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JiVE: JAFMAS integrated Visual Environment

1. Conversation Editing Canvas Output Conversation j t Initial Initial Delete Conversation Add State Request Conversation Edit Control Final Final iii Tool Bar status Bar Popup Menu Figure 3 4 Conversation Design Window These GUIs are comprised of the following basic items Menu Bar The menu bar allows the user to access any of the commands applicable to this window at any time The items available on the menus are shown in Table 3 1 Tool Bar The Tool bar allows the user to select from a subset of the commands Status Bar The status bar shows the users what is going on in the system The status bar includes messages about what the user should do next when they select a specific command error messages from the server and information on what editing has taken place at this client and other clients 24 Menu Items in Agent Design Window Menu Items in Conversation Design Window File Menu Close Menu o Save Project o Close Window o Exit Edit Menu Edit Menu o Add Conversation o Add Type o Delete Conversation o Add Subscribe o Add State o Add Attribute o Delete State o Add Message o Mark State as Initial o Remove Type o Unmark State as Initial o Remove Subscribe o Mark State as Final o Remove Attribute o Unmark State as Final o Remove Message o Add Conversation Rule Edit Control Menu o Delete Conversation Rule o Request Agent Edit Control o Edit Conversation Rule o Relinqui
2. Required Resources Hew Ca ooo conca Waning Applet Window 00000000 4 4 We type in the name of the agent Customer The agent is of type Customer The attributes that this agent has are classified as Customer attributes The agent denotes the intent to subscribe publish to the only subject available which is Factory We also specify the type of resource this agent requires as Logistics This means that this agent will look for agents the have the attribute of Logistics After specifying each of the properties for the agent we select Okay The Add Agent Request is submitted to the server and we see a message in the status bar 4 indicating that the agent was added to the design and the agent appears on the Agent Design Panel We repeat this process for the two other agents Logistics and Plant Figure 4 2 shows the three agents as placed in the Supply Chain design Agents can be dragged around the design window and placed where desired Each agent once created has a set of conversations associated with it which must be added to the design Opening the Conversation Editor for that agent allows for the design and editing of the conversations 4 4 Designing the Conversations The Conversation Editor allows for the design and editing of the conversations for a particular fas JAFMAS integrated isual Environment JWE Conversation Design Window fo
3. m OK Cancel This window also indicates to the user those 2d _ Cancel subscription publication channels that were ENEE ENET A T Figure 4 9 Such That Property Design intended to be used Additionally on the Conversation Rule Editor the buttons labeled New allow for the addition of new messages to the system The creation of the conversations continues until the entire set of conversations states and conversation rules have been specified When we have designed the entire project we are ready to check our conversations for errors and then generate the source code for our project 4 6 Analyzing Conversations and Generating Code The analysis of the conversations is as easy as making a selection on the menu During analysis no changes can be made to the design In addition the analysis can take some time depending on the intricacies of the design and the processing power of the machine that is used as the server When the results are returned an alert will be provided concerning any problems in the design In our Supply Chain example we have not marked the Initial state of the conversation 47 AnswerFormLargeTeam as Final as well This The following errors were found in your conversations causes deadlock conditions to appear in the Your conversations are not live There are deadlock conditions in the agent conversations The deadlocks are encountered when the system is in the following states 2 z
4. Deadlock 1 analysis as shown 1n Figure 4 l 0 We then fix A token is in State Startin Agent Plantin Conversation AnswerFormLargeTeam A token is in State Start in Agent Plant in Conversation AnswerFormSmallTeam 7 er Atoken is in State Start in Agent Plant in Conversation KickOffexecution the error marking the Initial State of Conversation Rule Customer CustomerConversation cc6 has received an enabling messa Conversation Rule Logistics LogExecNet len5 has received an enabling message Conversation Rule Logistics LagExecNetlen8 has received an enabling message c 9 i Conversation Rule Logistics LogExecNetlen11 has received an enabling message AnswerFormLargeTeam as Final as well And The Conversation CustomerConversation has reached a final state The Conversation LogExecNet has reached a final state e e The Conversation FormLargeTeam has reached a final state when the analysis 1S run again 1t returns a The Conversation FormSmallTeam has reached a final state The Conversation KickOffexecution has reached a final state Deadlock 2 message stating that are conversations are ready tre eet tintin caninin inaintea Okay to go which means we can go ahead and jramgamewnes generate the source code Figure 4 10 Analysis Results The generation of the source code requires a click on the appropriate menu and if successful the files are stored on the server The automatically generated source code
5. The conversation rule sends a message before completion and this message is sent to the Customer agent with a message type of Reject Clicking Okay submits this conversation rule to the server and notification of the success of the operation is Logistics shown in the status bar In addition the len6 conversation rule has a suchThat method specified This means that the specified method s must return true before the conversation rule can continue If there are multiple methods specified they are evaluated using a Boolean And function Figure 4 9 shows the editor for the Figure 4 8 Specification of Message suchThat methods For each method that we would Sender Recipient like to add to the conversation we type it in the text box on the top of the dialog and click add In the case 46 of len6 we have added the method Edit methods for suchThat cannotRankContractors We are also able to remove any methods that we do not want by selecting them in the list on the bottom and clicking remove Add Remove In the Conversation Rule Editor Figure 4 7 Remove several buttons require additional description cannotRankContractors The button labeled Subject opens a Subscription Publication Information window which gives visibility of the relationships between each agent and each subject to assist in selecting the Sender and Addressee properties
6. 1 1 4 JAFMAS The Java based Framework for Multi Agent Systems JAFMAS Chauhan 1997 provides the basis for JIVE and resulting multi agent system design JAFMAS is a methodology and architecture for the design and implementation of multi agent systems in Java It focuses on communication agent interaction and multi agent system coherency and coordination JiVE enhances the use of JAFMAS by providing a visual environment for the design of the agents and their communications It removes the difficult and time consuming task of manually writing code to support communication between agents in a multi agent system Furthermore JiVE guides the designer through the JAFMAS methodology and automates the analysis of the conversation model before generating source code in JAFMAS format 1 2 Objective JiVE meets the following objectives e Collaborative support for multiple distributed users e A graphical interface for the design and visualization of multi agent systems e Automated design validation and error checking for multi agent system designs 2 e Generation of usable software code for the deployment of multi agent systems In addition to those main objectives other aspects are considered The JiVE architecture is a client server application allowing multiple users the ability to login to a design session The use of the Java programming language and the Java Foundation Classes in the development of JiVE provides platform indepen
7. Brink 1996 R S Brink A Petri Net Design Simulation and Verification Tool MS Thesis Department of Computer Engineering Rochester Institute of Technology September 1996 Available at http www csh rit edu rick thesis thesis html Chauhan 1997 D Chauhan JAFMAS A Java Based Agent Framework for Multi Agent Systems Development and Implementation Masters Thesis ECECS Department University of Cincinnati July 16 1997 Available at http www ececs uc edu abaker JAFMAS index html 58 Chen 1998 Q Chen JSIM A collaborative Environment For Web based Control System Design Masters Thesis ECECS Department University of Cincinnati March 1 1998 Cost et al 1999 R S Cost Y Chen T Finin Y Labrou and Y Peng Modeling Agent Conversations with Colored Petri Nets Workshop on Specifying and Implementing Conversation Policies of the Third Annual Conference on Autonomous Agents Seattle WA May 1 1999 59 66 David and Kraus 2000 E David and S Kraus Agents for Information Broadcasting Intelligent Agents VI LNAI Volume 1757 Eds N R Jennings and Y Lesperance Springer Verlag Berlin Germany 2000 91 105 d Inverno Kinny and Luck 1998 M d Inverno D Kinny and M Luck Interaction Protocols in Agentis Proceedings of the Third International Conference on Multi Agent Systems Paris France July 3 7 1998 112 119 Ehrlich 1999 K Ehrlich Chapter 1 Designing
8. e A message is received that enables this conversation rule meaning it has a specific message type and has been received from a specified agent or subscription publication channel e The doBefore method is executed e The status of all methods specified for the suchThat property is verified as true e The doAfter method is executed e lt A specified message is sent with a specific message type to a specified recipient either an agent or a subscription publication channel Not every item in the conversation rule s order of execution needs to be filled in for any given conversation rule A 4 4 1 Adding and Editing Conversation Rules To add a conversation rule in the Conversation Design Window select the Rule button from the toolbar or Add Conversation Rule from the Edit menu click on the starting state of the conversation rule then click on the ending state of the conversation rule This will bring up the Conversation Rule Editing Window as shown in Figure A 9 In this window the properties A12 desired for this conversation rule can be specified First fill in the name of the conversation rule noting that the name must be unique for that conversation From the pull down menu select the agent or subscription channel from which a received message comes and specify the received Message Type in order to enable this conversation rule If these properties are left out then the conversation rule will automati
9. is a final state and State and State3 are neither an initial nor a final state This conversation 21 has four conversation rules ConvRulel ConvRule2 etc ConvRulel for example points from Statel to State2 this denotes that if the conversation is in Statel and the conditions for ConvRulel are met then the messages and or computations associated with ConvRulel are executed and Conversation would transition to State2 If the user desired more information on any conversation rule they can expand that rule and view all of its properties Figure 3 3 shows JiVE s main graphical user interface GUI and Figure 3 4 shows the Conversation Design Window The use of each of these design windows 1s described as a part of the example given in Chapter 4 The features of these windows are described here 2 fea JAFMAS integrated Visual Environment JYE File Edit Edit Control Tools Help neta Editing Canvas Tool Bar ith ribute F ribute Delete Agent Agent Properties ent Request Edit Control of Agent Relinquish Edit Control Status Bar ssaqe Mm Popup Menu mac 25 LA T IYE initialized pe trpel added by System subject Subject added by System subject Subject added by System DSC Figure 3 3 Multi Agent System Design Window 23 fea JAFMAS integrated isual Environment JYE Conversation Design Window
10. generated by JiVE and even automatically deployed 5 3 4 Better Project Support For simplicity the current design limits the number of actively edited projects to one In order to allow multiple projects JIVE would need to maintain and control multiple instances of the JiVE Server In addition management of the communication between the clients and the multiple servers would need to be added to the server The ability for multiple projects to be active in the system would increase the usability of JIVE by allowing for an organization to 54 place the JiVE server in one central location and allow editing on any project at any time Additionally more comprehensive user management features would go along with this very nicely This could include interfaces for an administrator to manage the JiVE users and the ability to limit user access to certain projects as is done with the Administration client in TeamRooms Roseman and Greenberg 1996 5 3 9 Improved Analysis The performance of the Petri net analysis especially given certain constructs c f Section 5 2 could be improved This could be from the integration of better and more powerful Petri net analysis tools as well as supplementation by other formal methods For example the incorporation of a Z specification language analysis could allow for the incorporate programmatically controlled agent conversation while still allowing the analysis of the coherency of the system as a who
11. would be helpful Examples of this can be found in Inamdar 1997 and Chen 1998 The users could more effectively collaborate by drawing pictures and writing text directly to each other in tandem with their design efforts A feature that would go hand in hand with this would be improved visibility of the users logged in to the project Inamdar 1997 Chen 1998 As it stands now the users logged on to a JiVE a2 project do not have access to a comprehensive list of who else is currently working on the project As previously mentioned the addition of an Undo feature as found in Joint EMACS Ressel Nitssche Ruhland and Gunzenhauser 1996 would greatly enhance the usability of the collaborative environment allowing the users to back out mistakes and or errors while keeping the design consistent 5 3 2 Better Graphical Interface There is additional room for improvement and enhancement in some of the graphical aspects of JiVE The look and feel of the agents and conversations on the Design Panels could be improved in several ways First automatic positioning of the entities on the design panels e g agents states conversations would enable the designer to more clearly see what is already in the system without having to reposition the entities themselves The conversation rules positioning are currently straight lines between the start and end state The look and feel of the conversation design panel could be improved by better routing
12. 2 6 9 agents Type subject Subject added by System subject Subject added by System E Attributes and Subjects l Figure A 3 Multi Agent System Design Window The agent s Type is a property that specifies the general agent type For example in a supply chain an agent might be a Customer agent or a Plant agent The Multi Agent System Design Window allows for the addition and removal of these properties A6 To add an agent Type property push the Tune Add An Agent Type Property YP button on the toolbar or Add Type on the Edit menu A dialog box will open allowing HET ALE Customer for the specification of the name of the Agent Type clear cancel Wenning Applet Window S as in Figure A 4 When Okay is pressed the request to add a Type is sent to the JIVE Server A message will be shown in the status bar indicating Figure A 4 Add Property Window the success or failure of the operation ee E To remove an agent Type property push the button on the toolbar or Remove Type on the Edit menu A Remove Property window will appear where the Type to remove is selected and the Okay button is pressed This submits the request to the JIVE Server A message will appear in the status bar indicating the success or failure of the operation The agent s Attributes are a set of one or more properties that classify what kinds of acti
13. Galan Baker 1999 First each state in the automata is represented by a place in the Petri net This is a one to one mapping of states to places For each conversation rule present in the state machine a transition is added to the Petri net Again this is a one to one mapping of conversation rules to transitions For each conversation rule add an arc from the place corresponding to the beginning of the conversation rule to the transition Then add another arc from that transition to the place corresponding to the end of the conversation rule The transition must now be enabled by any and all messages which trigger that conversation rule l e the transition firing corresponds to the conversation rule receiving its required utterance and executing For each conversation rule do the following Add a place for each utterance that will enable that conversation rule Add an arc from the transition corresponding to each utterance that will enable it to the place s in the previous step If there are multiple utterances that will enable a conversation rule then the arc transition and arc corresponding to that conversation rule will need to duplication Add an arc from the place s in the previous step to this conversation rules transition or duplicated transitions For each final state in each conversation a transition is added For each final state an arc is added to its transition For each conversation one place is added and a
