YAWL specification along with all tasks that require interaction with the external environment need a decomposition Decompositions can have a number of parameters or variables defined for them describing what data must be supplied to a running net or task instance and what data that net or task instance will eventually deliver Each parameter has a name it may be referenced by a type dictating valid values it may store a designation indicating how that data may be use
289. tallation Package The Worklet Service is distributed as a standard component of the YAWL environment and so is included in each of the various installer packages and the YAWL2 0_CoreWebServices zip file used for manual installations Specifically the service is contained in the file workletService war this is the worklet web application component When unpacked workletService war also contains the worklet repository a required set of directories where worklets and rules files are stored logs are written to and so on and a number of sample worklets and rule sets including all those discussed in this manual are located The structure of the repository is shown in Figure 7 1 26 G logs O rules gt rulesEditor CO selected O worklets Figure 7 1 Worklet Repository Folder Structure e The logs folder is where the Service writes certain log files during its operation In particular the eventLog csv file logs the key events of the service when database persistence is disabled All are plain text files e The rules folder contains the sets of rules used during the selection and exception handling processes Rules files have an XML format Each YAWL specification that uses the service will have a correspond ing rules file of the same name except with an extension of zrs XML rule set e The rulesEditor folder contains a tool that is used to manage and modify rule sets see Section 7 5 2 for a complete description of the Ru
290. te but generic data editing forms designed for maximum flexibility and that can display data parameters of any type However their generic look and feel may not be appropriate in all cases for example where an organisation has a standardised set of forms for their business processes and would like their web based forms to match that standard In such cases a Custom Form may be user defined and associated with a task by specifying a URL to the form At runtime for such a task the Resource Service will package up the task data and send it to the custom form for display and or editing depending on how the form has been defined On submission of the form by the user the data is extracted from the form by the Service and passed back to the task in the same manner as dynamic forms Custom forms may be built using any web based technology such as JSF Javascript NET PHP or any other browser based environment that can receive data use it to populate form fields update the data with user inputs and pass control back to the calling service To set a custom form for a task right click and select Set Custom Form then enter the absolute URI of the custom form see Figure 4 56 To remove a custom form association open the dialog and enter a blank URI i e remove the URI from the dialog and click OK is 3 Set Custom Form URI Custom Form URI http www myserver com for
291. te information produced Figure 8 7 When the key pair is ready you can export the certificate via Export Private Key s first signing certificate file as simple certificate file Figure 8 8 8 4 5 Using the Digital Signature Service First please make sure that you have copied the DigitalSignature war in your tomcat webapps folder In the simplest case of using the Digital signature service you will need at least three tasks Figure 8 9 The first task Fulfil Document is a user task that can contain any complex type of document i e a variable you want to be signed You can define your complex type in the Update Data Type Definition dialog of the Editor as the example in Figure 8 10 The second task Sign Document redirects the user to a custom form which is located inside the DigitalSig nature war deployment We use a custom form to directly deal with the user instead of a standard custom service because private data like the key store password needs to be hidden from YAWL as the data is passed from one task to another as a net variable which is accessible by any other task You can define the Custom Form URI for the task by right clicking on the task in the Editor choosing Set Custom Form from the menu and then entering the URI of the form in the dialog shown Figure 8 11 You also have to define the task data that will be used by the custom form In this example their names should be Document
