The CAS server – User Manual
Contents
1. lt ELEMENT machineid CDATA gt lt ELEMENT cpupower CDATA gt lt ELEMENT availcpupower CDATA gt lt ELEMENT processornr CDATA gt lt ELEMENT totalram CDATA gt lt ELEMENT availram CDATA gt lt ELEMENT availdisk CDATA gt lt ELEMENT cas casid machineref casname casactive casdescription casexample updated gt lt ELEMENT casid CDATA gt lt ELEMENT machineref CDATA gt lt ELEMENT casname CDATA gt lt ELEMENT casactive CDATA gt lt ELEMENT casdescription CDATA gt lt ELEMENT casexample CDATA gt lt ELEMENT updated CDATA gt lt ELEMENT method methodid methodname methodpackage methodsignature methoddescription gt lt ELEMENT methodid CDATA gt lt ELEMENT methodname CDATA gt lt ELEMENT methodpackage CDATA gt lt ELEMENT methodsignature CDATA gt lt ELEMENT methoddescription CDATA gt lt ELEMENT symbol symbolid symbolname symbolcdid symbolcdcdid symboldescription updated gt lt ELEMENT symbolid CDATA gt lt ELEMENT symbolname CDATA gt lt ELEMENT symbolcdid CDATA gt lt ELEMENT symbolcdcdid CDATA gt lt ELEMENT symboldescription CDATA gt lt ELEMENT updated CDATA gt S2. An example of a valid response message that is sent when the resolve process ended successfully is lt symbolmessage gt lt symbol gt lt name gt symboll lt name gt lt cd gt cd_of_symbol1l lt cd gt lt symbol gt lt symbol gt lt name gt symbol2 lt name gt lt cd gt cd_of_symbo1l2 lt cd gt lt symbol gt lt reference gt http host com skipped_ref document id lt reference gt lt symbolmessage gt The above response message specifies that the server found the OpenMath symbols symboll cd_of_symbol1 and symbol2 cd_of_symbol2 and encountered a reference that was in the scope of a parent resolver http host com skipped_ref document id which the resolver did not attempt to solve An example of a valid response message that is sent when the resolve process ended with an error is lt symbolmessage gt lt error gt Error message lt error gt lt symbolmessage gt The above response message specifies that the resolve process ended with the error co Brror message SClEnce leAt Team 11 The CAS server User Manual 4 2 3 Service Interfaces Participating in Target Node Retrieval Before starting to execute a call described based on OpenMath objects all the required objects must be available for the executing CAS Since CASs are not in general able to contact remote hosts to obtain objects that are not hosted on the execution machine the CAS Server implements
3. SWIP_startSequence aVarl SWIP_invoke GAP Int n 1 Sn SWIP_startMultiChoice SWIP_startChoiceBranch Sn lt 10 SWIP_invoke GAP Int n 1 Sn SWIP_endChoiceBranch SWIP_endMultiChoice SWIP_endSequence SWIP_endWhile SWIP_endWorkflow SWIP_readOutput SWIP_processHandler Another complete example for the creation of a simple workflow is given in the next code snippet SClEnce leAt Team 27 The CAS server User Manual LoadPackage SWIP SWIP_startWorkflow SWIP_declareVariable i 0 SWIP_startSequence SWIP_invoke GAP Int 1000 300 SWIP_startWhile Si lt 5 SWIP_invoke GAP increment i i SWIP_endWhile SWIP_endSequence SWIP_startForeach 1 5 SWIP_startParallel SWIP_invoke Kant GCD 1234 5678 SWIP_invoke Maple gcd 1234 5678 SWIP_endParallel SWIP_endForeach SWIP_endWorkflow SWIP_readOutput SWIP_processHandler The previous GAP code produces the following workflow in the proposed abstract language lt workflow xmlns http www ieat ro gt lt sequence gt lt invoke uniqueID invoke_1 gt lt casID gt GAP lt casID gt lt call gt Int 1000 300 lt call gt lt invoke gt lt variable name variable_1 gt 0 lt variable gt lt while gt lt condition gt Svariable_1 amp lt 5 lt condition gt lt invoke uniqueID invoke_2 gt lt variable gt Svariable_1 lt
4. taVarl 4 aVar2 us where represents here the concatenation operator It must be noted that all variable names that appear within the condition must be preceded by the special character Thus a variable name aVariable will appear within the condition string as aVariable The condition should be a string that can be evaluated to a boolean value The expression may be formed using numerical values comparison operators and variable names SWIP_startWorkflow Functionality This function is used to mark the beginning of a workflow description Every workflow should start by calling this function The function may only be called once to start the workflow description Multiple redundant calls of this function will result in an error The function returns a unique identifier of the current workflow that is later used by the client to get the result of the workflow s execution SClEnce leAt Team 18 The CAS server User Manual Implementation Remarks Implementation of this function must result in starting a new workflow document and adding the lt workflow gt tag to the document SWIP_endWorkflow Functionality This function is used to mark the end of a workflow description Every workflow definition should be marked by calling this function The function may only be called once in correspondence with a previous SWIP_startWorkflow call Multiple redundant calls of this function will
5. workflow SWIP_endMultiChoice Functionality This function is used to mark the end of a multichoice Implementation Remarks A call to this function should result in adding a lt multichoice gt tag to the document describing the workflow SWIP_startChoiceBranch Functionality The function SWIP_startChoiceBranch condition may be used to define a conditional execution within a multichoice container The SWIP_startChoiceBranch represents a marker for the start of the branch See also Remark regarding accepted condition format Implementation Remarks The call of that function should add to the workflow document a new choice branch construct tags Thus a new branch tag should be added and immediately after a node containing the conditional expression lt condition gt theCondition lt condition gt where the theCondition represents the actual condition that the user stated Note Here variable name refers to the name of the variable as it appears in the workflow document and not the name of the variable container that is used within the CAS to hold the name For additional information see the section explaining variable types and methods of declaring them SWIP_endChoiceBranch Functionality This function is used to mark the end of a multichoice branch Implementation Remarks A call to this function should result in adding a lt choice gt tag to the document describing the workflow Example GAP code
6. SWIP_startMultichoice SWIP_startChoiceBranch Concatenation 5 gt aVar SWIP_startChoiceBranch SWIP_endMultichoice XML Code lt choicebranch gt SClEnce leAt Team 21 The CAS server User Manual lt condition gt 5 amp gt Svariable_0 lt condition gt lt choicebranch gt SWIP _if Functionality The call to of SWIP_if condition function allows the user to start an if construct In the scope of the if construct an SWIP_trueBranch or a SWIP_trueBranch followed by an SWIP_elseBranch may appear The condition must meet the requirements stated by Remark Implementation Remarks The call to this function must add to the document an opening tag lt if gt that must be followed by a node lt condition gt theCondition lt condition gt that states the condition to be met and a starting tag lt truebranch gt For additional details see Remark1 SWIP_endlf Functionality This function is used to mark the end of the if construct Implementation Remarks A call to this function should result in adding a lt truebranch gt closing tag if the if construct does not contain an else branch a lt elsebranch gt if the if construct contains an else branch and a final lt if gt tag to the document describing the workflow SWIP_else Functionality The call to the function SW P_else result in marking a code section that is executed if the condition specified with the SWIP_if call is not m