14. process is enhanced not hindered by the access control scheme utilized in JIVE allowing for the almost transparent sharing of a common design area and the assurance of consistent project data JiVE s design validation tool incorporates a unique approach to the verification of multi agent system communication The design of the multi agent system communications in the finite state machine format and the algorithm for conversion to a Petri net allow the designer to analyze 56 their design before deployment The accompanying direction for the resolution of design errors assists the designer in locating and fixing problems found in the analysis The design process is completed by allowing the generation of the source code in JAFMAS format allowing for the rapid deployment of the multi agent system The ability to add additional code to the system design and to subsequently regenerate the JiVE generated portion of the system allows designers to iteratively design their multi agent system This entire design process was exhibited with the design of a multi agent system supply chain which showed the ease of use and versatile features Overall JIVE is shown as a full featured multi agent system design tool which provides a quick and easy bridge between design and implementation 57 Bibliography Aknine and Aknine 1999 S Aknine and H Aknine Contribution of a Multi agent Cooperation Model in a Hospital Environment Proceedings o
15. 2 The entry point to the JiVE Client the Chent Communicator applet can be opened in a Java Enabled web browser or by using the JDK appletviewer as of this writing the major E EE ER Conversation Design web browsers were just beginning to on Panel support Java 2 The JiVE applet does nothing more than Conversation create the JiVE_Client object The Rule Editor JiVE_Client object opens a login Window object and creates a ClientCommunicator Figure 3 7 Client Architecture object Upon creation the login window must query the JiVE Server for the available current projects it does this using a TCP IP Socket on a predefined port The user can then attempt to login to the system either using an existing project or by creating a new project The login window attempts to validate the user by sending a message via the ClientCommunicator to the JIVE Server which validates the users name and password If the login is valid then the JiVE Client opens the Editor window otherwise the user can retry their login 31 The user is now looking at the main editing screen for the JiVE application and can begin constructing and or editing the multi agent system Chapter 4 provides a comprehensive description of the multi agent system design process The ClientCommunicator class handles all of the communication between the client and server for the client applet In general the communication that transpires when the user makes any
16. 3 3 Message NCS aioir a E A Eei 35 Taole ed ist OFT VEC ASSES eran a E E A A2 1 Introduction JiVE JAFMAS integrated Visual Environment allows a designer to draw a multi agent system graphically specify the necessary properties check the design for correctness and deploy their application This can all be done while working collaboratively with other designers located elsewhere 1 1 Background 1 1 1 Agents The definition of an agent is a topic that provides for much discussion In general an agent is a piece of software possibly with some intelligence with a well defined role and a set of goals it can even be autonomous or pro active Regardless of what properties the agent has it will work on the behalf of a user providing some service or data The concept of software working on our behalf is very appealing More importantly is that the agent can work more efficiently than a person and can take on tasks that would ordinarily not be appealing These tasks can include things that are highly repetitive computationally intensive or just plain mundane 1 1 2 Multi agent Systems A multi agent system is a conglomeration of agents which when acting together exhibit a greater system level behavior The designer programs this behavior in some cases and in other cases this can be an emergent behavior The system level behavior benefits from the individual actions of the agents Numerous multi agent systems have been deployed both
17. Add Type 40 from the Edit menu or the menu bar or we click on Type on the toolbar This presents us with a window where we type the name of the property Figure 4 3 shows the addition of a Customer type We proceed to add the remaining types peyer myp erren Logistics and Plant The Attributes are added in a similar manner Customer Logistics Paint and Transportation We also add the Subjects Assembly Hew Type Customer Ca Gear enea Waning Applet window 000000 that the agents can subscribe publish to which in this case is just one Subject called Factory Figure 4 3 Adding a Property After adding the various properties we can begin adding the agents The three agents that the Supply chain example has are Customer Logistics and Plant There are several methods by which we can add the agents including selecting from the menu bar from the toolbar or the popup menu To add the Customer agent we click on the s gent toolbar button and then click on the location in the Agent Design Panel where we want the agent to be placed The Agent property window appears allowing us to specify the properties of the Customer agent shown in Figure Agent Properties Window Editing Agenti X Agent Name Kustomer Agent Type Her Customer Attributes New Customer Logistics Assembly
18. Add Type Add Subscribe Add Attribute Add Message Remove Type Remove Subscribe Remove Attribute Remove Message Get Subscription Info Get Agent Properties Edit Agent Add Conversation Delete Conversation Move Conversation Get Conversation Prop Add State Delete State Move State Mark State As Initial Unmark State As Initial Mark State As Final Unmark State As Final Add Conversation Rule Delete Conversation Rule Get Conversation Rule Prop Edit Conversation Rule Check Conversations Get Agent Edit Control Get Conversation Edit Control Get Rule Edit Control Give Agent Edit Control Give Conversation Edit Control Give Rule Edit Control Refresh Data Generate Code Close Connection Table 3 3 Message Types Server Messages Sent to One Client Login Accepted Login Not Accepted Agent Not Added Agent Not Deleted Agent Not Moved Type Not Added Subscribe Not Added Attribute Not Added Message Not Added Type Not Removed Attribute Not Removed Message Not Removed Subscription Info Returned Subscription Info Not Returned Return Agent Properties Agent Properties Not Returned Agent Not Edited Conversation Not Added Conversation Not Deleted Conversation Not Moved Return Conversation Prop Conversation Prop Not Returned State Not Added State Not Deleted State Not Moved State Not Marked As Initial State Not Unmarked As Initial State Not Marked As Final State Not Unmarked As Final Conversation Rule
19. IP Socket connection with a potential client Upon validating the client s login data the server puts the socket into an index of active client sockets See Figure 3 6 The mechanism that controls the communication between each client and the server is an object called SocketManager Each client connects to the server through one of these SocketManager objects which is running as an independent thread and listens to the socket connection with the client for a message Upon receiving a message the socket manager passes the message to the ServerCommunicator object for handling The ServerCommunicator object s tasks include e Keeping track of the various clients that are connected to the system via the socket managers e Registering new clients as they log in e De registering clients as they log out or if their connection gets broken e Processing messages coming into the server and messages going out of the server 30 3 3 3 JIVE Client The JiVE Client is written using the Java 2 Swing components Swing is the name Sun has given to a set of lightweight GUI components This includes a lightweight version of many of the Java 1 x GUI components The JIVE Client is implemented as a series of windows which are all descendant from a JApplet The Swing equivalent of an Applet object Figure 3 7 illustrates this architecture Not shown in the figure are the various dialog boxes used in the client outlined in Table 3
20. Not Added Conversation Rule Not Deleted Return Conversation Rule Prop Conv Rule Prop Not Returned Conversation Rule Not Edited Request Agent Edit Control Request Conv Edit Control Request Rule Edit Control Code Not Generated Server Messages Sent to All Clients Agent Added Agent Deleted Agent Moved Type Added Subscribe Added Attribute Added Message Added Type Removed Subscribe Removed Attribute Removed Message Removed Agent Edited Conversation Added Conversation Deleted Conversation Moved State Added State Deleted State Moved State Marked As Initial State Unmarked As Initial State Marked As Final State Unmarked As Final Conversation Rule Added Conversation Rule Deleted Conversation Rule Edited Return Conversation Analysis Relinquish Agent Edit Control Relinquish Conv Edit Control Relinquish Rule Edit Control Code Generated There are of course various utility message types such as login messages save messages edit control messages code generation messages and analysis messages Table 3 3 also lists these 35 3 3 5 Agent Entity Representations A group of objects that represent the entities in a multi agent system facilitates the handling of editing and communication within JiVE These objects are internal to the JiVE system but have a one to one correspondence to the entities in the multi agent system design The following are represented in the system Agents Conversations Conversati
21. Project and Existing Project which can be toggled using the button in the lower right hand Fes Login Window corner of the window The figure shows the window in New Project mode User Name Alan Password ere Project Name SupplyChain Language Standard project and select the agent communication language ACL that the project will use The Okay Clear Exist Project waming Applet Window OOOO O A 4 1 1 New Project To create a new project type the name of the name of the project can be any valid directory name for the server file system The language property of the project needs some more iene Eee VERE Oe description The language property refers to the Agent Communication Language ACL that the multi agent system will use Three possible ACLs can be specified for a multi agent system in JiVE The default or Standard language selection utilizes a subset of the JAFMAS Message class This means that the designer must specify the Type of each message and optionally may specify the Intent of a message In addition to the Standard language option there are pre defined agent communication languages that are built into JIVE KQML and FIPA ACL These choices preload a set of performatives into the set of available messages These performatives conform to the standard set of performatives of KQML Labrou and Finin 1998 and FIPA ACL FIPA 1997 For more informati
22. Upon receiving a message from a 33 client the message passes to the ServerCommunicator for handling On the other end of the communication channel the client uses a similar object ClientCommunicator to handle all messages coming in from the server and going out to the server All of the communications between the clients and server utilize the JiVE_Message class The JiVE_Message class allows for the storage of key value pairs that can be sent via the socket i e it implements the Java Serializable Interface and extracted on the other end The fields that are included in each JiVE_Message are extracted in the Communicator objects on either end of the communication channel Table 3 3 outlines the different messages sent between the clients and the server The clients only communicate with the server The server however can communicate with all of the clients One set of server message types are sent only to the client who originally made the request These generally are failure messages like Agent Not Added that would indicate to the client who tried to add the agent why the request failed or requests for information Another set of server message types are sent to all clients currently logged on to the project These messages are generally successful editing messages which indicate to all users that there has been a change to the design 34 Client Messages to Server Login Save Add Agent Delete Agent Move Agent
23. a message This represents a subset of the available fields in a JAFMAS Message the user can optionally manually specify additional message fields by editing the generated source code The Standard choice provides the greatest flexibility Besides the Standard choice there is the option to utilize one of the predefined agent communication languages built into JIVE which includes KQML or ACL The KQML and ACL language choices preload a set of performatives into the set of available messages These performatives conform to the standard set of performatives of KQML Labrou and Finin 1998 and FIPA ACL FIPA 1997 To support these Agent Communication Languages there are two message classes included with JiVE that extend the original JAFMAS messaging class These classes KOMLMessage and ACLMessage allow the user to manually fill in the remaining fields i e besides the performative and then can be used in much the same way as the original JAFMAS Message class 3 3 4 JiVE Communication The communication between the clients and the server are TCP IP Socket connections On the server side the Socket is originally opened in the JiVE_Server class which passes it to the ServerCommunicator who registers the client and creates a SocketManager object to listen for any client communication The SocketManager is a threaded object that allows the server to listen to more than one socket allowing for multiple clients
24. a web server The web server can serve the JiVE Client applet to users who wish to log in to a JiVE session on a JiVE Server When a user starts the applet they will be given the opportunity to log into the JiVE_Server The JiVE_Server validates the user s logon which in turn starts the main agent design window and gets the initial state of the agent design The user 1s now logged JIVE Client JWE Client on to the JiVE System As multiple clients log on to JiVE the multi agent system can be designed collaboratively d distributedly The JiVE_S epee nee ore pe ane ee Figure 3 5 General JiVE Architecture has full access to all of the Server s file 29 Clients Clients Figure 3 6 Server Architecture systems so that when prompted by a client the source code can be generated or the project file can be saved for later use Figure 3 5 illustrates this architecture 3 3 2 JIVE Server The JiVE Server is written as a Java application The JiVE Server running on the web server listens for any clients trying to connect to it The JiVE Server actually listens on two different ports for two different types of client messages First there is a LoginServer object which responds to queries by the various login clients telling the clients what projects are currently available on the server The client also has the option of creating a new project Second the server listens to a port in order to make the TCP
25. as being autonomous goal directed reactive or declaratively programmed Others limit agents to the role of representing a user or database Huhns and Singh 1998 Given these disparities it remains that an agent should provide a service to the user working toward some goal while representing the user s interests Linking these possibly intelligent and or autonomous agents together forms a conglomeration of agents termed a multi agent system This type of system is characterized by multiple independent entities working towards a common goal or solving a problem or set of problems They interact within themselves and possibly with the environment and or outside entities 2 1 1 Specification of Conversations and Conversation rules The cornerstone of a multi agent system 1s the communications Conversations allow the agents to interact and dictate the behavior of the system The specification of the conversation rules is an important aspect of the design and realization of multi agent systems A graphical representation usually provides the easiest description of agent conversations The tendency is to resort to a formal methods approach to specifying the conversations The most common means of representation are Petri nets or state machines 4 COOL Barbuceanu and Fox 1995 presents an example of the specification of communications where they use a finite state machine to represent each agent s communication parameters Chauhan fu
26. can now be generated The generation of the source code requires selecting Compile Code from the Tools menu and if successful the files are stored on the server in the appropriate directory c f Section A 1 2 A 4 5 1 Tips for Designing a Multi Agent System using the Analysis tool There are several aspects of designing a multi agent system using JiVE that will allow the analysis tool to work more effectively e Build the design incrementally This will allow analysis checking as additional functionality is added to the design and it will allow the analysis tool to assist in creating a coherent multi agent system design e For conversations that may or may never be started according to the design specify the Initial state as a Final state also In the absence of this the analysis will flag a deadlock condition e Avoid using a single subscription publication message many different places in the design This will tend to make the Petri net underlying the analysis grow very large The result is an analysis that will take a long time to complete A 4 6 Collaboration The collaborative features of the design environment are in many cases transparent to the user That is the user does not need to worry about edit control for the entities on which they are working Al5 The access control is applicable at several different levels namely e Agent Edit Control e Conversation Edit Control e Conversation Rule Edit Co
27. changes to any of the entities in the design goes as follows The GUI uses the ClientCommunicator to send a message to the server The JiVE_Server handles the editing AboutDialog This is a small dialog box that gives information about the program and its author when opened from the About menu selection AddPropertyWindow This dialog box is used for adding any of the basic agent properties to the system such as agent types attributes and subjects It is opened from the JiVE_Client window AgentPropertiesWindow This dialog box is used for editing the properties of a given agent either upon creation or for later editing This is opened from the JiVE_Client window ConversationPropertyEditor This dialog is used for adding a conversation and for editing the name of the conversation ConversationRuleChooser This dialog allows the user to indicate which conversation rule they are attempting to select when it is ambiguous EditMethodsWindow This dialog box allows the user to specify the methods to be called by the suchThat clause of a conversation rule It is opened from the ConversationRuleEditor window HelpWindow This is a small dialog box that contains help text when the user selects a help button or menu item This window is opened from various locations in the system InformationWindow This dialog box displays a block of text to the user for informational purposes and is opened from various locations in the GUI Message