292. the correct location e Specification Paths the path or paths to locations on the local computer where YAWL specification files may be found The rules editor will search each of the paths provided for specifications for which rule sets may be created Multiple paths can be provided separated by semicolons e YAWL Editor the path and filename for the YAWL Editor Ss Co nfigure Paths Worklet Service URI http localhost 8080 workletService Worklet Repository CAworkletsvepositoy By Specification Paths CAyawhSpecsDMbin 000 YAW L Editor C yavleditary 4 LE ditort 4 jar m ro Figure 7 14 The Rules Editor Configuration Dialog 160 CHAPTER 7 THE WORKLET SERVICE Some checks will take place to make sure the paths are valid and you will be asked to correct any that are not Once the configuration is complete the main screen will appear This screen allows you to view each node of each rule tree defined for a particular specification From this screen you can also add new rules to the current rule set create new tree sets for an existing rule set and create entirely new rule sets for new specifications 7 5 3 Browsing an Existing Rule Set To load a rule set into the Rules Editor click on the File menu then select Open or click on the Open toolbar button The File Open Dialog will open with the rules folder of the repository selected Select the file you wish to open and then click OK Figure 7
293. the user and or those variables that the user will supply values for to be passed back to the parent task when the worklet completes e The definition of variables is not restricted to those defined in the parent task Any additional variables required for the operation of the worklet may also be defined here 152 CHAPTER 7 THE WORKLET SERVICE e Only those variables that have been defined with an identical name and data type to variables in the parent task and with a Usage of Input Only or Input amp Output will have data passed into them from the parent task when the worklet is launched e Only those variables that have been defined with an identical name and data type to variables in the parent task and with a Usage of Output Only or Input amp Output will pass their data values back to the parent task when the worklet completes In Figure 7 9 it can be seen that the values for the PatientID Name and Fever variables will be used by the TreatFever worklet as display only values the Notes Pharmacy and Treatment variables will receive values during the execution of the worklet and will map those values back to the top level Treat task when the worklet completes The association of tasks with the Worklet Service is not restricted to top level specifications Worklet specifications also may contain tasks that are associated with the Worklet Service and so may have worklets substituted for them so that a h
294. the left cf Figure 2 16 double click on the Postgres server and when prompted enter yawl as the password you should only be asked for this password the first time you connect Then right click on Databases under Postgres and choose New Database from the popup menu In the next dialog enter yawl as the database name leave all other fields as they are and click OK That completes the installation of postgreSQL and the admin tool pgAdmin and the creation of the YAWL database When YAWL is started it will automatically create the required database tables as part of its startup process 2 5 4 Configuring YAWL for other Databases YAWL uses Hibernate hibernate org as a database framework which provides a transparency layer between YAWL and the back end database used to support it While YAWL is pre configured to use Post ereSQL it is a relatively simple process to reconfigure for other databases Besides PostgreSQL YAWL has been successfully tested with MySQL HypersonicSQL Oracle and Apache Derby used by YAWL4Study but other database platforms are known to work with Hibernate see www hibernate org 80 html for the complete list and so should have no trouble working with YAWL too Each YAWL service that communicates with the database i e the Engine Resource Service and Worklet Service has a configuration file called hibernate properties located in its WEB INF classes directory The properties file contains a
295. the resource perspective The resource perspective of Business Process Management BPM is concerned with the way work is dis tributed to resources It is here that the link between the process model and the organisational model is formalised This is a very important perspective in BPM and one that has not had as much attention as the control flow perspective In fact the state of the art in BPM environments typically lacks sufficient support for the resource perspective consult the Workflow Patterns Home Page at www workflowpatterns com for more details The realisation of the resource perspective in YAWL 2 0 is based on the analysis work reported in a technical report on new YAWL 19 and Nick Russell s PhD thesis 20 This work formed the basis basis for the design and implementation of the resource perspective in YAWL 2 0 The Resource Service is a large custom service that contains a number of components primarily a Resource Manager that is responsible for the allocation of tasks to human users referred to as participants a Work list that comprise a series of web forms that provide a user interface to processes and process management Administration Tools that comprise a series of web forms to administer the Engine processes and organisa tional data a Dynamic Forms Generator which creates web forms on the fly for the presentation of work item data to participants so they can be performed and completed and a Codelet Co