7. ELEMENT casinfo casserver cas gt lt ELEMENT casserver CDATA gt lt ELEMENT cas CDATA gt lt ELEMENT function functionname functionsignature Functionpackage functiondescription gt lt ELEMENT functionname CDATA gt lt ELEMENT functionsignature CDATA gt lt ELEMENT functionpackage CDATA gt lt ELEMENT functiondescription CDATA gt The structure of the getCASsSupportingFunction operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT cass cast gt lt ELEMENT cas casserverurl casname casdescription casexample cascanpause cpupower availablecpupower nrofprocessors totalram availableram availablediskspace gt casserverurl CDATA gt casname CDATA gt casdescription CDATA gt casexample CDATA gt cascanpause CDATA gt availablecpupower CDATA gt nrofprocessors CDATA gt totalram CDATA gt availableram CDATA gt availablediskspace CDATA gt lt ELE lt ELE lt ELE lt ELE lt ELE lt ELE lt ELE lt ELE lt ELE S lt SSS SES SESE ZABZABAZABAABAA The structure of the getCASsSupportingSymbol operation s response The string returned by invoking the operat
8. SClEnce leAt Team 6 The CAS server User Manual The structure of the getSupportedSymbolsoperation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT cassymbols casname symbol gt lt ELEMENT casname CDATA gt lt ELEMENT symbol symbolname symbolcd symboldescription gt lt ELEMENT symbolname CDATA gt lt ELEMENT symbolcd CDATA gt lt ELEMENT symboldescription CDATA gt 4 1 1 Submitting a New Task and Task Management SCSCP Call Remote Function Call Remote function call is an alternative to standard SCSP call supplied for commodity reasons This type of invocation may be useful if the target CAS does not implement the SCSCP protocol and does not have built in support for OpenMath Usually such CAS instances may be started as a separate process and the required interaction with the process may be carried out through the standard input output streams In this situation using the CAS functionality is similar to direct interaction through the command line interface of the CAS The CAS Server acts as a communication bridge between the remote client and the CASs installed on the local machine The correct formulated call must comply with the following DTD structure lt ELEMEN
9. should register the adding the new CAS and not by changing the name of the CAS from GAP1 to GAP2 in the Local Registry Administrator With the latter approach taken the information in the database will be inconsistent and for all tasks that were run on the GAP1 instance the system will indicate that they were run on the GAP2 instance 4 3 1 Changes update message structure SClEnce leAt Team 14 The CAS server User Manual The update message send by the CAS Server to a certain registry contains only those pieces of information that are relevant for the registry to which the update is sent It contains details regarding the CASs symbols and functions that are related to the registry and that were updated since the last successful update The interface of the Web service through with the discovery registry accepts update from CAS Servers must have the following signature updateRegistryInfo String CASServerURL String updateMessage where the CASServerURL represents the URL address of the CAS Server sending the update message The updateMessage parameter must be an XML document having the following structure lt ELEMENT server machine cast method symbol casmethod cassymbol symbolcd gt lt ELEMENT machine machineid cpupower availcpupower processornr totalram availram availdisk gt
10. system the CAS Server is able to extract the list of OpenMath symbols used in the scope of the target OpenMath objects or to extract the targeted objects and store them in separate files for later retrieval by a client Retrieving the list of OpenMath symbols is important when a client has to decide if a certain CAS Server implements all the functionality that a certain object requires Storing extracted nodes in separate files allows the client to retrieve the targeted objects at execution time During the resolving process a request for the list of symbols or for the actual OpenMath objects may lead while parsing the targeted objects to discovery of references to documents hosted on the same machine or even on another machine In this situation the resolving process must recurrently search for targeted objects The resolver component of the CAS Server is responsible for contacting third party CAS Servers implementing the resolve specific operations In this situation a resolver chain is created Example Lets assume that CAS Server CS1 receives a call that contains the references CS1 OMRI that targets an OpenMath object hosted on a local document and CS1_OMR2 that targets a OpenMath object hosted by CAS Server CS2 We also assume that the object targeted by CS1 OMR2 contains the reference CS2_OMR1 that targets an object hosted by CAS Server CS3 The resolving remote invocation chain is thus CS1 CS2 CS3 The nature of the messages exchanged be
11. the abstract language Each function call helps to build the workflow in an incremental approach Thus invoking functions in this package does not result in immediate execution of the invocation but in adding corresponding activities to the workflow The resulted workflow is sent to the server only when the description is complete and the user has finished describing the problem The package that we describe here for GAP may be easily ported for other for other CASs that support either invoking external scripts or executables or have support for remote Web service invocations To give a more clear view of the functionality and how it can be ported to other CASs we provide sections with technical details that may aid an experienced user that wants to build support for our system Tag or tag sequence Generating CAS Function lt workflow gt SWIP_ startWorkflow lt workflow gt SWIP_endWorkflow lt sequence gt SWIP _ startSequence lt sequence gt SWIP_endSequence lt multichoice gt SWIP_ startMultiChoice lt multichoice gt SWIP_endMultiChoice lt branch gt SWIP_ startChoiceBranch condition lt branch gt SWIP_endChoiceBranch SClEnce leAt Team 16 The CAS server User Manual lt if gt SWIP_if condition lt Sif gt SWIP_endlIfQ lt trueBranch gt SWIP_if condition lt trueBranch gt SWIP_else lt falseBranch gt SWIP_else l
12. the actual targeted OpenMath objects Parameters requestID of type string represents an identifier of the request that was originally sent by the client unique both in the scope of the client and the CAS Server It may be used to pair the original request result of type string represents a well formed XML describing the response The structure of the parameter is detailed in the following sub section Returns nothing Fault OMRResolveFaultType requested errorMessage 4 2 4 Messages to Retrieve the Targeted Nodes At the moment of the execution all the objects referenced by an OpenMath reference and used in the initial call document or in a subsequent referenced object must be available locally The CAS executing the call should not and is not expected to contact remote machines to transfer the requested objects The OM Object Resolve Request The request message must be a plain string representing a well formed XML document having the structure described by the following DTD lt ELEMENT noderequest referenc Skipreference gt lt ELEMENT reference value newid gt lt ELEMENT valu CDATA gt lt ELEMENT newid CDATA gt SClEnce leAt Team 12 The CAS server User Manual lt ELEMENT skipreference CDATA gt The string value supplied as a text child for the lt value gt element should contain the reference U