28. from the Supply Chain example is given in Appendix C 4 7 Collaboration The collaborative features of the design environment are in many cases transparent to the user That is the user does not need to worry about edit control for the entities on which they are working This is a small description of a case where the user would deal with edit control Collaboration only comes into play when more than one user is working on the same project at the same time As mentioned in Section 3 2 1 access control applies to several different entities in the multi agent system design i e Agent Conversation Conversation Rule For this example in utilizing the collaboration feature we will reference a particular Agent named Customer In this example the first user to login to the system has the user name Alan Alan is the user who created the project as well as the agent Customer When Alan created Customer that user was automatically given edit control of the agent Alan had the ability to move that agent edit that agent s properties or delete that agent if desired The next user named User logs into the project that has already been started by Alan When User logs in the current system will be initialized and displayed on their client window User may want to move the agent Customer that was previously added to the design by Alan so User tries to move the agent
29. in Table A 1 Al AboutDialog JiVE AgentRepresentation AddProperty Window JiVE_Client CodeGenerator AgentDesignPanel JiVE_Constants ConversationRepresentation AgentPropertiesEditor JiVE_Message ConversationRuleRepresentation AgentRepresentation LoginWindow JiVE_Constants ClientCommunicator MessageEditor Window JiVE_Message ConversationDesignPanel MessageRepresentation JiVE_Server ConversationEditor RemovePropertyWindow LoginServer ConversationPropertyEditor StatePropertyEditor MessageRepresentation ConversationRepresentation User PetriNetRepresentation ConversationRuleChooser Images gif PetriNetTranslator ConversationRuleEditor PetriToolRepresentation ConversationRuleRepresentation Repository EditMethods Window ServerCommunicator HelpWindow SocketManager Information Window User Users txt index html All files in PetriTool directory The JiVE Jar file Table A 1 List of JIVE Classes A 1 2 File Structure Figure A 1 shows the JiVE directory structure The Installation Ditectory JiVE distribution zip file will create this directory Hi wE structure in the installation directory when qa KRES extracted The installation directory contains a images directory with the complete set of javadoc generated Ee documentation docs The directory containing all IE a of the JIVE Source Code and class files is called E JiVE and has a child directory that contains the Ee e images used in the JIVE Client The directory L Backups co
30. in academia and industry ranging from patient scheduling in a hospital Aknine and Aknine 1999 to climate control of a building Ygge and Akkermans 1997 in areas as varied as Information Broadcasting via the Internet David and Kraus 2000 and supply chain integration Nissen and Mehra 1999 The benefits of a multi agent system are many and in most cases can include flexibility scalability decentralization and robustness 1 1 3 Multi agent System Design Tools The complex nature of agents and even more so multi agent systems suggests that additional tools are required to assist in the design and implementation process This is true for all but the simplest of agents and systems The tools that we call on to assist us range from the low level frameworks to the higher level integrated development environments Each level of abstraction allows for a unique view into the construction and deployment of multi agent systems They each also provide a unique set of benefits to the system The lower level frameworks provide a designer assistance for a certain subset of design issues for example handling communication or agent mobility The higher level tools provide an abstracted view of the multi agent system allowing the designer to concentrate on the macro level behavior leaving the lower level details to the design tool As is the case with JIVE the higher level design tool can leverage a lower level tool to provide a comprehensive solution
31. in the design 43 The conversation rules displayed as an arrow between two states specify the conditions needed to transition between two states in a conversation as well as the result of that transition To add the conversation rules after selecting Add Conversation Rule from the menu bar or Rule from the toolbar we click on the starting state for the conversation rule followed by a click on the ending state of the conversation rule The conversation rule appears as a directed line between the start state and the ending state labeled with the conversation rules name The conversation rule editor window is shown where we can specify the conversation rule s properties 4 5 Designing the Conversation Rules Each conversation rule has a set of properties that defines the means by which the conversation fas JAFMAS integrated Visual Environment JYE Conversation Design Window for agent Logistics f oO x Close Edit Edit Control aConv eae Jes LogExecMet TR mS Input Fo ss Customer b Tell Messages a Propose Customer Logistics b p mine nv Logistics b Reject Proposed nn Accepti k Customer b Logistics b Proposed State gt Rejectt aT gt Logistics soe F ET State Logistics b Fropose gt Reject Logistics Logistics b Accept gt 5ati Customer b Logistics Achiewe gt F ail Logistics Satisfy Customer Fail Customer PE i Messages neee erm nn Propose Accept gt Rej
32. in the system We see two arrows going out to Agent3 and Agent4 and two coming in to the agent from Agent2 and Agent4 With this information for each agent appearing on the Agent Editing screen we can see the interactions between the agents but not overwhelming details about the substance of those communications A 4 3 Designing the Conversations For each agent added the agent s conversations must be specified The conversations for a particular agent including the states and conversation rules are added and edited from the Conversation Design Window as shown in Figure A 7 To bring up the Conversation Design Window and edit an agent s conversations click the alts button on the toolbar or on Edit Conversation from the Edit Menu A9 EAJAFMAS integrated Yisual Environment Ji VE Conversation Design Window The Conversation Design Window allows for the adding Conv and editing of several entities Conversation Menu Bar Conversation Editing Canvas First there are the conversations themselves labeled rectangles with a side Delete Conversation Add State bar on each side There can be Request Conversation Edit Control multiple conversations on a mRule status Bar Popup Menu Conversation Design Window These conversations represent the entire set of communications for the corresponding agent 1 e the Figure A 7 Conversatio
33. interfaces for the design and development of a multi agent system It provides various graphical tools including project management ontology management agent management protocol management and run time engines AgentBuilder is Java based and its communication language is KQML The AgentBuilder agent model consists of agents that have beliefs capabilities commitments intentions and behavioral rules Given an agent model s initial state and external influences the agent operates and communicates with the external world which in turn modifies it s states Reticular 1999a An interesting agent based system designed using AgentBuilder is a prototype system for buying and selling power generation capacity Reticular 1999b 2 3 2 ADE Another commercial multi agent design tool is ADE Agent Development Environment by Gensym ADE is an Integrated Development Environment for Distributed Multi Agent Applications which is built on G2 an Object Oriented graphical environment ADE provides a graphical language called AdeGrafcet an extension of the French Grafcet standard which is based on Petri net representations for the specification of the agent s behavior ADE provides a communication middleware utilizing subject based addressing ADE also has a simulation environment for simulating the design before implementation as well as a debugging environment Mehra and Nissen 1998 2 3 3 ZEUS ZEUS 1s a toolkit for building distributed mul
34. java Follow the directions in the JAFMAS System Administration and Users Manual Chauhan 1997 The only exception is when starting the agents themselves as described next A 5 3 Starting the Agents Agents generated by JiVE use a slightly different mechanism for launching then those using the original JAFMAS This is because using JiVE generated agents relieves the user from having to use the CreateAgent interfaces as specified in JAFMAS In fact JiVE allows the specification of the agents to create at design time The recommended method for deploying the application is outlined here specific applications may have different needs A17 Each agent created with JIVE has a main method included such that it can be directly run the agent from the command line An agent called Agent1 in the file called Agent1 java would be compiled as above and executed with the following command in Windows start java Agentl Or in Unix java Agentl amp Each agent in the JiVE generated system must be started using these commands in order to deploy the multi agent system It may be useful to create a batch file to start all agents in one command this would of course incorporate system specific constructs such as paths and classpaths A 6 References Brink 1996 R S Brink A Petri Net Design Simulation and Verification Tool MS Thesis Department of Computer Engineering Rochester Institute of Technology September 1996 Availab
35. message handling protocol KQML consists of three layers the content layer the message layer and the communication layer The content layer consists of the content of the message The communication layer handles the lower level communication parameters The message layer consists of a performative which conveys information about the content of the message as well as optional information to describe the content language Labrou and Finin 1998 FIPA ACL is another ACL with a format similar to that of KQML ACL messages use a set of parameters the first representing the communicative act of the message The additional parameters specify items to aid in message delivery to assist in the interpretation of the content and to allow the receiver to respond co operatively FIPA 1997 2 2 JAFMAS As the title of the software indicates JiVE builds heavily on JAFMAS Java Based Framework for Multi Agent Systems Chauhan 1997 JAFMAS provides a methodology and a framework for designing multi agent system JiVE uses the five step methodology provided by JAFMAS Identify the Agents Identify the Conversations Identify the Conversation Rules Analyze the Conversation Model Implementation of Multi agent system The JAFMAS software architecture provides a set of classes for the implementation of the multi agent system as proscribed by the methodology These classes provide support for the sending and processing of broadcast and direct
36. of architecture and messaging to that of JPECS JiVE does improve upon access control issues of a collaborative programming environment JiVE provides a more fine grained view of access control entities in the system and makes the access control more transparent c f Section 3 2 1 JIVE does not though 13 provide a full set of user communication tools such as a whiteboard or a chat board and does no user privilege control 2 4 4 2 JSIM JSIM Java Simulator was built on JPECS Inamdar 1997 and provides a collaborative tool for the definition and simulation of control systems JSIM provides a multi user communication utility and a block diagram editor There is also a conference management utility to allow multiple design sessions to run concurrently Chen 1998 JSIM like JPECS provides a basis for the JiVE architecture and user control facilities 2 4 4 3 Joint EMACS Joint EMACS is an EMACS style text editor that allows for the collaborative editing of documents It supports a high degree of fine grained mutual awareness and has well developed methodologies for handling concurrency control Ressel Nitssche Ruhland and Gunzenhauser 1996 In addition to the comprehensive handling of concurrency control which JiVE also uses Joint EMACS provides mechanisms for Undo operations which could be a useful feature in a tool such as JiVE 2 4 4 4 TeamRooms TeamRooms is a collaboration tool that allows for collaboration eith
37. practices of a user can adapt over time in response to a technology In many aspects this is the opposite of what an application developer should desire An application should leverage the natural way that a user thinks about the work involved and design towards that end enhancing the user experience not hindering it 2 4 1 2 Methodologies 11 Some methodologies for establishing the work practices involved in a groupware application are ethnography participatory design and action research Ehrlich 1999 Ethnography refers to the act of observing the end users of an application in action to evaluate their work practices This can involve watching their actions interviewing and participation The application of these findings can have very positive impacts on the application design Participatory design allows the end users to be actively involved in the design process Action research also involves observing the end users of an application but in an attempt to improve the processes through the implementation of the technology 2 4 2 Architecture Greenberg and Roseman discuss the merits of centralized vs replicated architectures Greenberg and Roseman 1999 A centralized architecture is one that has a main application located on a central server machine Clients submit request to the server and display the results based on the server s Output In this case the server can handle all concurrency and synchronization locally All client
38. 48 User receives a message in the status a0T eit Renter x bar c f Figure 3 3 back from the server User User requests Edit Control of agent Customer indicating that the move operation was not successful because User does not have edit control At this point if User wants to move the agent they must request the edit control of Customer They do this by selecting Regest Edit Figure 4 11 Edit Control Request Dialog Box Control of Agent from the Edit Control menu on the menu bar and clicking on Customer or selecting it from the popup menu This request is sent via the Server and Alan sees a pop up box as shown in Figure 4 11 saying the Edit Control of the agent Customer is requested by User Alan can then select Relinquish Edit Control from the popup menu or select it from the Edit Control menu on the menu bar and click on the Customer agent All users in the system will see a message in their status bar stating that edit control of Customer has been relinquished User is now free to move the Customer agent and upon moving it will automatically receive edit control 4 8 Using the Design To generate the source code for the multi agent system design select Compile Code from the Tools menu on the menu bar The source code is generated and placed in the project directory see Appendix A 1 2 The source code ge
39. 6 4 7 4 8 Supply Chain Project Initialization Designing the Agents Designing the Conversations Designing the Conversation Rules Analyzing Conversations and Generating Code Collaboration Using the Design ll 13 13 15 17 17 17 17 18 18 19 19 20 26 28 29 29 30 31 33 36 38 39 39 39 40 42 44 47 48 49 4 9 Summary 5 Discussion and Future Work Better Project Support 5 1 Summary 5 2 Discussion 5 3 Future Work and Enhancements 5 3 1 Improved Collaboration features 5 3 2 Better Graphical Interface 5 3 3 Improved Efficiency During Design 5 3 4 5 3 5 Improved Analysis 5 3 6 Improved ACL Support 5 3 7 Improvements in Agent Design 5 4 Summary Bibliography Appendix A Users Manual Appendix B JiVE Source Code Appendix C Supply Chain Example Source Code il 50 5I 5I 5I 52 52 a 53 54 E E E 55 56 o Al Bl CI List of Figures Faure o aJiV 5 Agent Representa oine E 20 Figure 3 2 JIVE Agent Conversation Representation ccccccccccccccscsssseseeeeeeeeeeeceeeeeeeeeeaaaags 21 Figure 3 3 Multi Agent System Design Window cccccccccccececeeeeaeeseseeeseeseeeeeeeeeeeeeeaaaaeaes 23 Figure 3 4 Conversation Design Wind0w ccccccccccsssssssseeseseeeececeeeeeeeeeeeeeasseaeeesesseseeeeeeeeeeees 24 Figure 3 5 Genetaljiy E ATDOT 15 E aoa naa 29 Paste S O Server A Tc MIleC U E aa
40. E EEE made iotetucennmeeys 30 Piste 327 2 C Heit Arent CULE ase wea annndstentniddw sige states a a 31 Piute 3 5 Object RelatiOms tp saxasciacistocn ican E E tena neha aes dei asanse tua vesacamlana 37 Foue a toa VV 10 OWN aeaa ate eaten hea case EE E T A aw 39 Piste Aa D CS1 Omi NGA OCIS EE a R 40 Figured ys ACdInG a Proper Y noice E E 41 Piouite 4 4 ACen Propi asa a E E T E E S 41 Figure 4 5 Customer Agent s Conversation Design ccccccccccccesessseecececeeeseaaeeseeceseeseaaeeeeees 42 Figure 4 6 Logistic Agent s Conversation Design ccccccccccccececcueceeesssessesseseeescceeeesseananegs 44 Figure 4 7 LogExecNet Conversation Rule Design emacs enei e T 46 Figure 4 8 Specification of Message Sender Recipient cccccccceececcccceeeceeaeeeeeceseeeeaaeeeeees 46 Figure 4 9 Such That Property Design cc cc cccccccccccecesseseeeeceeeeeeeseeeeeeeeceeeessaaeesseeeeeeeeeauaaenees 47 Figure Alos Analysis ReSUNSts2 ci clus lecsthe cm E a ee eae 48 Figure 4 11 Edit Control Request Dialog BOX c cc ccccccecesesceceeeceeeeeeceaeaeeeeeeeseseeeeeeeeeeeeeeaeaaags 49 List of Tables Table 2 1 Comparison of JIVE with Exisiting Multi System Design Tools cccccceeeeeee 10 Table al Liston di VE Menu emanen batecs het Selec dc et ates scuraeehea en iscts eddies 25 Table 3 2 List of Dialog Boxes and Their Functions ccccccccccccccsseseeeececeeeeaaeeeeeceeeeeeaaeeenes 32 Table