296. the strategy for doing so Choose from one of the strategies below Choose the runtime allocation strategy Random Choice lt Back gt Next Finish Figure 4 52 Step 4 of the resource management wizard timer expires the task instance will complete no matter what its current status is offered allocated started The possible danger of this behaviour is that a work item might be timed out while being edited by a user in which case any modifications the user makes after that time are lost e In the case of an automated task the timer works as a delay i e the automatic execution of the task instance created by an automated task is delayed until the specified expiry time is not reached Once the timer expires the task is immediately executed and completed 4 11 2 Activation on starting e In case of a manual task the timer begins only when the task has started Therefore the task will be first offered then allocated and once it is started the timer starts Again the timer may expire while the task is being edited by a user e This option is does not apply for an automated task 4 11 3 Expiry value The expiry value of the timer specifies for how long the timer will live after being activated Expiry values can be expressed in either of two ways e Using a specific date and time which means the timer will expire at the specified moment To se
297. the timeout event and passes to the service a reference to itself and each of the other workitems that were running in parallel with the timed out item Therefore timeout rules may be defined for each of the workitems affected by the timeout including the actual time expired workitem itself ResourceU navailable This event occurs when an attempt has been made to allocate a workitem to a resource and the Resource Service reports that the resource is unavailable to accept the allocation ItemA bort An ItemAbort event occurs when a workitem being handled by an external program as opposed to a human user reports that the program has aborted before completion This event is not supported by this version of Exception Service Constraint Violation This event occurs when a data constraint has been violated for a workitem during execution as opposed to pre or post execution This event is not currently supported by the Exception Service 7 4 2 Exception Handling Primitives For any exception event that occurs a handling process may be invoked Each handling process called an exlet contains a number of steps or primitives in sequence and is defined graphically using the Worklet Rules Editor see Section 7 5 2 Each of the handling primitives is introduced below AL Suspend WorkItem suspends or pauses execution of a workitem until it is continued restarted cancelled failed or completed or its parent case is cancelled or completed
298. time which immediately become available for use in the service and the Editor For more information please consult the YAWL Technical Manual Since the Resource Service provides the default set of tools for user interaction with the YAWL system this chapter describes the runtime environment by describing the use of the service Configuration and Administration functionality is described first followed by the various user interactions 6 1 Resource Service Configuration The Resource Service has a number of configuration parameters that may be set in the service s web xml file which is located in the folder webapps resourceService WEB INF Below is the list of available parameters that are specific to the Resource Service what they are used for and what values may be assigned to them e EnablePersistence When set to true default allows the service to persist backup current work queue data to a database so that in the event of the Engine being restarted the work in progress can be restored There is rarely any need to disable persistence and in any case this setting should match the EnablePersistence settings of the Engine and the Worklet Service e OrgDataSource While the Resource Service offers an internal organisational database by default it also supports organisational data being used that is stored in existing external data sources This is especially beneficial for sites that want to use org data already
299. ting application infrastructure to better support the day to day operations of the organisation BPM initiatives often translate into requirements for IT systems Here is where workflow technology comes into play Business process models produced by business experts are taken as a starting point by software architects to produce a blueprint for a software application that co ordinates monitors and controls some or all of the tasks that make up these business processes Such software applications are called workflows An example of a business process is an order to cash process one that goes from the moment a purchase order for a product or service is received by an organisation to the moment the customer pays for the products including aspects such as invoicing and shipment After capturing this process from beginning to end an organisation may choose to add further details about the people legacy applications messages and documents involved and to deploy a workflow application to co ordinate this process You can build a workflow application using general purpose software programming platforms e g as a bunch of Web applications Enterprise Java Beans and legacy applications connected together but this defeats the purpose of aligning the models produced by business people with the resulting IT systems This is why one should consider an alternative approach to develop workflow applications on top of a dedicated workflow management system M
