1 Stanislaw Ambroszkiewicz in cooperation with D. Mikulowski, T. Nowak, L. Rozwadowski, K. Miodek IPI PAN, Polish Academy of Sciences and Institute of Informatics, University of Podlasie Agent Based Infrastructure for Web Service integration Sopot June

2 Web services: an idea to be realized  Web services  Web services are self-contained, self - describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions that can be anything from simple requests to complicated business processes... Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service (in an automatic way!).  From service providers’ point of view, if they can setup a web site they can join global community. From a client's point of view, if you can click, you can access services.

3 Web service integration: the background zInternet (TCP/IP) -->> simple and ubiquitous computer networking zWWW (HTML /HTTP) -->> simple and ubiquitous access to data zWeb services (a magic protocol) -->> simple and ubiquitous access to applications API(applications) Web services (applications) for automatic service discovery, invocation, and composition a magic protocol

4 zWeb Services are applications located at the border between Cyberspace and the real (outside) world. They process data (e-documents) inside Cyberspace, and effect the outside world. Our approach: agent based service integration How to realize it? Cyberspace (TCP/IP) agent e-doc effect outside world

5 zTasks are generated by users’ / programmers API. zThey describe what is to be done in the outside world zA task must be translated into e-doc processing in the Cyberspace Our approach: agent based service integration How to realize it? Cyberspace (TCP/IP) agent e-doc effect outside world

6 zAgent is a process dedicated to a particular task realization. The task could be realized by a composition of some of the available services. zAgent determines what initial e-docs must be provided by the API. Our approach: agent based service integration How to realize it? Cyberspace (TCP/IP) agent e-doc effect outside world

7 zAgent coordinates data processing (e-documents flow) needed to realize the task. Nothing more!. Capabilities to perform actions, process data, and effect the outside world are in services! Our approach: agent based service integration How to realize it? Cyberspace (TCP/IP) agent e-doc effect outside world

8 zConclusion: A generic language for describing data processing controlled by agents in networked environment (Cyberspace) is needed! zLet’s design such language! Our approach: agent based service integration How to realize it? Cyberspace (TCP/IP) agent e-doc effect outside world

9 zresources - data (e-documents) collected in types, e.g., Typ1, Typ2,... zservices - applications where the resources are stored and processed: ytype of operation performed by the service: xprecondition form_in xpostcondition form_out zfunctions implemented by operations, e.g., f; parameter a is of type Typ1, the term f( a ) is of type Typ2 Language: What do we want to describe?

10 ztasks specify what is to be processed, how and when, and where the result is to be stored: ywhen - timeout: ( leq, gmt(), date ), i.e., the current GMT time is less or equal to date ywhere - relation: (is_in, res, ser ), i.e, a resource res is in service ser Language: What do we want to describe?

11 ztask example: y“resource res1 is processed by function f and the result is stored in service ser1 by the time date1” zformally: ( is_in, f( res1 ), ser1 ) and ( leq, gmt(), date1 ) Language: What do we want to describe?

12 zService attributes: yoperation_type( service ) is a pair of atomic formulas: form_in and form_out x ycommitments( service ) is a pair of atomic formulas : form_in and form_out Language: What do we want to describe?

13 zAgent is a process dedicated to a single task realization zAgent attributes: yintentions( agent ) is an atomic formula yknows( agent ) is an atomic formula ygoals( agent ) is an atomic formula ycommitments( agent ) is a pair of atomic formulas: form_in and form_out Language: What do we want to describe?

14 Agent architecture: the idea of universal format for agent state zConsequences of our language: ynew (?) agent architecture, yagent state(Soul) as a universal data format for storing essential data of agent process MIND: MIND: Procedure for workflow formation and management BODY: BODY: Action execution and perception Goals History Intentions KnowledgeCommitments SOUL: collections of Entish formulas perception action execution control

15 zTerms are constructed in the standard way zComposite formulas are constructed using only conjunction, disjunction and implication; no quantifiers and no negation! Language: Term and formula construction

16 Language Entish Don't ask what it means, but rather how it is used. - L. Wittgenstein zEntish is a simple communication language for protocol construction: ye.g., service invocation, composition supporting 2PC transactions zDescribes only static relations between agents, services, and resources: y no actions, fully declarative language z 0.5 order logic language: yno quantifiers, no negation zAbility to express agent / service mental attributes: yintentions, goals, commitments, and knowledge as atomic formulas.

17 Language Entish (cont.) Don't ask what it means, but rather how it is used. - L. Wittgenstein zThe idea of webizing language (TBL) is applied: ylanguage elements have unique names URI. yEntish can be used and developed in a distributed way: any user / programmer can introduce new definitions, and new primitive concepts to the language. zMeaning: ystandard Entish has its own formal semantics yformal meaning (ontology) of new primitive concepts is not obligatory; it may be provided by the one who introduces them, e.g., ebXML, RosettaNet.