13. A call to this function should add to the workflow document an lt invoke gt node with all the details of the invocation Several details must be filled in the invokelID attribute of the lt invoke gt node should be assigned a unique value invoke_N where N represents the order number of the current invoke 0 indexed a child node of the lt invoke gt node named lt variable gt if the SWIP_invoke function was called with the optional argument The lt variable gt node should contain a text node with the value stored in the varReference parameter a child node of the lt invoke gt node named lt casid gt It will contain a child text node with the ID of the CAS as it is registered in the Main Registry a child node of the lt invoke gt node named lt call gt It will contain a child text node with the actual call For the moment OpenMath is not fully supported by CASs so the function call is expected As the support for OpenMath is increasing the call will be an OpenMath object encoded in XML and converted to string i e the special characters like lt must be replaced with their reference according to the XML specification Example Assuming that aVar holds the handler variable_0 and the localGAP variable var is intended to store the handler to the variable containing the result of the invoke the GAP code var SWIP_invoke GAP Gcd 100 10 aVar translates into the XML Code lt invoke invokeI
14. At Team 13 The CAS server User Manual 4 3 Handling update messages from monitored CAS Servers revise The CAS Server may be integrated into a bigger architecture to which the CAS Server represents an execution node Automated election of execution nodes must be based on real time information that describes the capabilities and status of the execution nodes The interface of the CAS Server exposes operations that allow a remote client to find all these details In order to save communication effort a better approach is to allow CAS Servers to advertise only those changes that are relevant for a certain discovery registry usually hosted at the same location with the automated workflow engine When using Local Registry Administrator application changes made to CAS Server status are stored into a local database but they are not automatically advertised to the intended registries After the administrator operates all the changes in the CAS Server status he must activate the synchronization to remote registries explicitly This operation is achieved by selecting the Notify menu When the Notify menu item is selected specific messages are constructed and sent to the registries via Web services calls The remote registry the recipient of the update message must expose an operation that is ready to receive update messages from CAS Servers Based on the current status of the CAS Server and the actual information successfully
15. ClEnce leAt Team 15 The CAS server User Manual lt ELE 5 z casmethod casmethodcasid casmethodmethodid casmethodactive updated gt T casmethodcasid CDATA gt casmethodmethodid CDATA gt casmethodactive CDATA gt updated CDATA gt lt ELE lt IE iF lt IE iF lt IE iF SSS 8 2 72 2 o lt ELE 5 z cassymbol cassymbolcasid cassymbolsymbolid cassymbolactive updated gt T cassymbolcasid CDATA gt cassymbolsymbolid CDATA gt cassymbolactive CDATA gt updated CDATA gt lt ELE lt IE iF lt IE iF lt IE iF SSS 8 2 2 2 B lt ELEMENT symbolcd symbolcdcdid symbolcdname gt lt ELEMENT symbolcdcdid CDATA gt lt ELEMENT symbolcdname CDATA gt 5 The SWIP package for GAP The targeted audience of the current system is comprised of CAS users A set of wrapper functions for GAP grouped into the SWIP package allow the GAP user to create their desired workflows for solving specific mathematical problems The workflow declared indirectly by the user is an abstract workflow description using the functions provided by the GAP SWIP package The user does not have to specify exact details of the XML abstract language but only how the logical tasks are composed Each function is mapped on an XML construct of
16. D invoke_0O gt lt variable gt Svariable_0 lt variable gt lt casid gt GAP lt casid gt lt call gt Gcd 100 500 lt call gt lt invoke gt SWIP_startForeach Functionality This function is used to implement a variation of the while construct This construct will repeat the activities in the scope of the SWIP_startForeach initValue endValue for a number of times determined by the values of initValue and endValue The two values may be references to pre initialized variables that hold numerical values OpenMath values may not be used or they may represent string codifications of numerical values Implementation Remarks This function must add to the workflow document a lt foreach gt start tag and two child nodes lt initvalue gt and lt endvalue gt The initvalue and the endvalue must be copied to the document as text nodes of the lt initvalue gt and lt endvalue gt nodes SWIP_endForeach Functionality This function is used to mark the end of the forEach construct SClEnce leAt Team 25 The CAS server User Manual Implementation Remarks This function must add to the workflow document a closing lt foreach gt tag Example Assuming that locallInit and localEnd are GAP variables that contain either numerical values or handlers to variables previously declared the GAP code SWIP_startForeach localInit localEnd j SWIP_endForeach j translates to the XML Code lt foreach gt lt i
17. Identifier String invokeldentifier throws CASServerFaultType void cancelTask String clientIdentifier String invokeldentifier throws CASServerFaultType void resumeTask String clientIdentifier String invokeldentifier throws CASServerFaultType void setTaskResult String clientIdentifier String invokeldentifier String result throws CASServerFaultType SClEnce leAt Team 8 The CAS server User Manual TODO complete explanations 4 2 OpenMath Resolver Interface For simplicity clarity and efficiency reasons an OpenMath document may contain references to sections of the same document or even sections that are part of another document In fact the OpenMath object may be defined by reusing objects defined in the same or external document In order to understand correctly an OpenMath object a CAS using the described object must be able to parse any referenced object encountered The resolve operation must implement mechanisms that collect all referenced objects used in the description of the OpenMath object being parsed even if the resolve process must use calls to remote third party storage entities that are able to provide the referenced objects One of the functionalities implemented by the CAS Server is ability to act as OpenMath storage repositories The CAS Server implements two main functionalities Given a set of OpenMath references targeting OpenMath objects that are stored as XML documents in the CAS Servers file
18. RL that must be solved The newid value supplied as a text child of the lt newid gt element should be the identifier value that replaces the identifier part of initial reference In the reference http host com skipped_ref document id the target identifier id is replaced with the new identifier supplied in the request message This replacement is required in order to avoid identifier collision of identifiers since all objects retrieved by executing the resolver process will be at the end stored in the same OpenMath document As a consequence the client request should be formulated to make sure that identifier name collision is highly improbable The lt skipreference gt elements should be used to designate the root URLs that identify references that should be skipped by the server An example of a valid request message is lt noderequest gt lt reference gt lt value gt http hostl com path file idl lt value gt lt newid gt newidl lt newid gt lt reference gt lt skipreference gt http host com lt skipreference lt skipreference gt lt noderequest gt The above request message requests that http host1 com path file id1 should be resolved and the identifier of the target object should be replaced with the newidl value It also instructs the resolver to skip all references that begin with http host com The OM Object Resolve Response The request message must be a plain string re