300. tion path and port numbers see figure 2 7 of Apache Tomcat are set The default port numbers are fine in most cases and only need to be changed if those ports are already in use The YAWL4Enterprise installer allows to install a supplied version of PostgreSQL or to use an already installed PostgreSQL or MySQL version see figure 2 8 3http sourceforge net forum forum php forum_id 391803 http sourceforge net projects yawl 2 3 YAWL4ENTERPRISE 15 Tomcat Configuration vt seak net gt cancel Figure 2 7 Set up of Tomcat Ports Database Choice xd Install PostgreSQL 8 3 and YAWL DB Install PostgreSQL 8 3 and YAWL DB Use existing PostgreSQL Use existing MySQL SOL i ane Figure 2 8 Specification of Database If you choose to install PostgreSQL and the YAWL DB the PostgreSQL installation directory and different PostgreSQL settings can be specified see figure 2 9 Again the default settings are suitable in most cases Database Settings v Figure 2 9 Specification of PostgreSQL settings The last installation panel allows specifying whether Apache Tomcat and or PostgreSQL should run as services 16 CHAPTER 2 INSTALLATION 2 4 YAWLive The release package on the YAWL project web page on sourceforge provides an iso image with a complete operating system and preconfigured YAWL environment The advantage of using YAWLive is that it can be used within a virtual machine
301. ts 12 56 08 140 DEBUG ES Invoking exception handling process for item 20 DoShow_4 12 56 08 156 DEBUG ES Exception process step 1 Action suspend Target workitem 12 56 08 171 DEBUG ES Successful work item suspend 20 DoShow_4 12 56 08 203 DEBUG ES Exception process step 2 Action compensate Target ChangeToMid Venue 12 56 08 343 DEBUG WS Worklet specification ChangeToMid Venue is already loaded in Engine 12 56 08 546 DEBUG WS Launched case for worklet ChangeToMidVenue with ID 21 12 56 08 578 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 56 08 593 INFO ES Checking post constraints for workitem 20 2 Sell Tickets_3 12 56 08 593 INFO ES No post task constraints defined for task SellTickets 12 56 08 593 INFO ES HANDLE CHECK CASE CONSTRAINT EVENT 12 56 08 593 INFO ES Checking constraints for start of case 21 of specification ChangeToMidVenue 12 56 08 609 INFO ES No pre case constraints defined for spec Change ToMid Venue 12 56 08 609 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 12 56 08 640 INFO ES Checking pre constraints for workitem 21 CancelStadium_3 12 56 08 656 INFO ES No pre task constraints defined fortask CancelStadium 13 02 48 171 INFO ES HANDLE CHECK WORKITEM CONSTRAINT EVENT 13 02 48 187 INFO ES Checking pre constraints for workitem 21 Book_Ent_Centre_5 13 02 48 234 INFO ES No pre task constraints defined for task Book_Ent
302. ts and so on referred to in this manual can be found in the worklet repository distributed with the service as part of the YAWL 2 0 release This icon indicates a hands on method or instruction 7 1 What is a Custom YAWL Service An important point of extensibility of the YAWL system is its support for interconnecting external appli cations and services with the workflow execution engine using a service oriented approach This enables running workflow instances and external applications to interact with each other in order to delegate work to signal the creation of process instances and workitems or to notify a certain event or a change of status of existing workitems Custom YAWL services are external applications that interact with the YAWL engine through XML HTTP messages via certain endpoints some located on the YAWL engine side and others on the service side Custom YAWL services are registered with the YAWL engine by specifying their location in the form of a base URL Once registered a custom service may send and receive XML messages to and from the engine More specifically Custom YAWL services are able to check out and check in workitems from the YAWL engine They receive a message when an item is enabled and therefore can be checked out When the Custom YAWL service is finished with the item it can check it back in in which case the engine will set the work item to be completed and proceed with the execution 7 1