18 Web services protocol stack: our proposal Communication Language: Entish Integration protocols: composition with 2PC transactions, etc., Universal message format and transport: e.g., SOAP Internet (TCP/IP) Applications: web services our contribution

19 Abstract architecture: an example zEntish is a communication language for construction of: ypublication, discovery, task delegation, invocation, composition with 2PC transactions, etc., protocols SecretaryServices API API Web services (applications) InfoServices BodyServices(agents) Entish publication discovery invocation task delegation

20 èProtocol = two finite automata èAutomaton  states  transitions between the states What is Entish protocol? an idea agentservice message 1 message 2 …… message 3 …

21 Six steps of service invocation: 1.agent sends to the service: “my intention is φ” φ --> intentions( agent ) 2.service responds: ”I commit to realize φ if ψ is satisfied” ψ --> form_in( commitments( service )) and form_out ( commitments( service )) --> φ 3.ψ is satisfied 4.operation is performed by the service 5.φ is satisfied 6.service sends confirmation to the agent Our idea of service integration: Service invocation protocol

22 zA TASK is created by a user/ programmer (API) and delegated to an agent. zThe TASK becomes the GOAL of the agent. zAgent’s GOAL becomes its first intention φ0 (with a timeout!) zService SER-0 agrees to realize φ0 if φ1 is satisfied (a commitment) zφ1 becomes the next agent’s intention zService SER-1 agrees to realize φ1 if φ2 is satisfied zφ2 becomes the next agent’s intention zService SER-2 agrees to realize φ2 if φ3 is satisfied z … and so on Our idea of service integration: Service composition protocol agent φ2 API user / programmer φ1 φ3 SER-0 SER-1 SER-2 TASK communication φ0

23 z… and so on zFinally, φN becomes the next agent’s intention. zAgent is able to satisfy the formula φN zWorkflow (collection of commitments) for realizing agent’s goal is constructed! zAny formula includes a timeout zThe timeouts synchronize the workflow execution zWorkflow execution: zWorkflow execution: domino effect yφN --> … --> φ3 --> φ2 --> φ1 --> φ0 = GOAL Our idea of service integration: Service composition protocol (cont.) agent φ2 SER-3 API user / programmer φ1 φ4 φ3 φN SER-N SER-0 SER-1 SER-2 TASK workflow φ0

24 Example in semi-formal language idea to be formalized zClient task: purchase air line ticket for a flight from Warsaw to Geneva. zDeparture: June 22, zTimeout for task realizing: June 1, zThe client is associated with a user interface called GUI-01.

25 A travel agent office: The service called "FirstClass”. A travel agent office can realize the task. Type of operation performed by FirstClass consists of: zprecondition (called also formInOperationType) necessary for invoking the service: ?order is in the input of FirstClass. Elements of type Order contain data of the following types: Person, CreditCard, AirLine, Destination, Departure, Price.

26 A travel agent office: Type of operation performed by FirstClass consists of: zpostcondition (formOutOperationType) describing the result of operation performed by the service: ?invoice = fun(?order) and ?invoice is sent to ?GUI

27 Task delegation The client task is formulated and delegated to the agent. task01 = is_delivered_to( ?invoice )="GUI-01" and destination( ?invoice )="Geneva" and departure( ?invoice )="June 22, 2002" and timeout("June 1, 2002") zThe meaning is that an invoice is delivered to GUI-01 by June 1, 2002.

28 Task delegation The client task is formulated and delegated to the agent. The task01 is delegated to the process called agent01. Agent01 is responsible for the task realization. The formula: task01 implies intentions ( agent01 ) is sent to an serviceRegistry. The meaning of the formula is that satisfaction of task01 is an intention of agent01.

29 Creating of a workflow Agent is looking for a service that can realize its task. zSuppose that a serviceRegistry replies that the service FirstClass can realize task01. zThen, the same formula task01 implies intentions ( agent01 ) is sent to the FirstClass. zSuppose that the service First Class commits to realize the task01, however under the following condition:

30 Creating of a workflow Agent is looking for a service that can realize its task. pre = is_delivered_to(?order)="FirstClass" and timeout("June 1, 2002") and ( ( price(?order)="300euro" and airline(?order)="Swissair" and destination(?order)="Geneva" and departure(?order)="June 22, 2002" ) or ( price(?order)="350euro" and airline(?order)="Lufthansa" and destination(?order)="Geneva" and departure(?order)="June 22, 2002" ) or ( price(?order)="280euro" and airline(?order)="LOT" and destination(?order)="Geneva" and departure(?order)="June 22, 2002" ) )

31 Creating of a workflow Agent is looking for a service that can realize its task. zThe meaning of precondition is that ?order is delivered to FirstClass by June 1, 2002, and attributes of the ?order can be chosen from the ones listed in this formula. zActually, this attribute listing represents the offers.

32 Creating of a workflow Agent is looking for a service that can realize its task. zThe service replies to agent01 with the info about the commitment, formally: ( formOutCommitment(FirstClass) implies task01 ) and (pre implies formInCommitment(FirstClass) zThe meaning is that FirstClass commits to realize the task01, however under the condition that precondition is realized first. zThe formula precondition becomes the next intention of agent01.

33 Creating of a workflow Agent is looking for a service that can realize its task. zOnly GUI-01 can realize this intention. zOnce GUI-01 commits to realize this intention, a workflow for realizing. zTask01 is already constructed.

34 Executing of a workflow zThe workflow is executed if GUI-01 sends an appropriate order to FirstClass and the FirstClass sends back an invoice. zIn order to finish the transaction, the final confirmation must be sent to FirstClass. zAll this is performed in the Cyberspace and consists in sending and processing data (e-docs). zOnce the final confirmation is received by FirstClass, the effect in the real world take place, i.e., an appropriate ticket is printed and delivered to the client.

35 Conclusion: what has been done zEntish is a simple agent communication language yEntish spec. is completed and published in Springer LNAI 2203 yongoing XML translation of Entish syntax zPrototype implementation: yFirst versions of the integration protocols are already specified and being tested zOngoing implementation of XML based Entish on SOAP zDetails on our web site: ywww.ipipan.waw.pl/mas/