19. T OMOBJ OMA gt lt ELEMENT OMA OMS OMSTR OMSTR OMSTR gt lt ELEMENT OMS CDATA gt lt ATTLIST OMS cd CDATA FIXED casalll gt lt ATTLIST OMS name CDATA FIXED procedure_call gt lt ELEMENT OMSTR CDATA gt An example of such call might be lt OMOBJ gt lt OMA gt lt OMS cd cascalll name procedure_call gt lt OMSTR gt gcd lt OMSTR gt lt OMSTR gt default lt OMSTR gt lt OMSTR gt 5 lt OMSTR gt lt OMSTR gt 20 lt OMSTR gt lt OMA gt lt OMOBJ gt The OMS tag and its fixed valued parameters mark that the call is a remote function invocation so the CAS Server is able to treat the call accordingly The first OMSTR tag contains the name of the function that must be called on the target CAS the second OMSTR designates the package where the function is implemented while the rest of the OMSTR tags represent the parameters that must be sent to the function Based on the given description the function call string is constructed the correct CAS is started in a new process and the call is sent to the process For the above described call the function call is gcd 5 20 SClEnce leAt Team 7 The CAS server User Manual Once the result was computed by the CAS it is read by the CAS Server and the result is sent back to the original client Since the CAS Server is not able to semantically understand the result it provides to the client the result as is in whichever format it was retur
20. The CAS server User Manual AGSSO Component User Manual 1 2 2 1 2 2 Contents MY Titrod ctio ssas aeae a EEEE nausea A 2 2 Inst llation Steps vac accsumcaceucesncesunensnsioeniadeecenmce scucusnceeusenerasuseneseionameasgecwiceatensarantwees 2 2 1 PLELSOUISILCS iviex sa consdentanwnestuatiouss seusteswaneescutansedtveawinasbreantduacesyatsancecsetinesnaiis 2 2 2 Package CONTIN as snecaaduinscitedssdivaastadenedi adccannsaasanpdiatexentstocciasisdacaasnnndeaadecannens 2 2 3 Installing the Pa a0 C8 inca caGvecatuieescasnencancndensesasiinevaancanennensducaccatixeatauten ucatecenas 3 2 44 AGSSO deployment as a service scccs dsm naccvessriciaeaucsavineatnnneecreninreienwiee 3 2 5 CAS Server COnfiguUratiOnS as cssossecuss ohvncenessacteuasslaseassieuse RR EEE E Eiaa 3 2 5 1 Configuration FILE TEV ISE rccsasvsadenecnnsesubaxeos deenvbeessasvecscsusmseataumidseuvincenuness 3 3 AGSSO Administration Application yx iccsscdiatecaiatiecnpaanndecastaieansaWdaiaieniacndsnedecassane 3 4 Interfaces of the AGSSO compomnent ccssssccssscssscssecessecssnsseccssacssnsseesseenes 3 4 1 AGSSO DISCOVEL Y MCL EACS sisirin aieia E E RE E E EE 3 4 1 1 Submitting a New Task and Task Management cccccesseeeseeeseeeeees 7 4 1 2 Execution Management Interface 0 0 0 cee ceecceesceeeeceteceeeeeeeeecsseenteeneees 8 AD OpenMath Resolver Interface siccxs iwascednadecaisdicinesennieresiinaxtaitioatenieaxssinieceanen 9 4 2 1 Service Interf
21. aces Participating in OpenMath Symbol List Retrieval 10 4 2 2 Messages for Retrieving the List of OpenMath Symbols ee 10 4 2 3 Service Interfaces Participating in Target Node Retrieval 00 12 4 2 4 Messages to Retrieve the Targeted Nodes ccccscccssceeeeeeeeetseenseeees 12 4 3 Handling update messages from monitored CAS Servers revise 14 4 3 1 Changes update message Structure cccceccessceeeeeseeeeeeceeeeeeeeeeseecaeenes 14 MTG OS anera sears ee 28 Introduction Installation Steps Prerequisites Package Content The software package for the AGSSO software component contains the current release of the CAS Server and a number of required libraries included in the package for the convenience of the user The main folder and files in the distribution are conf folder containing various configuration files SClEnce leAt Team 2 The CAS server User Manual 2 3 Installing the Packages 2 4 AGSSO deployment as a service 2 5 CAS Server Configurations 2 5 1 Configuration File revise 3 AGSSO Administration Application The Administrative application allows the administrator of the node where the CAS Server was installed to set properties that have a direct impact on the functionality of the CAS Server Successful exposure and advertising of the functionality implemented by the server must follow a sequence of steps 4 Interfaces of the AGSSO component 4 1 AGSSO Discover
22. ble to submit tasks to Any task part of a workflow that must be executed should match the capabilities of at least one CAS installed on a CAS Server that is part of the computational infrastructure String getInstalledCASs String CASServerURL returns the list of the CASs installed on the CAS Server String getAllSupportedSymbols Siing CASServerURL returns the list of supported OM Symbols by any CAS installed on the specified CAS Server The returned message contains the list of symbols supported by the specified CAS Server and for each symbol it contains the list of CASs that supports it String getAllSupportedFunctions String CASServerURL returns the list of functions supported by any CAS installed on the CAS Server with the supplied name The returned message contains the list of function supported by the specified CAS Server and for each function it contains the list of CASs that supports it SClEnce leAt Team 3 The CAS server User Manual String getCASsSupportingFunction Sting functionName String package returns the list of CAS and detail regarding the CAS that implements the function given as a parameters String getCASsSupportingSymbol Sting omSymbol String omcd returns the list of CASs that support the OM Symbols that have the name omSymbol and are part of the OM Cd omcd regardless the CAS Server implementing it The returned message contains information regarding the CAS hosting CAS Se
23. ces are solved or it may respond with an error message SClEnce leAt Team 10 The CAS server User Manual The OM Symbol Resolve Request The request message must be a plain string representing a well formed XML document having the structure described by the following DTD lt ELEMENT symbolrequest referencet skipreference gt lt ELEMENT reference CDATA gt lt ELEMENT skipreference CDATA gt An example of a valid message is lt symbolrequest gt lt reference gt http host1l com path file idl lt reference gt lt skipreference gt http host com lt skipreference gt lt symbolrequest gt The above request message specifies that the server should resolve the reference specified by the lt reference gt element All subsequent references that are in the scope of the host specified through the lt skipreference gt i e the references that begin with the string http host com should not be solved by the resolver The OM Symbol Resolve Response The response message must be a plain string representing a well formed XML document having the structure described by the following DTD lt ELEMENT symbolmessage symbol reference error gt lt ELEMENT symbol name cd gt lt ELEMENT name CDATA gt lt ELEMENT cd CDATA gt lt ELEMENT skipreference CDATA gt lt ELEMENT error CDATA gt
24. cified in the scope of the while construct are executed repeatedly as long as the condition is evaluated to the boolean true The condition must be expressed as to meet the requirements stated by Remark Implementation Remarks A call to this function should result in adding a lt while gt start tag that must be followed by a node lt condition gt theCondition lt condition gt that states the condition to be met The condition must be expressed as to meet the requirements stated by Remark1 SClEnce leAt Team 23 The CAS server User Manual SWIP_endWhile Functionality This function is used to mark the end of the while construct Implementation Remarks A call to this function should result in adding a lt while gt closing tag for the while construct Example GAP code SWIP_startWhile Concatenation 101 lt aVar SWIP_startWhile XML Code lt while gt lt condition gt 101 amp lt Svariable_1 lt condition gt lt while gt SWIP_invoke Functionality Invoking a remote service may be achieved by invoking the function SWIP_invoke CasID command varReference The CasID parameter is the identifier of the CAS that the user wants to use in solving the invoke Valid IDs may be obtained by querying the system that the workflow will be submitted to Examples of such IDs GAP KANT MAPLE etc The command parameter is actual call of the remote function as it is document