303. ts chosen will be launched concurrently and the process will continue only after all the worklets launched have completed 7 0 WORKLET RULE SETS AND THE RULES EDITOR 165 E Choose Worklet w orklet BobfFive BobFour Bobne BobT hree BobT wo Bobero Cancellrder Cancels how Cancel est Casualty Treatment Casualty Treatment w Change oLangerenue Change T oMidy enue Change oS mallvenue Multi est Urganigeloncert New Figure 7 19 The Choose Worklet dialog When the new worklet is saved and the YAWL Editor is closed the name of the newly created worklet will be displayed and selected in the worklet drop down list Click the OK button to confirm the selection and close the dialog Figure 7 20 shows the New Rule Node panel after the definition of the example new rule has been completed A value in the Description field is optional but recommended Hew Aule Node Mode ID 10 Parent Node ID E Condition HeartRate gt 175 Conclusion 1 select TreatHighHeartA ate Description worklet i used to treat patients with very high heart rates Figure 7 20 The New Rule Node Panel after a New Rule has been Defined Once all the fields for the new rule are complete and valid click the Save button to add the new rule to the rule tree 7 5 6 Dynamic Replacement of an Executing Worklet Remember that the creation of this new rule was triggered by the selection and execution of a worklet that was deemed an inappr
304. u to build a sequence of tasks or primitives in an exception handling process explained in detail below When the conclusion sequence has been defined and the dialog closed a text based version of it will display in the Conclusion panel Once the new rule node has a valid condition and conclusion and optionally some cornerstone data and a description click the Add Rule button to add the rule to the tree The new node will be displayed at the selected position on the tree with the relevant coloured node icon indicating whether it is a true or false node of its parent New potential node add points will also be displayed See Figure 7 26 for an example of a newly created tree that has several nodes added Repeat the add rule procedure for however many rule nodes you wish to add by clicking on the appropriate yellow node note that when you click on a node other than yellow its stored details are displayed in the various form inputs TIPS e If the number of nodes starts to get a little confusing you can check which node is the parent of the selected node by looking at its id in the Selected Node panel 170 CHAPTER 7 THE WORKLET SERVICE AOR Tree New True Rule Rule 3 C New True Rule B Rule 4 8 Rule 5 C Hew True Rule 0 New False Rule New False Rule r New False Rule Figure 7 26 Creating a New Rule Tree e If you start to add details for a new node then change your mind about adding it simply clic
305. udy A A long running workflows YAWL4Enterprise v v Long running workflows YAWLive Medium A Y SANGYO MINIMA persistence possible Figure 2 1 YAWL product comparison Official and stable versions of the YAWL installation files are found on the YAWL project web page on sourceforge under Download release package YAWL Complete lhttp downloads sourceforge net yawl right yawl version for YOU pdf 2http sourceforge net projects yawl 11 12 CHAPTER 2 INSTALLATION 2 1 Requirements Pre requisites depend on the type of installation used YAW Live distributed as an iso image is a complete OS and pre installed YAWL package that will run on any computer that can load it in a virtual machine e g VirtualBox or VMware While the image can be burned to a CD and booted from there some hardware configurations may experience a freeze during boot phase All other installation types require the Java SE Runtime Environment JRE 1 5 or greater java sun com YAWLA4Study for Linux requires installed xdg utils portland freedesktop org which should be sup ported by your desktop environment GNOME and KDE do support xdg utils in order to visualise YAWL Editor menu entries YAWL 2 0 has been successfully tested on e Windows XP Vista Windows 7 beta Server e Linux Ubuntu 8 10 sidux Debian Etch e Mac OSX Tiger Leopard 2 2 YAWLA4AStudy The release package provides installation files for the operating syste
306. ule panel displays a properly indented text equivalent of the composite condition comprising the conditions of the selected node and all ancestor nodes back to the root node in other words the entire composite condition that must evaluate to true for the conclusion of the selected node to be returned e The RDR Tree panel dynamically displays graphically the new rule tree as it is being created New rule nodes can be added wherever there is a node on the tree that does not have a child node on both its true and false branches except the root node which can have a true branch only To identify possible locations to add a rule node special potential nodes can be seen in the RDR Tree panel called New True Node or New False Node These potential nodes are coloured yellow for easy identification To add a new rule select the yellow new rule node where you would like the rule to be added When you select a new rule node the various inputs for the new rule become enabled Refer to the Adding a New Rule section above for details of the types of operands and operators you can add as the condition of the new rule To add a conclusion to the new rule click the New button If the currently selected rule type is Selection a worklet can be added as a conclusion in the way described in the Adding a New Rule section If it is one of the exception rule types the New button will display the graphical Draw Conclusion dialog allowing yo