41. Groupware Applications A Work Centered Design Approach Computer Supported Co operative Work Ed M Beaudouin Lafon John Wiley amp Sons West Sussex England 1999 1 28 FIPA 1997 FIPA Part 2 Agent Communication Language FIPA 97 Specification Foundation for Intelligent Physical Agents Geneva Switzerland November 28 1997 Available at http drogo cselt stet it fipa f7a12 zip Galan and Baker 1999 A Galan and A D Baker Multi Agent Communication in JAFMAS Workshop on Specifying and Implementing Conversation Policies of the Third Annual Conference on Autonomous Agents Seattle WA May 1 1999 67 70 Graham and Decker 1999 J R Graham and K S Decker Towards a Distributed Environment Centered Agent Framework Intelligent Agents VI LNAI Volume 1757 Eds N R Jennings and Y Lesperance Springer Verlag Berlin Germany 2000 290 304 Greenberg and Roseman 1999 S Greenberg and M Roseman Chapter 6 Groupware Toolkits for Synchronous Work Computer Supported Co operative Work Ed M Beaudouin Lafon John Wiley amp Sons West Sussex England 1999 135 168 59 Hughes et al 1996 J Hughes J O Brien M Rouncefield and T Rodden They re Supposed to Be Fixing it Requirements and System Redesign CSCW Requirements and Evaluation Ed P Thomas Springer Verlag London 1996 21 38 Huhns and Singh 1998 M N Huhns and M P Singh Chapter 1 Agents and Multiagent syst
42. In practical terms for the current implementation this could mean the replacement of the Code Generator portion of the software with an analogous generator for a different framework The design and implementation of a multi agent system with the validation of the coherency of the conversations all using a graphical interface has significant value for a designer Even more value could be added to the design cycle by real time debugging of the agent system For example after designing and checking the system and generating and implementing the source code the user could then run the system and watch the activity in the agent conversations in the same or similar interfaces in which they were designed 5 4 Summary JiVE is presented in this thesis as a tool for the design and implementation of multi agent systems JiVE has several aspects that make it an exceedingly useful multi agent system design tool JiVE consists of a set of intuitive graphical interfaces allowing a designer to handily implement a multi agent system The interfaces including the agent design window and the conversation design window provide a glimpse of the multi agent system at varying levels of detail The built in collaboration features of JIVE provide the added flexibility of designing the multi agent system in a group This group of designers need not be located in the same room or even in the same building so long as they have a connection to the Internet The group design
43. JIVE JAFMAS integrated Visual Environment A thesis submitted to the Division of Research and Advanced Studies Of the University of Cincinnati In the partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in the Department of Electrical and Computer Engineering and Computer Science of the College of Engineering 2000 by Alan K Galan B S E E University of Cincinnati Committee Chair Dr Albert D Baker Abstract JiVE JAFMAS integrated Visual Environment is a software tool for the design and implementation of multi agent systems JiVE allows a designer to draw a multi agent system graphically specify the necessary properties check the design for correctness and deploy their application This can all be done while working collaboratively with designers located elsewhere JiVE draws on research in agents multi agent systems and system design JiVE offers a set of intuitive easy to use interfaces that enable a designer to completely specify the agents and agent interactions in a multi agent system Also presented in this thesis is an algorithm to check the coherency of the multi agent system This algorithm integrated into JiVE gives one touch access to design verification The compilation of the multi agent system and the generation of source code in JAFMAS format follows design verification Furthermore the ability for distributed collaborative work enhances JiVE s features JiVE pulls from the wo
44. To remove an agent s conversation from the Conversation Design Window select from the toolbar or Remove Conversation from the Edit menu and click on the conversation to be deleted Note Removing a conversation will also remove all states and conversation rules in that conversation The conversations can be moved around the Conversation Design Window s Editing Canvas by just clicking and dragging on any empty area of the conversation rectangle A 4 3 2 Adding and Editing States After adding a conversation states can be added to the design To add a state select State from the toolbar or select Add State from the Edit menu and click inside one of the conversations This will open a dialog box where the name of the state can be specified the name of the state must be unique for that particular conversation Boxes indicating whether or not the state should be an Initial state or a Final state can also be checked Clicking on Okay submits the request to the JiVE Server which responds with a message indicating success or failure in the Status Bar Upon success a circle will appear in the conversation with the name of the state To remove a state select Se from the toolbar or select Remove State from the Edit menu and then click on the state to remove The status bar will show the success or failure of the operation and the state will disappear from the Editing Canvas Note Any c
45. at represent the services that this agent can provide to the system e Agent Type The type of the agent e Required Resources 0 or more attributes that this agent needs from other agents in the system 36 m Ai Irw 1 f Bacana 1 Subject Figure 3 8 Object Relationship Subject Zero or more multicast channels to which this agent subscribes publishes User The user object representing the user in the system who has edit control of this agent Conversations The conversations of this agent Represented by ConversationRepresentation objects The properties of a conversation are represented in the ConversationRepresentation object and are Conversation Name The name of the conversation States The states in this conversation The information about which states are initial states and which are final are also encapsulated in this object Users The user object representing the user in the system who has edit control of this conversation Conversation Rules A list of the conversation rules that are contained within this conversation The ConversationRuleRepresentation represents each these 37 The properties of a conversation rule are represented in the ConversationRuleRepresentation object and are as follows e Conversation Rule Name The name of this conversation rule e suchThat A list of the methods to invoke in the suchThat method of the conversation rule Each of these methods should be
46. ation rule These methods can be found 1n the classes for each conversation rule In addition supplemental code can be added to the agents and conversations to provide additional behavior to the multi agent system Finally once any necessary modifications and additions have been made to the design the system can be deployed The details on compiling and running the agents are included in the JiVE Users Manual in Appendix A 4 9 Summary This chapter has presented an example design session using JiVE Each aspect of designing a multi system was explored and described Appendix A the JIVE User Manual provides more details on the specific commands and their use 50 5 Discussion and Future Work This thesis presented a graphical multi agent design tool This chapter will discuss the presented work and suggest future improvements and enhancements 5 1 Summary This thesis presented the design and implementation of a design tool for the development of multi agent systems JiVE provides an easy to use interface for drawing the multi agent system including visibility of the agent conversations and conversation rules The coherency and coordination of the set of agent conversations can be verified using JiVE s PetriNet translator and an external Petri net analyzer JiVE collaboration support further enhances the design process by allowing users in different locations to work on the same project Furthermore JIVE is platform independ
47. ave contributed much to my life in many ways To my friends and family I extend my thanks to each of you your various contributions to my life have meant a lot Table of Contents Table of Contents List of Figures List of Tables 1 Introduction 1 1 Background 1 1 1 Agents 1 1 2 Multi agent Systems 1 1 3 Multi agent System Design Tools 1 1 4 JAFMAS 12 Objective 1 3 Overview 2 Literature Review 2 1 Agents and Multi agent Systems 2 1 1 Specification of Conversations and Conversation rules 2 1 2 Agent Communication Languages 2 2 JAFMAS 2 3 Multi agent System Design Tools 2 3 1 AgentBuilder 2 3 2 ADE 2 3 3 ZEUS 2 3 4 DECAF 2 3 5 MASSYVE Kit 2 3 6 JADE 2 3 7 KAoS 2 3 8 Bond 2 3 9 Comparison of Existing Design Tools with JIVE 2 4 Collaboration 2 4 1 Requirements 2 4 2 Architecture iv 0 OO o OHO OHO CO NN N 11 11 12 2 4 3 2 4 4 2 5 Concurrency Example Groupware Systems Summary System Design 3 1 Seed 3 1 2 3 1 3 3 1 4 3 2 32l 3 22 3 2 3 3 2 4 3 3 3 3 1 3 3 2 3 3 3 3 3 4 3 3 3 3 4 System Requirements Collaborative Support Graphical Interface Design Validation Source Code Generation System Design Access Control Graphical Representations Petri Net Analysis Code Generation System Implementation Architecture JIVE Server JiVE Client JiVE Communication Agent Entity Representations Summary Example 4 1 4 2 4 3 4 4 4 5 4
48. bles t A Petri net is said to be live if all its transitions are live This implies that the Petri net does not contain any deadlocked states 1 e a reachable marking in which none of the transitions are enabled This Petri net is then analyzed using an external Petri net verification tool Brink 1996 The Petri net is analyzed for the following properties safeness liveness and no deadlock conditions If the Petri net has all of these properties the conversations for that system are considered coherent and logically consistent If the Petri net does not have one or more of the properties JiVE will return a message indicating to the user where the problem in the conversation might be Galan Baker 1999 When a user indicates that they would like to run the analysis the server JiVE_Server creates an instance of the PetriNetTranslator which receives as a parameter the current state of the design see Appendix B In reality this is just the Repository object which always contains the current state of the multi agent system design The PetriNetTranslator then creates the Petri net independent of the external analysis tool using the algorithm described above A class that 2 is dependent on the external analysis tool called PetriToolRepresentation which implements the PetriNetRepresentation interface facilitates this PetriToolRepresentation encapsulates the representation of the external analysis tool by providing generic methods as dic
49. cally transition whenever its start state 1s reached Specify the agent or publication channel to which a sent message goes and specify the Message Type for that message If this property is Conversation Rule Editing Window Editing Rule crnl in LogExecNet Ea Conversation Rule Name lent Customer Her Propose T SuchtThat Recenve Message Fron Message Type Push to edit suchThat Send Message To Message Type Waning Applet Window 0000 Figure A 9 Conversation Rule Editing Window left out then the conversation rule will terminate in the ending state without sending any messages For assistance in determining the relationship between agents and subscription publication channels the button labeled Subjects can be pushed This will open a window showing which agents subscribe publish to which channels and to which channels each agent subscribes publishes shown in Figure A 10 This window will additionally denote any subscription publication channels that have not been used yet faq Subscription Publication Information X Agent Agenti Subscribes Publishes To Subjecti subject Subjects Agent Agent SubscribesiPublishes To Subject Agent Agents SubscribesiPublishes To Subject Agent Agents Subscribes Publishes To Subject Subject Subject is Subscribed Published to by Agent Agent Agents Okay Figure A 10 Subscription Publication Informat
50. ccess control e Ifno other user has access control of an entity then any user who attempts an editing operation automatically receives access control to that entity e Jfa user has control of an entity then other users are prohibited from making changes In this case the users can use JiVE to request control from the user who has it That user can relinquish control or ignore the request 19 When a user logs out of the system and or the client loses the connection with the server that user relinquishes Edit Control of all entities The source code that handles access control for the entire project 1s contained in the Repository class which manages all project data See Appendix B As mentioned above there are several levels of access control and the model used for each is analogous For illustrative purposes the methods for agent edit control are presented here checkEditControlOfAgent AgentRepresentation agent User user This method is called from any place in the code where a change might be made to an agent If no one has edit control of the agent they are automatically granted the control If the user that is attempting to make the change has edit control then the change is allowed to go forward Finally if the user attempting to make the change does not have edit control then the change is cancelled requestEditControlOfAgent String agentName User userWhoWantsControl This method is called in response to a user aski
51. chapter has also covered in some cases specific details regarding the implementation of JIVE Chapter 4 will provide an example using JiVE to design a multi agent system 38 4 Example This chapter shows an example of the use of the JiVE design tool We will walk through the example implementation covering the important aspects of using JiVE This includes creating a project designing agents designing the agent conversations analyzing the conversations generating the source code making modifications to the source code and deploying the multi agent system Shown here is an example multi agent based implementation of a supply chain The JiVE User s Manual Appendix A presents a detailed description of each specific function in JiVE 4 1 Supply Chain The supply chain used in this example is a modified version of the one featured in Chauhan s thesis Chauhan 1997 which is based on the one presented by Barbuceanu and Fox Barbuceanu and Fox 1995 The supply chain consists of a Customer agent which is the agent at the end of the supply chain placing the order The Customer agent places the order with a logistics agent who must coordinate with one or more Plant agents to provide the required product 4 2 Project Initialization fea Login Window The first step to creating the JiVE project is to login to the server and create the project The User Name Alan project will be called SupplyChain and we will
52. de agents as well as agent conversations Inheritance would allow the user to design a generalized parent agent or conversation with properties applicable to an entire set of descendant agents or conversations The descendant agents or conversations would add additional specific functionality while maintaining the parent s functionality For example in a supply chain system one might have several different types of Plant agents The specification of each of those Plant agents would be faster if a generalized Plant agent could be specified and then various additional agents that inherit the Plant agent s properties are specified A Milling agent a Drilling agent and a Painting agent could be added with little additional effort Another potential place for enhancement is in the specification of the suchThat property In the current implementation the user specifies a set of method names that will be joined by a Boolean And operation in the generated source code Allowing the user to specify an extended Boolean function using method names and the various Boolean operations would improve the usefulness of this property The need to edit the JiVE generated code outside of the JiVE environment could be seen as a weakness of this tool To overcome this the incorporation of the editing into JIVE much like commercial IDEs would provide a fuller user experience The agent code could then be fully
53. defined by the user and should return a Boolean value After each of these methods returns true the conversation rule will proceed to the next state e Receive Message A MessageRepresentation object for the Message this rule will receive e Transmit Message A MessageRepresentation object for the Message this rule will transmit e Transmit Subscription The subscription or agent name to which the rule should send a message e Receive Subscription The subscription or agent name from which the rule should receive a message e Start state The starting state of this conversation rule e End State The ending state of this conversation rule e Users The user object representing the user in the system who has edit control of this conversation rule MessageRepresentation object has the following fields e Type The type of the message In JiVE this is what uniquely identifies the message e Intent The intent of the message The MessageRepresentation object does not need a user object for controlling editing access 3 4 Summary This chapter discussed the design and implementation of the JAFMAS integrated Visual Environment JiVE This multi agent system design tool uses an intuitive graphical user interface and supports a collaborative web based design environment Furthermore JiVE provides automated design validation to check the consistency and coherency of the conversations as well as source code generation regeneration This