25. d to express conditions and may be modified by storing result of remote service invocations when they are provided as the third parameter of the SWIP_invoke function designed for CASs This kind of variables must be declared using the SWIP_declare Variable function The user does not provide de actual name of the variable as it is used by the workflow but provides the name of the variable that will contain the handler of the variable Declaring a variable will store the handler of the variable into a local variable of type string declared within the CAS This handler may be further used to specify valid conditions Valid conditions are expressions that can be evaluated to boolean values by a subset of rules defined by XPath standard The subset is for the moment limited to composing simple expressions that contain decimal numbers boolean and comparison operators grouping parentheses and variable handlers of expressed declared variables Examples of valid conditional expressions include though they may not make any sense in thin context s lt 4 1 gt variable 1 SClEnce leAt Team 17 The CAS server User Manual Note To obtain the second expression within the CAS the 1 gt string needs to be concatenated with a the value of a local variable that was previously assigned with the handler of a workflow variable Thus a call SWIP_declareVariable varName 1 results in declaring a new workflow variable a
26. e code First a simple example is used in order to demonstrate how composition over different CASs can be performed For this we use the following simple formula gcd DenominatorRat Bernoulli 1000 DenominatorRat Bernoulli 1200 The denominator of the two Bernoulli numbers will be computed in parallel using the GAP algebra system while the gcd will be determined using KANT The GAP code for this example is presented in the next code snippet LoadPackage SWIP SWIP_startWorkflow SWIP_startSequence SWIP_startParallel aVarl SWIP_invoke GAP DenominatorRat Bernoulli 1000 aVar2 SWIP_invoke GAP DenominatorRat Bernoulli 1200 SWIP_endParallel SWIP_invoke KANT GCD SaVarl aVarl SWIP_endSequence SWIP_endWorkflow SWIP_readOutput SWIP_processHandler The next example is the ring workflow Imagine a ring of services where each service accepts request from its left neighbour for example an integer n performs an action for example n n 1 and sends the new value of n to its right neighbour The test is started with the initial value n 0 and will be terminated by that service on which the parameter n will reach the prescribed upper bound By implementing the ring workflow example we illustrate how the system can be used to implement more complicated workflows LoadPackage SWIP SWIP_startWorkflow SWIP_declareVariable n 0 SWIP_startWhile Sn lt 10
27. e references to objects hosted on a higher grade server TODO complete with real life examples 4 2 1 Service Interfaces Participating in OpenMath Symbol List Retrieval Retrieving the list of OpenMath symbols that are used to describe a certain OpenMath object is important if the client needs to determine if a certain CAS is able to understand a call to solve An OpenMath call may be solved by a CAS Server only if it manages a CAS instance that is able to understand every symbol describing the call Obtaining the list of OpenMath symbols describing a call should be achieved by trying to obtain the list of symbols used in the call and every targeted object used within the call A correct approach is to group by target host the references encountered in the call and send a symbol resolve request for every target host At CAS Server level if parsing the referenced objects results in additional discovered references it is the responsibility of the CAS Server to contact other CAS Servers using the same interface described below The interface is compound of two operations getSymbolList used to submit to a CAS Server a request to resolve a list of references that are in the scope of the contacted CAS Server The references are in the scope of the CAS Server if the host used in the reference URLs matches the host of the CAS Server Parameters requestID of type string represents an identifier of the request unique both in the scope of t
28. ed by the system that exposes that function The optional varReference is the handler provide by a SWIP_declareVariable function As a result the variable identified by the handler stored in varReference will hold the numerical value obtained by invoking the remote command The numerical value is represented using a string encoding of the number The function returns a string representing a handler to a the variable that holds the OpenMath representation of the result obtained by invoking remotely the command It must be noted thus that a function call that has all three input parameters specified will be used to compute a numerical value The numerical value is stored within to variables in two different formats i e OpenMath encoding and plain string encoding each of them suited to be used as an input for another invoke or as a term in a conditional expression respectively Note The main difference between the variable reference returned by this function and the variable reference identified by varReference as stated by Remark is that the variable identified by the former contains an OpenMath representation of the result and the later contains only the numerical value An evaluation process consisting from converting the OpenMath value to a numerical value by extracting the numerical value from the OpenMath object is automatically done at the server side SClEnce leAt Team 24 The CAS server User Manual Implementation Remarks
29. enMath Symbols etc that can be used to formulate tasks execution worflows The structure of the getInstalledCASs operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT casservers serverurlt gt lt ELEMENT serverurl CDATA gt The structure of the getAllSupportedSymbols operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELE lt ELE lt ELE lt ELE lt ELE lt ELE symbolinfos symbolinfot gt T symbolinfo casinfot symbol gt T casinfo casserver cas gt T casserver CDATA gt cas CDATA gt symbol symbolname symbolcd symboldescription gt eee EEEE SClEnce leAt Team 4 The CAS server User Manual lt ELEMENT symbolname CDATA gt lt ELEMENT symbolcd CDATA gt lt ELEMENT symboldescription CDATA gt The structure of the getAllSupportedFunctions operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT functioninfos functioninfot gt lt ELEMENT functioninfo casinfot function gt lt
30. et Implementation Remarks The call to this function should result in adding a closing lt truebranch gt and an opening lt elsebranch gt tag to the document Example GAP code SWIP_if condition SWIP_else SWIP_endIf XML Code lt if gt lt condition gt 5 amp gt Svariable_0 lt condition gt lt truebranch gt SClEnce leAt Team 22 The CAS server User Manual lt truebranch gt lt elsebranch gt lt elsebranch gt lt if gt SWIP_startParallel Functionality This function is used to mark that the activities that main activities that are in the scope of the parallel section will be executed in parallel It must be noted that activities that are in the scope of a sequence section that is itself in the scope of a parallel section will be executed as a sequence Implementation Remarks A call to this function must add to the document a lt parallel gt starting tag SWIP_endParallel Functionality This function is used to mark the end of the parallel section Implementation Remarks A call to this function should add to the document a closing tag for the parallel section lt parallel gt Example GAP code SWIP_startParallel SWIP_startParallel XML Code lt parallel gt lt parallel gt SWIP_startWhile Functionality The function SWIP_startWhile condition marks the start of a while construct As expected all activities spe