307. unt that YAWL uses to connect to the database Leave the settings for all other screens at their defaults and click through to completion i PostereSQL Initlalig e database cluster W Initialize database cluster Fort number 5432 Addresses Locale Encoding Server lure eee oka Superuser name Password Password again NYA Accept connections on all addreses not just localhost cal suis This is the internal database username and not the service account For security reasons the password should WOT be the same as the service account Client Back Cancel Figure 2 15 Keep postgres as the Superuser name and enter yawl as the password pgAdmin Ill AA Object browser y B Servers 1 gig sy M Properties Statistics Dependencies Dependents D Property E Description Hostname E Port PostgreSQL 8 3 localhost 5432 Username f Connected Maintenance database Store password Restore environment Value PostgreSQL 8 3 localhost 5432 postgres postgres No No No oS jap SQL pane a9 jal Retrieving Server details Done 0 06 secs 4 Figure 2 16 The pgAdmin tool Object Browser panel on the left Next run the administration tool pgAdmin which was installed along with the postgreSQL installation Cwww pgadmin org 2 5 MANUAL INSTALLATION 21 In the Object Browser panel on
308. urchase Order tae A lt i Lil A E http localhost 8080 resourceService faci Go ict Users Org Data Services Browse ations Order Fulfilment process model Unload Spec Use the palette toolbar to edit the selected net DSL e YAWLEditor ramdisk home dsi orderfulflment yawl X YAWL 2 0 Case Management Mozilla Firefox 07 55 PM OH Right Ctrl Figure 2 12 YAWLive Desktop with Editor and Worklist running 18 CHAPTER 2 INSTALLATION For installation on Mac OSX follow the instructions at wiki apache org tomcat TomcatOnMacOS Ignore the first half of the page start from the heading Updated for 2006 The steps for starting the firewall and enabling port forwarding are not required from a YAWL perspective Linux installation is quite straightforward A simple set of instructions for ubuntu can be found at www howtogeek com howto linux installing tomcat 6 on ubuntu In all cases an environment variable called CATALINA HOME needs to be added which points to the tomcat install path Once Tomcat is installed two small configuration changes are required to files found in the lt your_tomcat_dir gt conf directory 6697 1 context xml Locate the commented line containing lt Manager pathname gt and uncomment it 2 server xml Locate the entry that begins lt Connector port 8080 protocol HTTP
309. ure 4 20 A Cancellation Set specified for the Order from Amazon task Notes about Cancellation Sets In the example in Figure 4 20 notice that there is an AND split decorating the Get Book Details task but the Pay task has an XOR join This is because we know that when one of the Order tasks completes the other two will be cancelled so only one incoming flow to the Pay task will activate Since we want the process to complete we must add the join type that will activate the task when a single incoming flow activates the XOR join If an AND join had been used here it would wait until all three incoming flows were activated which in this case is never going to happen and would result in the deadlock of the workflow instance A Cancellation Set that has been created will remain in the specification regardless of whether you have the View Cancellation Set option ticked You can create multiple Cancellation Sets in your workflow by selecting another task and choosing the View Cancellation Set option Only one cancellation set may be viewed at any one time All flows leading to or from explicit conditions are not valid cancellation set members Neither are the Input and Output conditions The editor will ignore them if you select them for inclusion in a task s cancellation set A task may be included as a member of its own cancellation set 62 CHAPTER 4 THE EDITOR e The reason for including preceding fl
310. ure 6 12 On the left is a list of the work items currently held in that queue In the centre are some fields that describe the currently selected work item On the right are a set of buttons representing the actions that may or may not be taken depending on privileges on that queue for the currently selected work item Each work queue may be selected by clicking on the appropriate tab 6 4 WORK QUEUES 133 Suspended Accept amp Start Dealiocate Reallocate Allocated Completed Complete Figure 6 11 Part of the Life cycle of a Work Item 6 4 1 The Offered Queue The Offered queue lists the work items that have been offered to a participant Each work item in an offered queue may have potentially been offered to a number of participants which means there is no implied obligation to accept the offer rather it is understood that the participant is one of a group any one of who may choose to perform the work item Work Items 2 1 Create_Purchase_Order_104 54 Create_Book_List_4 Status Enabled Age Jul 23 2009 15 22 11 0 0001 14 Figure 6 12 The Offered Work Queue A participant may take the following actions on a work item in an offered queue e Accept Offer By accepting an offer a participant takes responsibility for the execution of the work item The work item is moved from the offered queue and if the start interaction is user initiated placed on the participant s allocated