54. dent user interfaces 1 3 Overview Chapter 2 introduces multi agent systems multi agent based design tools and collaborative programming environments and shows the relationship between JiVE and this previous work Chapter 3 then elaborates on the design and architecture of JiVE Chapter 4 presents an example design employing the JiVE software and exercising its major features Chapter 5 provides a statement of future work and improvements for the software along with conclusions drawn from this work Included as appendices are the JiVE Users Manual Appendix A the source code for JiVE Appendix B and source code generated from the example design Appendix C 2 Literature Review This chapter first presents a discussion of intelligent agents and multi agent systems It then provides a survey of tools for the design and implementation of multi agent systems The chapter concludes with a discussion of the relevant issues related to collaboration 2 1 Agents and Multi agent Systems The definition of an agent is a popular debate in the agent community There are however various terms that seem to consistently come up when defining an agent These can include intelligence autonomy reactivity and perception Huhns and Singh give a definition for an agent that reflects this ongoing debate Agents are active persistent software components that perceive reason act and communicate Some researchers add further properties such
55. e and 15 concurrency control Finally we provided a comparison of JiVE and existing collaborative applications The next chapter presents the design and implementation of JiVE 16 3 System Design This chapter discusses JiVE s design and implementation Highlighted are the important aspects for such a design tool followed by a discussion addressing these aspects We then look at the implementation details of the JiVE software starting with a higher level view of the architecture and continuing to some of the lower level details 3 1 System Requirements The desired multi agent system design tool has the following elements e Collaborative support for multiple users in a web based environment e A graphical interface for the design and visualization of the multi agent system e Automated design validation e Source Code generation and regeneration 3 1 1 Collaborative Support Having multiple users work on the same project at the same time in different locations is a very appealing notion In order to realize the goal of having multiple users there must be a mechanism to prevent two users from changing the same thing at the same time which could lead to data inconsistencies This editing control should prevent any collisions or inconsistencies while still allowing the users to collaborate effectively and be unobtrusive We not only want to collaborate on a design we would like to be able to do so in a distributed manne
56. ect allTeamF armed EE Help al Y Initial kal Initial F F Final Final GOND R Editing Conversations for Logistics Conversations for agent Logistics recieved Figure 4 6 Logistic Agent s Conversation Design 44 can move from one state to the next Therefore the conversation rules substantially specify the behavior of the system JAFMAS s representation of the order of operation of a conversation rule is as follows e The message received which enables this conversation rule and where it is received from Whether it is another agent or a subscription channel e doBefore a method that is executed before the conversation rule is executed e A set of methods that must be true in order to proceed called suchThat e doAfter a method that is executed after the conversation rule is executed e The message that is sent out because of this conversation rule being executed and where it is sent JAFMAS s doBefore and doAfter methods cannot be specified via the JIVE GUI The designer manually fills in these methods in the generated source code c f Section 4 8 The design decision to exclude the specification of these two methods in the GUI has two aspects First allowing the specification of the code in these methods through the visual environment would preclude the designer from making changes and additions to the code outside of JIVE due to JiVE s architecture Second writing code
57. ected communications that this agent has with other agents in the system We see two arrows going out to Agent3 and Agent4 and two coming in to the agent from Agent and Agent4 With this information for each agent appearing on the agent editing screen we can see the interactions between the agents but are not overwhelmed by details about the substance of those communications To view and edit an agent s properties c f Section 4 3 a dialog box can be opened Similarly to find out about or edit an agent s conversations a conversation editor window can be opened Each conversation for each agent in the multi agent system is represented by a finite state machine enclosed in a box and labeled with the conversation s name Each state in the finite state machine represents i Output conversation one possible state of the jec gt Message1 p Subje conversation and each weubjeca P transition in the finite state machine represents a means for changing conrule2 states in a conversation called a conversation rule A dot in a state denotes the starting state for the conversation A Figure 3 2 JiVE Agent Conversation Representation state drawn with a doubled line indicates a final state for the conversation Figure 3 2 for example shows an agent s conversation named Conversationl This conversation has four different states Of those four states Statel is an initial state State4
58. ed communication conversation execution and system coordination JiVE integrates with JAFMAS by allowing the designer to step through the methodology using a set of graphical user interfaces with the result being a set of generated class files that are compiled into a multi agent system JAFMAS has a unique construct carried forward into JiVE that warrants additional description Each agent in a JAFMAS based multi agent system can have a list of Required Resources These Required Resources establish the needs of the agents in the system and allow for the discovery of agents that provide that resource When the multi agent system is started the agents use multi cast messages to find the other agents in the system that provide their Required Resources 2 3 Multi agent System Design Tools There are various design tools available for the design of multi agent systems The development of these design tools range from commercially available products to research prototypes We focus first on tools that provide graphical interfaces for the development of the multi agent systems and then we mention several tools that do not provide a graphical design environment but are of particular relevance to this work 2 3 1 AgentBuilder AgentBuilder is a commercial product produced by Reticular Systems Inc it provides an integrated toolkit for the construction of intelligent agents AgentBuilder provides a fully featured set of graphical
59. ely Jacomino Geszychter and Rabelo 2000 2 3 6 JADE JADE Java Agent DEvelopment Framework is a software framework for developing FIPA compliant multi agent systems JADE provides a set of interfaces for the design of agents implemented in Java JADE uses the FIPA ACL utilizing a combination of socket RMI and CORBA This framework also provides a set of pre defined behaviors for the use of the designer including SimpleBehaviour CyclicalBehaviour and NonDeterministicBehaviour Bellifemine Poggi and Rimmassa 1999 2 3 7 KAoS KAoS is an agent architecture that provides a form of agent oriented programming A set of structures knowledge desires intentions and capabilities represent the agents in KAoS State transition diagrams specify the conversation policies Bradshaw et al 1997 2 3 0 Bond Bond is a Java based object oriented middleware for collaborative network agents It presents a set of objects to enable agent communication including Message Passing Object Replication and Directory Services The bond agents communicate using KQML B l ni 1998 A multi plane state machine represents the behavior of the bond agents B l ni and Marinescu 1999 2 3 9 Comparison of Existing Design Tools with JiVE These design tools use various approaches to facilite the design of multi agent systems Among these are some aspects that are notably similar to JIVE and other areas where JIVE impr
60. ems Themes Approaches and Challenges Readings in Agents Eds M N Huhns and M P Singh Morgan Kaufman Publishers 1998 1 23 Inamdar 1997 P C Inamdar Towards Developing Web Browser Based Collaborative Work Environments The JPECS Experience Masters Thesis ECECS Department University of Cincinnati March 20 1997 Jacomino Geszychter and Rabelo 2000 Jacomino A Geszychter M B and Rabelo R J MASSYVE Kit for the development of multi agent systems Federal University of Santa Catarina April 2000 Labrou and Finin 1998 Y Labrou and T Finin Semantics for an agent communication language Intelligent Agents IV LNAI Volume 1365 Eds M P Singh A S Rao and M J Woolridge Springer Verlag Berlin Germany 1998 209 215 Mehra and Nissen 1998 A Mehra and M E Nissen Case Study Intelligent Software Supply Chain Agents Using ADE Proceedings of the AAAI Workshop on Software Tools for Developing Agents 1998 53 62 Mills 1998 A Mills Collaborative Engineering and the Internet Society of Manufacturing Engineers Dearborn Michigan 1998 Moldt and Wienberg 1997 D Moldt and F Wienberg Multi Agent Systems Based on Coloured Petri Nets Proceedings of the 18 International Conference on the Application and Theory of Petri Nets Eds P Azema and G Balbo Toulouse France June 23 27 1997 82 101 Niemeyer and Peck 1997 P Niemeyer and J Peck Exploring Java Second Ed
61. ent by using the Java programming language Finally the generation of the source code in JAFMAS format provides the designer with a starting point for a full featured multi agent system 5 2 Discussion The design of the supply chain example presented in Chapter 4 brought forth some interesting results with regard to the design of a multi agent system that will be checked for coherency The Petri net analysis provides very strict coherency checking The downside is that it 1s not very forgiving in terms of isolating design flaws The best approach to designing a system in JiVE assuming the analysis tool is used is to build the design incrementally Starting with a smaller design that is known to be coherent and then adding incrementally will expedite the process Creating an entire project and then trying to use the analysis tool can cause the analysis to never terminate if there are numerous errors The use of the supply chain example as stated in the JAFMAS thesis Chauhan 1997 highlights another area where accommodations must be made for the analysis tool The analysis of the agent conversations with programmed constructs e g suchThat methods is often not possible 51 in JIVE JiVE s analysis can only capture information about conversation interdependencies based on the explicit communication i e messages The incorporation of additional analysis tools and formal methods may provide this added analytic flexibility c f Sect
62. er in real time or asynchronously This implies a persistence of data in the environment As part of the environment they provide various collaboration tools including user and conference management and visibility graphical editors textual editors and chat boards Roseman and Greenberg 1996 JiVE uses a similar client server architecture including user verification and a data repository though it does not incorporate any awareness features or collaboration tools beyond agent editing TeamRooms also adds an Administration client which would be an interesting expansion of the JIVE functionality c f Section 5 2 2 4 4 5 Artefact 14 Artefact is a web based tool for building collaborative applications that is itself a distributed collaborative tool It uses a client server architecture which uses HTTP as its communication protocol The are a number of base objects that a user can use to design their application as well as the ability to develop customized application objects Brandenburg et al 1998 Artefact addresses some important collaboration issues which are applicable to JiVE such as speed and performance of web based collaboration including Java but relies on a more centralized approach and a lightweight Java applet with HTTP enhancements In addition Artefact allows the user to interact synchronously or asynchronously with the application 2 4 4 6 Summary of JiVE s Relationship to Existing Groupware Systems JiVE
63. erties and messages have been added the agents themselves can be added to the design To add an agent select Agen from the toolbar or Add Agent from the Edit menu and click in the Editing Canvas This will bring up the Agent Properties window as shown in Figure A 5 In this window the particular properties that this agent is going to have are specified First the Agent Properties Window Editing Agent x Agent Name Kustomer Agent Type Hew Customer od Attributes New Required Resources Hew Customer Logistics Assembly oy Gear cane Waning Applet Window 000000 Figure A 5 Agent Properties Window name of the agent is specified Then the type of this agent is specified by making a selection on the drop down box One or more attributes that this agent can provide can then be selected Zero or more subjects can be selected to which this agent will listen Finally zero or more resources that are required by this agent can be selected in the required resource list Press Okay to submit the request to the JIVE Server A message with the results of the operation will appear in the status bar and if the operation was successful then a graphical representation of an agent will appear in the Editing Canvas The agent will look similar to those shown in Figure A 6 To edit the properties of an agent already added to the design click Agent from the toolbar
64. f the Third Annual Conference on Autonomous Agents Seattle WA May 1 5 1999 406 407 Barbuceanu and Fox 1995 M Barbuceanu and M S Fox COOL A Language for Describing Coordination in Multi Agent Systems Proceedings of the First International Conference on Multi Agent Systems July 12 14 1995 San Francisco CA Bellifemine Poggi and Rimmassa 1999 Bellifemine F Poggi A and Rimmassa G JADE A FIPA compliant agent framework CSELT internal technical report Also published in part in the Proceedings of PAAM 99 April 1999 pp 97 108 B l ni 1998 B l ni L Bond Objects a white paper Technical report CSD TR 98 002 Purdue University Department of Computer Science February 1998 B l ni and Marinescu 1999 B l ni L and Marinescu D C A Multi Plane State Machine Agent Model Technical Report CSD TR 99 027 Purdue University Department of Computer Science September 1999 Bradshaw et al 1997 J M Bradshaw S Dutfield P Benoit and J D Woolley KAoS Toward An Industrial Strength Open Agent Architecture Software Agents Ed J M Bradshaw MIT Press Cambridge MA 1997 375 418 Brandenburg et al 1998 J Brandenburg B Byerly T Dobridge J Lin D Rajan and T Roscoe Artefact A Framework for Low Overhead Web Base Collaborative Systems Proceedings of ACM 1998 Conference on Computer Supported Cooperative Work November 14 18 1998 Seattle WA 189 196
65. figuration of the systems web server is such that JiVE directories cannot be accessed the TinyHttpd web server can be installed to serve up the JiVE client files The TinyHttpd class is included with JiVE Niemeyer and Peck 1997 Please note that this web server has no built in protection mechanisms Use at your own risk Directions to start this web server are in Section A 2 1 A 2 Server A 2 1 Running the JiVE Server No matter which JiVE configuration is used Procedures for starting the server are the same Note a virtual machine for Java 1 1 x or higher must be installed in order to run the JiIVE_Server In Windows type the following at a command prompt from the installation directory A3 start java JiVE JiVE_Server On a Unix machine type the following from the installation directory java JiVE JiVE_Server amp If it is necessary to run the included web server type the following as well for windows Start java TinyHttpd lt port_number gt Or for Unix java TinyHttpd lt port_number gt amp Where lt port_number gt is the port on which the web server will run e g 9999 A 2 2 Adding New Users To add a new user to the list of possible users in the system open the Users txt file located in the JIVE subdirectory in a text editor and add the person s user name and password separated by white space on a new line before the line with EOF A 3 Client A 3 1 Running the Client Applet To run the client load the
66. for just one method in the visual environment would not give the designer the needed flexibility to implement cohesive code Some code is automatically included in these methods relating to the communications as specified in JIVE This code should remain and user defined code can be added to the appropriate part of the method This section shows the design of a conversation rule specifically in the Logistics agent in the LogExecNet conversation 45 We will create the conversation rule Conversation Rule Editing Window Editing Rule lenb in LogExecHet Fa named len6 which connects the Conversation Rule Name len FormingLargeTeam state to the Recenve Message From Logistics Fail state shown in Figure 4 6 We see in Figure 4 7 that the name Message Type Newy Reject is specified The enabling message Push to edit suchThat suchthat can come from either a subscription eu channel or a specific agent Figure SEUSS ie Uit Customer x 4 8 shows the drop down menu ese ma Ree 7 which lists the possible choices for the sender and or recipient of a okay Clear Cancel Subjects R particular message First are listed Waring Applet Window O OO the possible subscription channels followed by the agents in the Figure 4 7 LogExecNet Conversation Rule Design system In this case we chose for the enabling message to come from The Logistics agent with a message type of Rejectl