31. he client and the CAS Server request of type string represents a well formed XML describing the request The structure of the parameter is detailed in the following sub section callbackURL of type string represents the URL of the service where the resolve response shall be sent Returns nothing Fault OMRResolveFaultType requested errorMessage putSymbolList used to accept resolve responses from third party CAS Servers to which previously submitted resolve requests to obtain the list of symbols have been sent This operation must also be implemented by any client regardless it is a CAS Server or a client that needs to resolve a list of references for the contained list of symbols Parameters requestID of type string represents an identifier of the request that was originally sent by the client unique both in the scope of the client and the CAS Server It may be used to pair the original request result of type string represents a well formed XML describing the response The structure of the parameter is detailed in the following sub section Returns nothing Fault OMRResolveFaultType requested errorMessage 4 2 2 Messages for Retrieving the List of OpenMath Symbols In order to obtain the list of symbols the client must call the correct CAS Server and supply the list of references that must be solved The contacted CAS Server will contact the client when the submitted references and subsequent referen
32. he client when a resume operation is called e RESUME enables the client to resume the execution of a task that was previously paused If the underlying CAS was actually able to pause it the execution is resumed If the result was obtained meanwhile the result is sent to the client e CANCEL enables the client to cancel a certain task The CAS Server acknowledgs the received cancel call and tries to stop the execution of the task Since the task was cancelled at client s will the CAS Server does not execute a call back call as it would normally do when a task is finished It is the client s responsibility to manage this situation at client side e EXPRESS RESULT SETING a task execution may require a big amount of computational resources and a long completion time Especially when the CAS Server is used as an execution unit integrated in a bigger architecture that is able to run computational workflows it may be useful to enable the client to assume a certain result for a task without really computing it If the result of the task is set by the client any result obtained by computing the task is discarded The express result set operation triggers also the call back through which the result is provided to the waiting client This behavior is useful especially when the CAS Server s client is a workflow management engine The operations on the interface that allow the above mentioned functionality are void pauseTask String client
33. ion of the service is an XML document with the following structure lt ELEMENT cass cast gt lt ELEMENT cas casserverurl casname casdescription casexample cascanpause cpupower availablecpupower nrofprocessors totalram availableram availablediskspace gt lt ELEMENT casserverurl CDATA gt lt ELEMENT casname CDATA gt lt ELEMENT casdescription CDATA gt SClEnce leAt Team 5 The CAS server User Manual lt ELEMENT casexample CDATA gt lt ELEMENT cascanpause CDATA gt lt ELEMENT availablecpupower CDATA gt lt ELEMENT nrofprocessors CDATA gt lt ELEMENT totalram CDATA gt lt ELEMENT availableram CDATA gt lt ELEMENT availablediskspace CDATA gt The structure of the getFunctionsMatch operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT functioninfos functioninfot gt lt ELEMENT functioninfo casinfot function gt lt ELEMENT casinfo casserver cas gt lt ELEMENT casserver CDATA gt lt ELEMENT cas CDATA gt lt ELEMENT function functionname functionsignature Functionpackage funct
34. iondescription gt lt ELEMENT functionname CDATA gt lt ELEMENT functionsignature CDATA gt lt ELEMENT functionpackage CDATA gt lt ELEMENT functiondescription CDATA gt The structure of the getSymbolsMatch operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT symbolinfos symbolinfot gt lt ELEMENT symbolinfo casinfot symbol gt lt ELEMENT casinfo casserver cas gt lt ELEMENT casserver CDATA gt lt ELEMENT cas CDATA gt lt ELEMENT symbol symbolname symbolcd symboldescription gt lt ELEMENT symbolname CDATA gt lt ELEMENT symbolcd CDATA gt lt ELEMENT symboldescription CDATA gt The structure of the getSupportedFunctions operation s response The string returned by invoking the operation of the service is an XML document with the following structure lt ELEMENT casfunctions casname functiont gt lt ELEMENT casname CDATA gt lt ELEMENT function functionname functionsignature functionpackage functiondescription gt lt ELEMENT functionname CDATA gt lt ELEMENT functionsignature CDATA gt lt ELEMENT functionpackage CDATA gt lt ELEMENT functiondescription CDATA gt
35. le aVar 101 XML Code lt newvariable name variable_0 gt 101 lt newvariable gt SWIP_startSequence Functionality This function is used to mark the start of a new sequence of activities All activities declared after the call of this function and the call of a corresponding SWIP_endSequence function will be executed as a sequence of activities Note The sequence may contain other activities that mark parallel or other execution types Implementation Remarks This function should add a lt sequence gt start tag to the document that describes the workflow SWIP_endSequence Functionality This function is used to mark the end of a sequence of activities Implementation Remarks A call to this function should result in adding a lt sequence gt tag to the document describing the workflow Example GAP code SWIP_startSequence STP endsegucnce J3 XML Code zeguen lt sequence gt SWIP_startMultiChoice Functionality This function is used to mark the container of multichoice brances The call to this function must have as direct descendants only calls to functions that mark the start end of a branch When all the branches were defined a call to the function that marks the end of the current container must follow SClEnce leAt Team 20 The CAS server User Manual Implementation Remarks This function should add a lt multichoice gt start tag to the document that describes the
36. ned by the executing CAS It is the responsibility of the client to parse the result and extract any useful information it may contain The result provided to the client has the structure lt ELEMENT OMOBJ OMSTR OME gt lt ELEMENT OMSTR CDATA gt lt ELEMENT OME CDATA gt where the OMSTR tag contains the result or in case of an error the OME contains the error message 4 1 2 Execution Management Interface In scientific computational field task execution management may be proven useful due to general characteristics of such tasks long running time amount of computational resources required by the tasks real time management of computational results Execution management may be achieved simple through the following operations e PAUSE enables the client to pause an already submitted task The client has submitted a task using an asynchronous call and therefore it waits for a call back message from the executing CAS Server with the response If a pause request is issued as a first consequence the call back containing the response is blocked regardless of the real execution status of the task at CAS Server level The CAS Server is not directly executing the task but it submits it further to a CAS If the execution CAS implements pause resume mechanisms the actual execution is paused If not the execution continues and when it finishes the result is stored so it may be provided to t