311. vate Study will be followed XOR Split How that choice is made will be explained a little later Get a Job will become available after the completion of the task selected at the point of the XOR split Composite Tasks 1 Composite tasks are placeholders for other sub nets That is you can create another workflow in a separate Net which is represented in the first net by the composite task When a composite task is activated control branches to the sub net when the sub net completes control passes back to the parent net To create a Composite Task click on the Composite Task button o in the Elements panel or right click on an empty part of the canvas and choose Composite Task We are going to replace our existing Go to University Atomic Task with a Composite Task so click on the Go to University Atomic Task and click the trash bin on the toolbar or press the Delete key on the keyboard We will add in the new composite task next 4 3 CREATING YOUR FIRST SPECIFICATION ol Place your Composite Task in your Net Tip use the arrow keys on your keyboard to move adjust the task to the desired location Reconnect the Flow Relations from Begin My Career to the new Composite Task and from new Composite Task to Get a Job Create a new Net by clicking on the Create a New Net button E on the Menu Toolbar or click on the Net Menu and choose Create Net Choose a name for this Net by
312. vided on a form using a digital signature via X 509 certificates and private keys 3 mailSender war provides a custom form for a task from which an email can be sent Tip If a war file is to be copied into the webapps directory to replace a file of the same name it is advisable to first shutdown Tomcat and delete the unpacked directory for that war before copying in the new war file On restart the new war s contents will be unpacked If the old unpacked directory is not removed on restart the new war file will not unpack If Tomcat is running when the new war is copied to the webapps directory it will unpack and replace the old directory but may run out of resources while doing so resulting in an OutOfMemoryError 2 5 MANUAL INSTALLATION F T apache tomecat 5 5 25 T apache tomcat 6 0 18 gt logs bin gt conf I lib EE LICENSE G logs EE NOTICE EE RELEASE NOTES RUNNING txt T temp gt webapps 19 T docs E examples E host manager js manager T resourceService f resourceService war i ROOT T workletService workletService war T yawl T work r yawl war T yawlWsSInvoker yawlWSinvoker war a an F Figure 2 13 YAWL Core Services deployed in webapps directory OSX Example 2 5 3 Installing PostgreSQL As a default YAWL is configured to use PostgreSQL for database support and this section describes how to manually install and configure PostgreSQL for Y
313. whether to book a flight hotel and or car as alternative to the previous example we group these needs together this time Figure 5 22 shows the net variable definitions for the make trip net There are three new variables itinerary legs and subTotals as compared to the previous simple Make Trip Process net in Section 5 5 2 Figure 5 23 shows the parameter definition of task register There are three task variables customer legs and payAccNumber with appropriate input or output parameter definition Figure 5 24 shows the parameter definition of task pay There are four variables which are all input only variables Note the input parameter definition of the mapping from variable subTotal to variable total The XQuery function sum calculates a total sum of subTotals from each itinerary segment Figure 5 25 shows the parameter definition of the multiple instance composite task do itinerary segment There are nine task variables which are also the net variables of the subnet of this task All except startDate 5 5 ILLUSTRATIVE EXAMPLES 113 A Update Data Type Definitions xei schena xnlns xs http iy ws org 2001 MLoichena gt lt xeicomplexType name itinerarylype gt lt x gequence gt x5r elenent name 1tineraryseqment type 1tineraryseq ype minUecurs 1 maxO0ccurs unbounded gt eS Sequence gt x3 conplexType gt xe complexType name i1tineraryseqType gt EG