67. iVE additional functionality can be added to the source code if desired In some cases there is some code that needs to be added in order to compile and deploy the multi agent system A16 To add additional functionality to the JiVE generated source code it is important to note that any editing that is done between the opening double brackets and closing double brackets will be deleted upon regeneration of the source code For example System defined fields Do not edit Any additions in here will be deleted EL ys Any additions out here will remain The only required additions are the suchThat methods if they exist If suchThat methods are specified in the multi agent system design in any of the conversation rules then the corresponding method definition will have to be added to the generated source code In most cases additional functionality will be added beyond that The doBefore and doAfter methods which are included in the automatically generated source code can be filled in if desired by the user This would be the location to do any operation or call any methods that should be done before or after the operation of the conversation rule These methods can be found in the classes for each conversation rule A 5 2 Compiling the JAFMAS Source Code To compile the JAFMAS Source Code place all of the JAFMAS files along with all of the JiVE generated files into the same directory Execute the following javac
68. ic with a significant amount of research behind it This research generally falls under the title Computer Supported Cooperative Work CSCW The implementation of CSCW concepts is usually termed groupware Groupware applications improve the ability of a group to produce results by allowing them to collaborate and more importantly to be an active participant in a distributed design environment Mills recognizes a future for groupware applications specifically in Collaborative Engineering due to the high return on investment and improving Internet standards Mills 1998 This section discusses the requirements for CSCW tools or groupware There is also a discussion of issues involving the architectures needed A section on the concurrency of data in these tools follows that We then provide several examples of specific groupware applications and conclude with specific comparisons to JiVE 2 4 1 Requirements Some methods by which requirements for groupware applications are established are outlined in Ehrlich 1999 and summarized in this subsection 2 4 1 1 Work Practices Work practices refer to the way in which a user of an application utilizes that tool in real life situations The development of a collaborative work environment or any application for that matter should of course consider this A realization is needed that designing an application should keep the needs of the user in mind Furthermore Hughes et al 1996 suggests that the
69. icating the success or failure of adding the conversation rule Upon success a directed line appears in the Conversation Editing Window between the appropriate states When the user desires more information on a conversation rule the rule can be expanded to view all of its properties by selecting lt Rule from the toolbar or selecting Edit Conversation Rule from the Edit menu and then by clicking on the conversation of interest Other conversation rules can be added to the design in a similar manner When the conversation s design is complete the conversation design window can be dismissed by selecting Close Window on the Close menu A14 A 4 5 Analyzing Conversations and Generating Code Once the entire design is completed the system can be analyzed for coherency and the JAFMAS source code can be generated The analysis of the conversations is as easy as selecting Analyze Conversations on the Tools menu During analysis no changes to the design are permitted In addition the analysis can take some time depending on the intricacies of the design and the processing power of the machine in use When the results are returned an alert will be provided concerning any problems in the design These alerts will help track down any errors in the design When the errors are fixed and the analysis is run again it returns a message stating that are conversations are ready to go which means that the source code
70. in designing a collaborative environment is to control the changes that various users can make JiVE attempts to control this with as little intrusion as possible In many cases the system handles access control automatically In other cases the user has to manually request control from another user who can relinquish that control at their leisure JiVE has built in mechanisms for this request relinquish scheme One way to accommodate multiple users working on the same project collaboratively would be to limit editing access of the whole project to one user at any given time This approach does not provide the flexibility desired for JIVE Instead we use a more fine grained access control model This means that access control is applicable at several different levels namely e Agent Edit Control e Conversation Edit Control e Conversation Rule Edit Control That means that any one user can have a lock on any one of the entities listed while other users can have the editing control for other entities For example Userl could have control of Agentl while User2 could have control of Conversation which may be a conversation of Agentl Of course when any user in the system makes a change to any part of the design this change is visible to every other user in the system The automated access control follows the following rules e As auser adds any controlled entity to the system they automatically get a
71. index html file in the JiVE installation directory in a Java 2 compatible appletviewer or web browser As of this writing the major web browsers were just beginning to support the Java 2 platform so we recommend the use of the Java 2 appletviewer If the server is using a standard web server the user would type appletviewer http lt server_url gt lt InstallationDirectory gt index html If the server is using the TinyHttpd web server type appletviewer http lt computer_name gt lt port_number gt index html If the server is going to run just on the local file system change to the directory where the files are located 1 e the JiVE installation directory and type appletviewer index html A 4 Using JIVE This section describes the use of JIVE for the design of a multi agent system It steps through the use of JiVE from the initialization of a project through the adding and editing of agents A4 conversations and conversation rules and finishing a project using the built in design analysis and code generation tools The section finishes by describing JiVE s collaborative aspects A 4 1 Starting Off The first step to working on a multi agent system design in JIVE is starting the client and opening a project Upon first opening the JiVE_CTient applet a login window appears as shown in Figure A 2 From this login window a user can create a new project or load an existing project The login window has two modes New
72. ion 5 3 3 At this point systems designed in JiVE assuming the analysis tool 1s used must refrain from defining the conversations in terms of programmed constructs In addition to the inability to analyze programmed constructs in the suchThat methods users must be cautious in their use of the doBefore and doAfter methods so as not to introduce programmatic control of the conversations Finally the growth of the Petri net 1s an issue that may be prohibitive for some larger designs The Supply chain example appeared to be on the edge of what could be analyzed in JiVE This could be because of the use of a shareware Petri net analysis tool Petri Tool Brink 1996 where optimizations in speed are still possible The designer should be aware that the size of the Petri net associated with a particular multi agent system design can grow large very quickly and thus drag analysis to a halt This is especially true for certain constructs such as messages that are sent to multiple agents simultaneously Given more computing power and improved Petri net analysis tools this issue does not seem to invalidate the general usefulness of Petri net tools in evaluating the coherency of multi agent systems 5 3 Future Work and Enhancements 5 3 1 Improved Collaboration features Several features would add value to the collaboration features of JIVE A white board and chat feature in which the various users logged on to the design environment could communicate
73. ion Window A13 The additional property that is set from this Edit methods for suchThat x interface is the set of suchThat methods This is the set of methods which must be true for the Poo conversation rule to transition Note Multiple methods are evaluated using a Boolean And cannotRanke antractors operation To specify the suchThat methods press the button labeled suchThat and a window will open like the one shown in Figure A 11 For each method type the name in the text field at the top and press Add The name of the Okay Cancel window Each method name must be a valid Java wating Applet wWindow method is moved to the list on the bottom of the method name To remove a method name select p gure A 11 Such That Design it in the list on the bottom and press Remove The method name is removed from the box When finished specifying the methods for this conversation rule s suchThat property press Okay The doBefore and the doAfter methods are not specified via the JiVE GUI It is instead left to the designer to fill in those two methods in the generated source code as desired c f Section A 5 1 Upon full specification of the conversation rule the request can be submitted to the server by pressing Okay on the Conversation Rule Design Window The window will disappear and a message from the JiVE Server will appear in the status bar ind
74. ition O Reilly amp Associates Inc Sebastopol CA 1997 Nissen and Mehra 1999 M E Nissen and A Mehra Some Intelligent Software Supply Chain Agents Proceedings of the Third Annual Conference on Autonomous Agents Seattle WA May 1 5 1999 374 375 60 Nwana et al 1999 H Nwana D Ndumu L Lee and J Collis ZEUS A Toolkit for Building Distributed Multi Agent Systems Applied Artificial Intelligence Journal Vol 13 1 1999 129 186 Parunak 1996 H V D Parunak Visualizing Agent Conversations Using Enhanced Dooley Graphs for Agent Design and Analysis Proceedings of the Second International Conference on Multi Agent Systems ICMAS 96 Kyoto Japan December 10 13 1996 Patterson Day and Kucan 1996 J F Patterson M Day and J Kucan Notification servers for synchronous groupware Proceedings of the ACM CSCW 96 Conference on Computer Supported Cooperative Work Boston MA November 16 20 1996 122 129 Peterson 1981 J L Peterson Petri Net Theory and the Modeling of Systems Prentice Hall Englewood Cliffs New Jersey 1981 Prakash 1999 A Prakash Chapter 5 Group Editors Computer Supported Co operative Work Ed M Beaudouin Lafon John Wiley amp Sons West Sussex England 1999 103 133 Ressel Nitssche Ruhland and Gunzenhauser 1996 M Ressel D Nitsche Ruhland and R Gunzenhauser An Integrating Transformation Oriented Approach to Concurrency Control a
75. kditor Window This dialog box is opened when the user tries to add or edit a message type in the system Itis opened from the JiVE_Client window RemovePropertyWindow This dialog box display a drop down box allowing the user to remove an item from the select property This is opened from the JiVE_Client window StatePropertyEditor This dialog opens when the user adds a state to a conversation allowing the user to specify the name of the new state It 1s opened from the ConversationEditor Table 3 2 List of Dialog Boxes and Their Functions 32 change appropriately and responds to the client s If the editing change 1s successful the server will send a message out to all of the clients notifying them of the change including the original editor If the editing change is not successful then the server will notify the user who attempted the change of why the change was not successful The ClientCommunicator handles these incoming messages and passes them to the proper GUI screen for display to the user Part of the creation of a new project requires the user to specify the agent communication language that their multi agent design will use The default or Standard language selection in JiVE utilizes a subset of the JAFMAS Message class This means that the designer must specify their own set of messages for their specific application JIVE requires the user to specify the type of each message and optionally the intent of
76. le 5 3 6 Improved ACL Support The current support in JiVE for the ACLs is limited to allowing the designer to specify a set of standard performatives for the system communication Support for ACLs could be enhanced allowing for adding standard ACL protocols and additional coherency checking In certain ACL specifications there are standard protocols defined for example FIPA ACL FIPA 1997 These protocols provide functionality such as query contract net and English auction The ability to add these and other pre defined protocols to a multi agent design in JIVE would greatly decrease the design time and improve the functionality The coherency checking outlined in this thesis cf section 3 2 3 could be supplemented by checking the correctness of the use of the ACLs For example if the user has specified for an agent to receive a message with the performative of Ask it could be verified that the agent responds with Tell These defined semantics of the ACL provide a guide for how the agents communicate and would be useful as an additional coherency check 5 3 Improvements in Agent Design 55 JiVE has been closely coupled with JAFMAS which provides a basis and a framework for implementing multi agent systems Although this has affected the JiVE implementation in content and structure it would be possible to move to a more general approach where the user would have the choice of various agent frameworks to design against
77. le at http www csh rit edu rick thesis thesis html Chauhan 1997 D Chauhan JAFMAS A Java Based Agent Framework for Multi Agent Systems Development and Implementation Masters Thesis ECECS Department University of Cincinnati July 16 1997 Available at http www ececs uc edu abaker JAFMAS index html FIPA 1997 FIPA Part 2 Agent Communication Language FIPA 97 Specification Foundation for Intelligent Physical Agents Geneva Switzerland November 28 1997 Available at http drogo cselt stet it fipa f7a12 zip Galan 2000 A Galan JiVE JAFMAS integrated Visual Environment Masters Thesis ECECS Department University of Cincinnati 2000 Available at http www ececs uc edu agalan Ji V E index html Labrou and Finin 1998 Y Labrou and T Finin Semantics for an agent communication language Intelligent Agents IV LNAI Volume 1365 Eds M P Singh A S Rao and M J Woolridge Springer Verlag Berlin Germany 1998 209 215 Niemeyer and Peck 1997 P Niemeyer and J Peck Exploring Java Second Edition O Reilly amp Associates Inc Sebastopol CA 1997 A18
78. ls including Agent Builder ZEUS and DECAF Others directly deploy the agent based system including ADE MASSYVE Kit KAoS and Bond The generation of source code allows the users to add behavior to the agents after using the tool for the basic design where a direct deployment prohibits this However using direct agent deployment the design tool can better control the final system albeit at the expense of flexibility JiVE is the only design tool available to support multi agent system design and development in JAFMAS All of the design tools are very tightly integrated with their own underlying multi agent framework JIVE however has the ability to incorporate other frameworks then JAFMAS by replacing the Code Generation module Additionally JiVE is the only tool that supports multi user development and a web based interface Collaboration Graphical Design Implementation Java Pricing Support Design Validation Support She Based Environmen t A E AgentBuilder en A ADE ZEUS oo DECAF o MASSYVE JADE o Kaos Bond o Table 2 1 Comparison of JiVE with Exisiting Multi System Design Tools Le C Code generation D Direct deployment t F FIPA ACL K KQML G General speech act based messaging F Freeware Free for most non commercial uses 10 ADE is a commercial development environment sold bundled with services 2 4 Collaboration Collaboration of multiple users is an interesting top
79. n Design Window conversations in which the agent can engage The second entities in the Conversation Design Window are the states labeled circles within a conversation rectangle see Figure A 8 The states represent the possible states of execution that a given conversation can be in at any one time Each conversation will have multiple states The final entities in the Conversation Design Panel are the conversation rules A conversation rule represented as a directed line Input Conversation connects two states The arrow points Eee Messages Sy T e from the beginning state to the ending state of the conversation rule The design of conversation rules is discussed in Section A 4 4 A 4 3 1 Adding and Editing Conversations To add a conversation select fromthe Figure A 8 Conversation Representation Conversation Design Panel toolbar A10 oConv or Add Conversation from the Edit menu and then click and drag drawing a rectangle on the Editing Canvas drag from the top left to the bottom right of the rectangle A window will appear allowing the name of the conversation to be typed Press Okay to submit the request to the JiVE Server The JiVE Server will return a message displayed in the Status Bar indicating the success or failure of the operation If successful a labeled rectangle with a side bar on each side will appear on the Conversation Design Window s Editing Canvas i l l t mnie rv
80. nd Undo in GroupEditors Proceedings of ACM 1996 Conference on Computer Supported Cooperative Work Boston MA November 16 20 1996 288 297 Reticular 1999a Reticular Systems AgentBuilder An Integrated Toolkit for Constructing Intelligent Software Agents Reticular Systems Inc February 18 1999 Available at http www agentbuilder com Documentation white_paper_rl_3 pdf Reticular 1999b Reticular Systems Using Intelligent Agents to Implement an Electronic Auction for Buying and Selling Electric Power Reticular Systems Inc August 30 1999 Available at http www agentbuilder com Documentation EPRI epri pdf Roseman and Greenberg 1996 M Roseman and S Greenberg TeamRooms Network Places for Collaboration Proceedings of ACM 1996 Conference on Computer Supported Cooperative Work Boston MA November 16 20 1996 325 333 61 Ygge and Akkermans 1997 F Ygge and H Akkermans Making a Case for Multi Agent Systems Multi Agent Rationality 8 European Workshop on Modeling Autonomous Agents in a Multi Agent World MAAMAW 97 Ronneby Sweden May 13 16 1997 Eds M Boman and W Van de Velde Springerman 1997 62 Appendix A JIVE Users Manual This appendix contains installation procedures and directions for using JiVE There are instructions for starting the client and server portions of the software as well as instructions for using the client s Graphical User Interfaces A 1 Installati