37. nitvalue gt 1 lt initvalue gt lt endvalue gt 10 lt endvalue gt lt foreach gt SWIP_readOutput Functionality The SWIP_readOutput workflowID function can be used to retrieve the result of the execution identified by the workflowID Implementation Remarks This function must invoke a remote predefined Web service of the system to supply the workflow identifier and to get the result of the computation Example The GAP code SWIP_readOutput SWIP_processHandler will retrieve the result of the process identified by the swIP_processHandler 6 Examples To show how our system can be used to implement scientific workflows from within a CAS we present next a couple of examples Note For simplicity several situations where variables are used in the examples below are shortened As explained above if the user declares a variable using the call SWIP_declareVariable n 0 the n variable represents a local GAP variable that will store a handler to the actual variable This means that for conditional constructs the use of the handler stored by n in the correct approach is SClEnce leAt Team 26 The CAS server User Manual SWIP_startChoiceBranch Concatenation n lt 10 that will result in the condition variable_1 lt 10 is not obtained by SWIP_startChoiceBranch Sn lt 10 Such several situations appear in the code above and are coded in this manner just to offer the user a clear picture of th
38. presenting a well formed XML document having the structure described by the following DTD lt ELEMENT noderespons reference filenamet error gt lt ELEMENT reference CDATA gt lt ELEMENT error CDATA gt An example of a success response for a object solver request is presented below lt noderesponse gt lt reference gt http host com skipped_ref document id lt reference gt lt filename gt gsiftp temp_dir filel lt filename gt lt noderesponse gt The message informs the client that during the resolve process a reference that was in the scope of a higher rank resolver was discovered and was not solved It also informs the client that targeted objects were saved and may be retrieved by transferring the file at the designated URL As the DTD shows the list of skipped references may contain more than one element Similarly the list of files containing the target nodes may contain more than one file but only one file is hosted on the current CAS Server The rest of files were created and are stored on partner CAS Servers that the current CAS Server had to contact in order to fully resolve the references encountered that were in its resolving scope If an error occurs during the resolve process an error message similar with the following one may be sent to the client lt noderesponse gt lt error gt An error message lt error gt lt noderesponse gt SClEnce le
39. result in an error Implementation Remarks Implementation of this function must result in ending the current workflow document by adding the lt workflow gt end tag to the document Example GAP code SWIP_startWorkflow SWIP_endWorkflow XML Code lt workflow gt lt workflow gt SWIP_declareVariable Functionality Declaration of a new variable may be achieved using the function call SWIP_declareVariable varName varValue The varName parameter is a local GAP variable that will hold a string representing the handler to the variable A variable declared with this function is intended to hold only simple data types that can be used in describing XPath condition Most common is that the variable will have a numerical value This kind of variables cannot be used as input parameters for invoke activities Implementation Remarks A variable declaration should be marked by adding a lt newvariable gt node with an attribute name having an automatically generate value that it is unique amongst all other variables declared so far The value of the name attribute represents the handler of the variable and it will be stored in the varName variable If the user supplies a varValue the lt newvariable gt node should have a child text node with the value varValue otherwise the 0 text node should be provided as a child Example GAP code SClEnce leAt Team 19 The CAS server User Manual SWIP_declareVariab
40. rver String getFunctionsMatch Sting match get the list of functions that are implemented by a CAS installed on any CAS Server and that have as a substring of their name or of their package name the string given as parameter For every matching function identification information regarding the CAS implementing it is also retrieved the CAS Server s service URL and the CAS name String getSymbolsMatch Sting match get the list of OM symbols that are supported by a CAS installed on the CAS Server and that have as a substring of their name or of their Cd name the string given as parameter For every matching symbol identification information regarding the CAS implementing it is also retrieved the CAS Server s service URL and the CAS name String getSupportedFunctions String CASServerURL Sting casName the list of functions that are implemented by the CAS with the casName installed on the CAS Server identified by CASServerURL String getSupportedSymbols String CASServerURL String casName returns the list of supported OM Symbols by the CAS having the name casName installed on the CAS Server identified by CASServerURL All operations specified above return results formatted as strings The results are well formed XML documents that contain the actual relevant information depending on the operation being invoked It must also be noted that the results contains information regarding only those CASs functions Op
41. ssigning that variable the value 1 and storing the handler of the workflow variable using the local variable varName A concatenation between 1 gt and the value of varName will have the expected result 1 gt variable_1 e variables that are meant to be used to link through data flows two or more invoke activities The input of one invoke may be thus be obtained from the output of one or more results of other invoke activities These variables contain values encoded in OpenMath and cannot be used in the contexts of conditional expressions for if while or other similar constructs A call to the SWIP_invoke result in declaring a variable that will store the result as an OpenMath object and the handler is returned by the function A attribution aVar invoke has the effect of storing a handler of the result obtained by the invoke in aVar variable This handler can be used in a following call to mark that the result is used as input data for another invoke aVar invoke CASID call where call is a string obtained by concatenation of several strings and variable handlers Let aVarl and aVar2 be two local variables that hold handles variable_I and variable_2 for to previous executed invokes To obtain the call of a remote function in the current implementation i e without full support for OpenMath encoding the call aFunction variable_1 Svariable_2 may be obtained by concatenation NaFunction