314. while instances are running So rather than being forced to define all possible branches in a specification when it is first defined the Worklet Service allows you to define a much simpler specification that will evolve dynamically as more worklets are added to the repertoire for a particular task as different contexts arise The first thing you need to do to make use of the service is to create a number of YAWL specifications one which will act as the top level or manager or parent specification and one or more worklets which will be dynamically substituted for particular top level tasks at runtime The YAWL Editor is used to create both top level and worklet specifications A knowledge of creating and 7 3 USING THE WORKLET SELECTION SERVICE 149 editing YAWL specifications and the definition of data variables and parameters for tasks and specifications is assumed For more information on how to use the YAWL Editor see Chapter 4 Before opening the YAWL Editor make sure that the Worklet Service is correctly installed and that Tomcat is running see Section 7 2 of this chapter and or Chapter 2 for more information First a top level specification needs to be defined 7 3 1 Top level or Parent Specifications To define a top level specification open the YAWL Editor and create a process specification in the usual manner Choose one or more tasks in the specification that you want to have replaced with a worklet at runtim
315. work on that data and finally return work results to YAWL Another type of decomposition which we won t illustrate in this tutorial is to associate tasks to a Web Service that can for example send notifications to 28 CHAPTER 3 GETTING STARTED WITH YAWL Name Symbor aor er Types XOR Split AND Split OR Split Join Types The XOR Split is used to trigger only one outgoing flow It is best used for automatically choosing between a number of possible exclusive alternatives once a task completes The AND Split is used to start a number of task instances simul taneously It can be viewed as a specialisation of the OR Split where work will be triggered to start on all outgoing flows The OR Split is used to trigger some but not necessarily all outgo ing flows to other tasks It is best used when we won t know until run time exactly what concurrent resultant work can lead from the completion of a task all of its incoming flows before beginning It is typically used to synchronise pre requisite activities that must be completed before some new piece of work may begin AND Join XOR Join people via SMS and receive replies from them also via SMS Once any work has completed on an incoming flow a task with an XOR Join will be capable of beginning work It is typically used to allow new work to start so long as one of several different pieces of earlier work have been completed The OR Join ensures that a tas
316. y Figure 4 7 Task Indicators The three task indicators left to right in Figure 4 7 are 4 3 CREATING YOUR FIRST SPECIFICATION 49 e Timer This task has had a timer set see Section 4 11 e Automated This task has been set as automated see Section 4 9 If this automated task also has a codelet specified it will be filled green see Section 4 9 1 e Cancellation Set This task has had a cancellation set defined see Section 4 5 1 These task indicators are rendered on top of any icons set for the task Task Decoration Decorating a task is the process of adding a split and or join to the task By adding a split decorator to a task you are specifying that when the task completes it will be succeeded by one or more tasks Here are the possible choices for a task s split decorator e No split The task has no split decorator and so will have exactly one outgoing flow e AND split The task may have a number of outgoing flows when the task completes it will activate each and every outgoing flow e XOR split The task may have a number of outgoing flows each with an associated condition when the task completes it will activate exactly one outgoing flow the first that has its condition evaluate to true or the designated default flow if none of the other flow conditions evaluate to true e OR split The task may have a number of outgoing flows each with an associated condition when the task completes
317. y IP related to YAWL and its support environment 1 4 Documentation Apart from this user manual there is a technical manual on YAWL and a number of case studies These studies provide detailed examples that you may wish to consult in order to obtain a deeper understanding of the application of YAWL This manual does not really cover the control flow concepts of YAWL in detail One reason for this is that there are quite a few papers out there that do provide this information We refer the reader to e g 5 for a justification of the extensions of Petri nets introduced for YAWL on the basis of the original control flow patterns The main paper on YAWL from a language point of view is 6 In this paper you find a formalisation of the control flow concepts of YAWL More recently a CPN formalisation of newYAWL control flow data and resource perspectives was presented in 20 For a formalisation of the OR join a complex synchronisation concept in YAWL we refer to 24 This definition supersedes the definition provided in 6 As mentioned above YAWL extends Petri nets There are a number of general introductions to Petri nets in the literature We refer the interested reader to 14 12 1 4 DOCUMENTATION 9 Wil van der Aalst has written much about the application of Petri nets to workflow see e g 1 The subclass of Petri nets introduced by him Workflow nets is a predecessor of YAWL The textbook that he wrote together wit

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