81. nerated by JIVE based on the design in our project needs several additions before it can be deployed as a multi agent system First it is important to note that even after making changes or modifications to certain areas of the source code it is still possible to change the conversation designs and regenerate the source code There are lines in the source code that look like this Pra JiVE Generated Code is here eae These lines delimit the area of the source code which is generated by JIVE As long as the user does not add or edit any text within those areas their code will remain intact 49 The first thing that needs to be added to the source code before we can even compile it are any methods we specified in the suchThat property The different methods can be located by compiling the source code which will generate an error message pointing to each suchThat method that has not been elaborated These methods should return a Boolean value and can take no parameters There are no restrictions on what these methods can contain They should however indicate by returning true or false whether a conversation that checks its status can complete its transition The methods doBefore and doAfter which are included in the automatically generated source code can be filled in if desired by the user This would be the location to do any operation or call any methods that should be done before or after the operation of the convers
82. ng for edit control of an agent If no other user has the edit control than the control is granted to the requester otherwise a message is sent to the user who does have control asking him to relinquish it relinquishEditControlOfAgent String agentName User userWhoHadControl This method is called in response to a user relinquishing edit control of the agent 3 2 2 Graphical Representations In order to draw a multi agent system in a graphical manner we need to intuitively represent the agents and their conversations In JiVE a a Agent rectangle on the Agent editing screen represents agents the agent This rectangle lists the name of the 2 agent and an expand icon along with the agen number of intended subscription publication l e Subject gen Subject 11H 1m 10uT channels When expanded one can see the Subjects relationship between the agent and the various subjects with which it communicates For Figure 3 1 JiVE Agent Representation example in Figure 3 1 we see a depiction of an 20 agent This agent s name is Agentl The subjects that it subscribes to and or publishes to are listed below it on the expanded listing We can see that Agentl receives messages on the Subjectl subscription channel sends messages on the Subject2 publication channel and both sends to and receives from the Subject3 subscription publication channel Also noted in this graphic are the dir
83. ntaining the source and class files for the Petri net analysis tool PetriTool is also a sub directory of the installation directory There is also a directory Figure A 1 Directory Structure created that contains all of the individual project A2 files including the files used by JiVE and the JAFMAS Source code generated for each project A 1 3 Standard Configuration The standard configuration of JiVE assumes access to a web server and the desire to utilize the collaborative features There are instances where it may not be possible to use this configuration due to the specific web server in these cases follow the directions in Section A 1 5 Install the JiVE directory structure into a directory that can be accessed via a web server Once the files are in place the JiVE_Server can be started c f Section A 2 1 and users will be able to access the JiVE index html file which is in the JiVE installation directory This starts the JiVE_Client in the web browser and allows for login to a project c f Sections A 2A 3 A 1 4 Free Standing Configuration This configuration allows the use of JIVE if there is no access to a web server This configuration will not allow the use of the collaborative features Install the JIVE class files in any directory location and run the JiVE_Server and the JiVE_Client on the local machine from the JiVE installation directory c f Sections A 2 and A 3 A 1 5 TinyHttpd Configuration If the con
84. ntrol That means that any one user can have a lock on any one of the entities listed while other users can have the editing control for other entities For example Userl could have control of Agentl while User could have control of Conversation which may be a conversation of Agentl Of course when any user in the system makes a change to any part of the design this change is visible to every other user in the system The automated access control follows the following rules e As auser adds any controlled entity to the system they are given access control automatically e Ifno other user has access control of an entity then any user who attempts an editing operation automatically receives access control to that entity e Jfa user has control of an entity then other users are prohibited from making changes In this case the users can use JiVE to request control from the user who has it JiVE prompts the user with control with a dialog box That user can relinquish control or ignore the request e When a user logs out of the system and or the client loses the connection with the server that user relinquishes Edit Control of all entities A 5 Multi Agent System Deployment This section outlines the method to create and deploy the multi agent system once JIVE has been used to design check and generate code A 5 1 Adding Additional Functionality After automatically generating the source code with J
85. of these lines Some examples of this are to not allow two conversation rules to overlap or allowing the user to route the conversation rule manually using more than one vertex This improved routing of the conversation rules would also open up improvement to the conversation rule selection model Currently a user must select the starting state and ending state of any conversation rule that they would like to add edit or delete One click could be removed for editing and deleting this would make JiVE easier to use 5 3 3 Improved Efficiency During Design The efficiency of using this multi agent system design tool could be improved by adding the following features First an ability to reuse conversations or parts thereof that have already been designed Ideally this would be a copy and paste operation where the user could select a conversation indicate a cut and reuse that conversation in another agent s conversations This would be especially useful in designs where different agents have similar conversations In addition the ability to create nested conversation structures would greatly improve the ability to 53 create a multi agent system in JIVE JAFMAS has facilities to support a nested conversation model but these are not supported in JiVE therefore the designer must manually incorporate nested conversations Providing mechanisms for utilizing inheritance would also greatly improve the JiVE design experience This could inclu
86. on The JiVE software can be installed in several different ways depending on the specific system and intended use This section first discusses the minimum system requirements the JiVE file structures and then the three configuration options A 1 1 Minimum System Requirements The minimum systems requirements for the server and the client are slightly different The server is written such that it is compatible with the Java Development Kit Version JDK 1 1 x The server needs a JDK 1 1 x runtime engine and optionally a web server and or Internet or network connection The client classes use the Java Swing package which is part of Java 2 i e JDK 1 2 The client is an applet and therefore needs to be able to run a Java 2 applet that is either a Java 2 appletviewer or a Java 2 compatible web browser as of this writing the major web browsers were just beginning to support Java 2 The processing power of the machines used to run both the client and the server can become an issue for certain older machines Although less processing power will not generally cause a problem in using JIVE there are situations where ample processing power is required Specifically the analysis preformed at the server can be especially computationally intensive Here the size and complexity of the design strongly effects speed Sections A 1 3 through A 1 5 discuss the three installation options for JiVE They refer to the client files and the server files listed
87. on Rules and Messages The class names respectively are AgentRepresentation ConversationRepresentation ConversationRuleRepresentation and MessageRepresentation Each Representation has several common properties First and most important for JiVE operation each Representation implements the Java Serializable interface This allows these objects to be turned into a serial stream which can then be sent over a communication channel in this case the TCP IP Sockets This makes sending any information about these agents as simple as writing the object to the stream Each of these Representations also encapsulates the information about how they are written to a file This is implemented as a toString method in each class Additionally each Representation object contains the information about which user if any has access control of it This information 1s a User Object For example to check the edit control of an AgentRepresentation object called agent we can just call a method to find out who currently holds the access control User userWithControl agent getUserWithEditControl Then we can compare the userWithControl object with other User objects to determine who has or will get edit control of that entity The agent s properties represented in the AgentRepresentation object and summarized in Figure 3 8 are as follows e Agent Name The agent s name e Attributes Zero or more attributes th
88. on on ACLs in JiVE see Galan Galan 2000 In addition to naming the project and selecting the desired language type type the User Name and Password into the login window and then press Okay The JiVE_Server will validate the A5 login data and upon verification the Multi Agent System Design Window will open This is where the properties and agents for the multi agent system will be specified A 4 1 2 Existing Project To open an existing project select Exist Project from the login window enter the User Name and Password select the project to be opened from the pull down menu and then press Okay The JiVE_Server will validate the login data and upon verification the Multi Agent System Design Window will open This is where properties and agents for the multi agent system will be specified and edited A 4 2 Designing the Agents The Multi Agent f JAFMAS integrated Yisual Environment JYE File Edit EditControl Tools Help System Design Window is where the agents and e the agent s properties a oe Subject are added shown in aSubject ribute Figure A 3 Emad midtribute A 4 2 1 Adding And ING ANC nttessaue agent Removin g wAgent Agent Properties Pro pe rties E Request Edit Control Agent Relinquish Edit Control Status Bar Popup Menu The first step is to add the agent s properties a IN al ele Gale These properties are the pe pel added by System
89. onversation rules connected to that state will also be deleted Additionally states may be moved within their conversations by clicking and dragging the state A conversation must have an initial state and one or more final states An initial state means that when the conversation starts it is in that state and is indicated by placing a token a black All dot in the state A final state means that upon reaching that state the conversation terminates Doubling the line that comprises the state indicates a final state The initial and final status of each state can be toggled with the following procedure For example to make a state initial select J Initial fom the toolbar or Mark State As Initial from the Edit menu and click on the state which will be marked as an initial state The server will respond with a message indicating any changes made This same procedure is applicable to Mark State As Final y Final Unmark State As Initial J Initial and Unmark State As Final y Final After the various conversations and states have been added to the Conversation Design conversation rules can then be added to the conversation A 4 4 Designing the Conversation Rules The conversation rules in a conversation indicate to the system the operations that must be done for an agent s conversation to transition from one state to the next In JAFMAS the order of execution of a conversation rule is as follows
90. or select Agent O IH 1e oourt Agenti e Subject Edit Agent from the Edit menu and Subject2 1N 1M 61 0UT Agenta Agent4 Se Subjects then select the agent to be edited or right click on the Agent and select Figure A 6 Agent Representation AS Agent Properties from the popup menu The Agent Properties window will open and the agent s properties can be edited Except for the agent s name which must stay the same Continue to add agents to the design in this way A 4 2 4 Agent Representation In JIVE a rectangle on the Agent editing screen represents the agent This rectangle lists the name of the agent and an expand icon along with the number of intended subscription publication channels When expanded one can see the relationship between the agent and the various subscription publication channels with which it communicates For example in Figure A 6 we see a depiction of an agent This agent s name is Agentl The subscription publication channels that it subscribes to and or publishes to are listed below it on the expanded listing We can see that Agentl receives messages on the Subject1 subscription channel sends messages on the Subject2 publication channel and both sends to and receives from the Subject3 subscription publication channel Also noted in this graphic are the directed communications that this agent has with other agents
91. oves on the current collection of work JiVE like many of these other design tools has turned to Java to provide platform independence This choice affects the deployment of the design tools themselves as well as the systems that these tools design JiVE is both written in Java and produces Java based multi agent systems Many of the design tools listed support the standard ACLs either KQML AgentBuilder Zeus and Bond or FIPA ACL JADE JiVE which supports the use of both ACLs combines ACL support with the ability to have user defined communication languages JiVE uses a similar representation for the agent communications as many of the other tools Various tools use state machines Petri nets or variations thereof to specify the agent communication The multi plane state machine used in Bond is an interesting expansion of the traditional state machine representation Checking the conversation models for consistency and coherency is not a feature that many design tools have although DECAF does have some design time error checking and ADE provides some simulation and debugging capabilities JiVE on the other hand has an algorithm for converting the agent communication representations to a Petri net for analysis of consistency and coherency of the systems communications The generation of source code for the deployment of the multi agent systems is another important aspect of JIVE which is included in some of the current design too
92. r This type of distributed collaboration will have an impact on the architecture used for the software tool In addition we will need to provide facilities for communication connections 3 1 2 Graphical Interface The first and arguably the most important aspect of designing a multi agent system design tool is the graphical representations used to denote the different entities in the system as well as the layout and design of the graphical user interfaces 17 The graphical interface that the development environment employs should make the design of a multi agent system intuitive and provide a premium of information to the designers without making it too difficult to understand and or find the information The information conveyed by the graphical representations of the agents and their conversations should allow the user to see at a glance the basic interactions and properties in the system When desired by the user there should be a mechanism for getting more information about any one piece of the design The layout of the graphical user interfaces should also be intuitive to the user Buttons and messages should be easy to understand and help access should also be easy Additionally the user should be able to see the status of the design process at any given time 3 1 3 Design Validation The conversations of a multi agent system dictate the behavior of the system In order to ensure that the multi agent system will exhibit the desi
93. r agent Customer f E ioj x Close Edit Edit Control Help F Propose b Logistics Output oe Messages a Initial Initial Final Final zetett ym z Help Editing Conversations for Customer Conversations for agent Customer recieved Figure 4 5 Customer Agent s Conversation Design 42 agent Each agent can have one or more conversations the design panel shows all conversations with each conversation denoted by a labeled rectangle To each side of the labeled rectangle are summaries of the input and output messages Clicking the triangle on the right side of each summary entry will provide a menu with links to each referenced conversation To add a conversation we select Conv from the toolbar or Add Conversation from the Edit menu on the menu bar We click and drag on the Conversation Design Panel which prompts us to specify the name of the conversation in the case of Figure 4 5 the name of the conversation 1s CustomerConversation With the conversation placed on the panel we can begin adding the elements of the conversation including the conversation states and the conversation rules To add each state in the design select Add State from the menu bar or S te from the toolbar and place the state in the conversation We can specify the name of the state as well as whether it is an initial state a final state both or neither These properties can be changed as we progress