42. submitted in a previous synchronization call the custom message tailored for every registry may contain 2 If the registry was newly added to the CAS Server and no synchronization messages were exchanged between the CAS Server and the remote registry the message contains the list of CASs exposed by CAS Server for every CAS the capabilities of the machine were a particular CAS is installed for every CAS complete details about the functions and OpenMath symbols that are supported implemented by every CAS 3 If the main registry was already successfully informed by existing characteristics of the CAS Server but in the meanwhile several characteristics were updated by the CAS Server s administrator it contains full details of the entity that was changed and identification details regarding the related CAS For instance if the details regarding a certain function were changed the update message contains the details regarding the method and the list of the CAS that supports it Note Each entity described in an update message i e CAS method OpenMath symbol etc is identified by a unique key that does not change over time If a CAS named GAP is installed on a machine and it is registered through the Local Registry Administrator application its key is advertised to all related discovery registries If at a later time the administrator of the CAS Server decides to uninstall the GAP1 instance and add a new CAS called GAP2 it
43. such mechanisms The interface consists of two operations One operation allows third party clients to submit object requests while the other one is able to store responses for requests that the current CAS Server previously submitted to other CAS Servers The signature of the operations and their usage scenario is presented below fullSolveGetList used to submit to a CAS Server a request to resolve a list of references that are in the scope of the contacted CAS Server The references are in the scope of the CAS Server if the host used in the reference s URLs matches the host of the CAS Server This operation examines the list of references finds the targeted objects and stores them in a temporary file that is available for download Parameters requestID of type string represents an identifier of the request unique both in the scope of the client and the CAS Server request of type string represents a well formed XML describing the request The structure of the parameter is detailed in the following sub section callbackURL of type String represents the URL of the service implemented at client level waiting for the resolve response Returns nothing Fault OMRResolveFaultType requested errorMessage fullSolvePutList used to accept resolve responses from third party CAS Servers to which it has previously submitted resolve requests The request message contains a list of file URLs that may be used to retrieve
44. t falseBranch gt SWIP_endIf0 lt parallel gt SWIP_startParallel lt parallel gt SWIP_endParallel lt foreach gt SWIP_startForeach initValue endValue lt foreach gt SWIP_endForeach lt while gt SWIP_startWhile condition lt while gt SWIP_endWhile lt invoke gt SWIP_invoke CasID command varReference lt variable name var1 gt SWIP_declareVariable varName varValue value lt variable gt lt casID gt SWIP_invoke CasID command varReference lt call gt SWIP_invoke CasID command varReference lt initValue gt SWIP_ startForeach init Value end Value lt endValue gt SWIP_startForeach init Value end Value 5 1 SWIP package functions The list of the functions provided by the SWIP package for this version is presented below They may be used to describe arbitrary complex workflows if rules for well formed Remark1 Variables within the workflow are automatically managed by the current solution and with the direct support if the workflow execution engine The user may not access directly the values of the variables when the workflow is declared The only acces that the user has is to the handlers of a variable The system uses two types of variables e variables that are meant to be used in conditional expressions of while if etc This variables may only contain numerical values encoded as strings and not OpenMath encoded objects These numerical values may be use
45. tween the three CAS Servers depends on the nature of the resolving process required If the list of symbols is required CS1 will formulate the request to CS2 and will suspend the resolving process until CS2 contacts back the CS1 server with the response to the request The response contains the list of symbols discovered by CS2 or any other resolver further contacted by CS2 in our case CS3 A similar approach is used when the resolve process must obtain the actual OpenMath objects targeted by the references The difference is that the response contains a list of files that the interested client should download Using the above assumptions CS3 finds all the OpenMath Objects that can be found locally and stores them to a temporary file As a response it sends to CS2 the name of the file containing the target objects CS2 will receive the response from CS3 and will send to CS1 the file address received from CS3 and the name of the file where the OpenMath local objects were extracted As a final step CS1 will contact all third party servers and request the files containing the required objects The resolving process establishes a temporary hierarchy among the CAS Servers participating to a certain resolve process Establishing the hierarchy CS1 CS2 CS3 prevents CS2 to try to resolve references that target objects hosted on CS1 No CAS Server SClEnce leAt Team 9 The CAS server User Manual that has an inferior grade will try to solv
46. variable gt lt casID gt GAP lt casID gt lt call gt increment variable_1 lt call gt lt invoke gt lt while gt lt sequence gt lt foreach gt lt initValue gt 1l lt initValue gt lt endValue gt 5 lt endValue gt lt parallel gt lt invoke uniqueID invoke_3 gt lt casID gt Kant lt casID gt lt call gt GCD 1234 5678 lt call gt lt invoke gt lt invoke uniqueID invoke_4 gt lt casID gt Maple lt casID gt lt call gt ged 1234 5678 lt call gt lt invoke gt lt parallel gt lt foreach gt lt workflow gt References 1 S Freundt P Horn A Konovaloy S Linton D Roozemond Symbolic Computation Software Composability Protocol SCSCP specification Version 1 3 2009 http www symbolic computation org scscp SClEnce leAt Team 28 The CAS server User Manual 2 The OpenMath standard http www openmath org 3 GAP Computer Algebra System http www gap system org 4 Oasis Web Services Resource Specification http docs oasis open org wsrf wsrf ws_resource 1 2 spec os pdf SClEnce leAt Team 29
47. y interface The AGSSO Discovery interface is compound of several Web Service operations that the remote client may call in order to obtain useful information regarding the state of the system the list of CAS Server that are part of the computational infrastructure the list of CASs available and their supported functionality the status of execution for a certain workflow While tasks are usually planned automatically for execution by AGSSO there are situations when a user may require a certain task to be executed on a particular machine by a certain CAS For instance if the user requires that a certain task is to be executed by a GAP instance the user will state explicitly this information In this situation any CAS having its name starting with GAP may be used If in turn the user wants a GAP 4 0 instance he must specify so and all matching CASs can be used Every CAS installed on a CAS Server may be uniquely identified by its name and the name of the CAS Server it is installed on So it the CAS GAP 4 0 instancel installed on the CAS Server CS1 is targeted the user has to specify its full identification details In this situation the AGSSO will make sure that the task is sent to the specified CAS and no other The list of operations that allow the remote user to learn details regarding the capabilities of the composition infrastructure are String getAvailableCASServers returns the list CAS Servers that AGSSO is a
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