94. rcs are constructed from each of the transitions in the previous step to the place added 1n this step This represents the 26 corresponding conversation reaching a final state When the place added in this step contains a token that conversation has reached a final state e One more transition is added for the entire conversation set which corresponds to all of the conversations reaching a final state and then resetting each conversation to their initial states An arc is added from each place added in the previous step to the transition added in this step One arc 1s added from the transition in this step to each place which is marked as an initial state thus resetting the Petri net e Finally one token is added to each place that corresponds to an initial state Having built the Petri net from the original conversation model we can analyze the multi agent system for coherency There are several properties of a Petri net that are required in order to consider that conversation model coherent Peterson 1981 The Petri net must be safe We consider a place safe if for all possible markings the number of tokens in that place never exceeds one Furthermore we consider the Petri net safe if all of the places in it are safe The Petri net must also be live A transition t of a marked Petri net is said to be live under a marking Mo if for all markings M e R Mo there exists a sequence of transition firings which results in a marking that ena
95. red system level behavior one must ensure that the interactions between agents are consistent with the goals of the system This means that the conversations that an agent can engage in must be logically consistent and coherent Therefore it is necessary to specify the conversations in such a way that we can prove for the entire system the consistency and coherency So our multi agent system design tool shall include conversation analysis techniques The results from this analysis should help guide the user on how to fix any logical errors in their design This type of validation will help the designer in creating a multi agent system that achieves its desired goals Galan Baker 1999 3 1 4 Source Code Generation Once the multiple distributed users have created a multi agent system and have checked the design for logical consistency the next step is to assist them in the implementation The design tool should be able to take the specified agents conversations and properties and translate them directly into usable source code This source code may need manual supplementation but the designers should have a solid starting point for enhancing their design Additionally there should be support for regeneration of the source code to accommodate design changes even after the designer has made manual modifications 18 3 2 System Design This section outlines how JiVE meets these requirements 3 2 1 Access Control An important aspect
96. requests are serialized such that there will be no inconsistencies in the data The downfalls of this type of centralized system include the server being a computational bottleneck and network latency Replicated architectures have no centralized server and respond to changes in state locally and send information to each other in order to update the other s data With a distributed system the cost of a replicated architecture is a more complicated system There is also now a need for distributed concurrency control Some benefits of this approach are a decrease of the computational bottleneck due to the server and less chance for latency due to the diminished amount of data transferred The compromise in many cases is a hybrid architecture incorporating centralized and replicated features in an attempt to gain the best of both worlds Patterson Day and Kucan discuss an example of this type of architecture Patterson Day and Kucan 1996 They talk of an architecture that has a central server that acts as a repository for the shared system data and handles any changes for the clients The clients however control the data locally and manage 12 their own view of the data JiVE uses this hybrid approach to its architecture but leans towards a centralized approach c f Section 3 3 2 4 3 Concurrency An important aspect of designing a groupware application is the concurrency of the data in the application Prakash suggests two broad clas
97. rk in the Computer Supported Collaborative Work research area to provide an application that allows designers whom are not co located to design a multi agent system together JiVE handles all of the issues of concurrency and design consistency and provides an easy to use collaborative environment Furthermore JiVE provides a unique set of features for a multi agent system design tool Commonly used techniques in multi agent system design and collaborative computing such as web based collaboration agent communication languages and a fully featured Java based Graphical User Interface are combined in JIVE This distinct combination of features makes JiVE stand out among the existing multi agent system design tools This thesis presents the research related to the application of the JiVE software along with descriptions of its design and implementation A supply chain example exercises the software conclusions are drawn and we suggest future improvements and enhancements Acknowledgments I give my thanks and appreciation to Dr Albert Baker for his assistance and guidance in the preparation of this thesis I also owe my gratitude for his continuing support in my academic and professional pursuits My thanks go to my thesis committee Dr John Franco Dr Ali Minai and Dr Marios Polycarpou who have made the completion of this thesis possible I would also like to thank my parents for their undying love and support from beginning to end They h
98. rther enhances this model Chauhan 1997 to include a Petri net representations taken from the individual conversations aggregating them into one specification Moldt and Wienberg present a representation of multi agent systems based on Colored Petri nets Moldt and Wienberg 1997 The tokens in the CPN represent the dynamic components of the complex system They further make the distinction between the agent society and the agent both of which use Petri nets as representations Cost et al have also used Colored Petri nets Cost et al 1999 They claim that the use of these CPNs allow for improved support of concurrency and complex interactions In contrast Parunak presents an enhanced form of the Dooley Graph Parunak 1996 The Enhanced Dooley Graphs are said to be useful in capturing agent interactions and expressing them in an easy to understand manner The Z specification language has also been proposed as providing a framework for describing multi agent interaction d Inverno Kinny and Luck 1998 2 1 2 Agent Communication Languages The agent communication languages ACL used in multi agent systems are another important aspect of the design of a multi agent system An ACL 1s a precisely defined protocol for inter agent communication in multi agent systems including syntactic and semantic definitions The two ACLs that seem to be in the forefront of acceptance as standards are KQML and FIPA ACL KQML is a message format as well as a
99. s collaboration features draw from existing work on groupware systems JPECS and JSIM provide much of the basis for JiVE s collaborative architecture messaging and user control Concurrency control components of Joint EMACS are similar to JiVE although more fully developed In terms of architecture JIVE TeamRooms and Artefact are similar in their client server configuration In addition Artefact provides a thorough approach to web based collaboration from which future versions of JiVE could draw All of the tools mentioned in this section have various collaboration tools that could supplement JiVE s collaboration experience 2 5 Summary This chapter discussed some of the current literature in the fields related to this thesis The chapter started with some background on agents and multi agent systems Specifically addressed were the communications between agents including the basis for JiVE s representation of conversation and conversation rules and the use by JiVE of ACLs The presentation of the existing work in the area of multi agent design tools highlighted the unique approach JIVE takes on this issue The distributed collaboration features of JIVE are one of the things that make it stand out The existing work in collaborative software provides the bases for these features This includes the requirements for a groupware application and some design methodologies We also showed how JiVE relates to existing work in terms of architectur
100. ses of concurrency control in a group editor Prakash 1999 Pessimistic concurrency control refers to the method of acquiring network wide locks before allowing the editing of a document or section of the document which incidentally is the method used by JIVE This method can slow the rendering of the local data in cases where the lock has to be acquired Optimistic Concurrency Control allows any changes on the local copy of the data to be effective immediately and then sends that information over the network including a time stamp to be reconciled with all of the other users When this information is reconciled with the operations in each client there may be a need to roll back or undo operations This method requires that operations be reversible in order for the reconciliation at each client In addition there is the opportunity for the users to interact with inconsistent data 2 4 4 Example Groupware Systems 2 4 4 1 JPECS JPECS Java Programming Environment with Collaborative Support 1s a web based platform independent collaborative work environment It provides a platform for the distributed editing and simulation of a visual programming language in this case a finite state machine simulator including a whiteboard and chat feature It deals with issues such as concurrency multi user communication and collaboration Inamdar 1997 JPECS provides a basis for JiVE s collaborative features JIVE utilizes a similar approach in terms
101. sh Agent Edit Control Edit Control Menu Tools Menu o Request Conversation Edit Control o Check Conversations o Relinquish Conversation Edit Control o Compile Code o Request Conversation Rule Edit Control o Refresh Project o Relinquish Conversation Rule Edit o Expand Collapse Subscription Info Control Help Menu Help Menu o Getting Started o Getting Started o Help o Help o About o About Table 3 1 List of JIVE Menu Items e Editing Canvas The editing canvas is where the graphical representations of the agents or conversations are located This is where the user would interact to add delete or edit any entities in the design e Popup Menu This is another way for the user to select applicable commands This menu will show the applicable commands according to where in the Editing Canvas the user has clicked In Figure 3 3 the user has right clicked on Agent1 and is presented with several possible commands Delete Agent Edit Agent Properties Edit Conversations Request Control and Relinquish Control 25 3 2 3 Petri Net Analysis As was discussed in Section 3 2 1 we specify the conversations and conversation rules of the multi agent system using a finite state machine representation This representation allows for Petri net Peterson 1981 description of the conversations which then allows for the validation of the design Chauhan 1997 The conversion of the finite state machine into a Petri net is as follows
102. tated by PetriNetRepresentation to create a Petri net and then converting that Petri net information into the proper format This construction allows for the replacement of the external analysis tool A new class implementing the PetriNetRepresentation interface could be written for a new analysis tool and the existing conversion code would not need to be altered The design of a multi agent system in JiVE must also take into account conversations that may never start The analysis of this aspect of a multi agent system 1s unforgiving If a conversation in the system is intended to be allowed to never execute then that must be explicitly defined To define this condition the initial state of the conversation should also be a final state In the absence of this the analysis checker will indicate a deadlock condition wherein the conversation in question never starts and the remaining conversations in the system are finished 3 2 4 Code Generation The code generation aspect of JiVE extends the ability of the user to design and test their conversations before writing code by generating the code needed to implement agents and conversations in JAFMAS JiVE generates Java source code files that match the JAFMAS format It allows the user to add custom agent code giving the agent it s behavior Even after the user adds custom code to the source code files the JAFMAS code generator can still regenerate the conversation code Appendix C gives an e
103. ti agent systems ZEUS specifies a design approach utilizing a three layer model of an agent the definition layer the organization layer and the co ordination layer It provides a set of graphical interfaces to allow a designer to create the multi agent system An agent is comprised of libraries that include communication using KQML social interaction multi agent coordination and planning and scheduling This tool generates source code for the agent based system in Java Nwana et al 1999 2 3 4 DECAF DECAF Distributed Environment Centered Agent Framework is a software toolkit for developing intelligent agents It provides user interfaces for the specification of the agent behavior including logical and temporal constructs It allows reuse of generic agent behaviors Its Plan Editor removes the designer of a multi agent system from the low level API and allows for the rapid development of agents which are generated in Java DECAF also provides some design time error checking and supports the use of agent communication languages Graham and Decker 1999 2 3 5 MASSYVE Kit The MASSYVE Multiagent Agile Manufacturing Scheduling Systems for Virtual Enterprise kit is a software kit for the development of multi agent systems It allows a user to configure modify and create a multi agent system it provides user interfaces to guide a designer through the process It also provides mechanisms to launch the agents both locally and remot
104. use Password Pe O the standard language cf Section 3 3 3 Project Name SupplyChain Figure 4 1 shows the login window Pressing Language Standard Okay will verify our User Name and Password eed Clear Exist Project When a user specifies a new project name the at a e project files and directory structure are created on the server When a user specifies an existing Figure 4 1 Login Window 39 project upon login the project files are loaded from the existing files and the client is initialized with the state of the project fe JAFMAS integrated Visual Environment Ji E Multi Agent System Design Window Proj BETES File Edit Edit Control Tools Help Ty subje ribute F ribute 41H 1m 1 0uUT Mm re 27 E T Agent Customer added ath by by System Agent Logistics added at 297 67 by System Agent Plant added at 296 212 by System Agent Customer s properties recieved Figure 4 2 Designing Agents The first window that appears upon successful login validation is the Multi Agent System Design Window Figure 4 2 This is where the agents are displayed and edited 4 3 Designing the Agents The Multi Agent System Design Window is where we add the agents and the agent s properties We start by adding the properties from which the agents will select These properties are the agent Type agent Attributes and Subjects To add an agent Type we select
105. vities the agent can engage in or resources it can produce For example in a supply chain a Plant agent may provide a Paint service or a Shipping service or both The Subjects that can be specified represent a subscription publication channel on which agents can send and receive multi cast messages to other agent s The process to add and remove Attributes and Subjects are similar A 4 2 2 Adding and Removing Messages When one of the pre defined agent communication languages is in use 1 e KQML or FIPA ACL the adding and removing of messages is disabled Otherwise messages are added to the design in a similar manner as the other properties however there is some additional information Message from the that can be specified for messages To add a message to the design select toolbar or Add Message from the Edit menu A window appears allowing the specification of the Message Type which is the unique identifier for the message This window also allows the specification of the message intent which provides additional information as to what the message is meant for in the system but does not differentiate the message in JIVE The mie ss je messages are removed by selecting the button on the toolbar or Remove Message A7 from the Edit menu The window that comes up will allow for the selection of a message to be removed A 4 2 3 Adding and Editing Agents Once prop
106. xample of the generated code The CodeGenerator is implemented as a static class which is invoked from the Repository class The CodeGenerator takes as parameters the entire database of objects in the system including agents conversations conversation rules messages as well as lists of all of the various properties The CodeGenerator systematically goes through each of those objects and places them in the correct section of code Any code that might be changed by JIVE when the code is regenerated is placed in between double brackets like in the following code example System defined fields Do not edit 28 public Conversation convl null AR Before the CodeGenerator regenerates the source code file it stores the user modified portion of the code i e the code not between the double brackets and sets it aside to be placed back in the source code in the same place In this way the user can manually modify the source code and still be able to regenerate the core agent and conversation code from JiVE assuming they don t edit inside the brackets 3 3 System Implementation This section provides a more detailed discussion of JiVE s implementation 3 3 1 Architecture The JiVE application is written in Java and uses a client server model The entire JIVE Package consists of a JIVE Server implemented as a Java application and a JIVE Client a Java Applet The server application is designed to run on a machine that has

JiVE: JAFMAS integrated Visual Environment

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