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Agent Model for Interaction with Semantic Web Services

Agent Model for Interaction with Semantic Web Services. Ivo Mihailovic. Overview. Introduction About Semantic Web About Web Services About Semantic Web Services The model of the agent eGovernment example. Introduction. An attempt to demystify the Semantic Web to the author

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Agent Model for Interaction with Semantic Web Services

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  1. Agent Model for Interaction with Semantic Web Services Ivo Mihailovic

  2. Overview • Introduction • About Semantic Web • About Web Services • About Semantic Web Services • The model of the agent • eGovernment example

  3. Introduction • An attempt to demystify the Semantic Web to the author • Agent for interaction with Semantic Web Services • Integration of eGov services: providing a single access point to all government services, the increase in their interoperability without affecting their autonomy, approach oriented towards citizens

  4. Semantic Web

  5. Web Services • The W3C defines a Web service as a software system designed to support interoperable Machine to Machine interaction over a network. • Require three basic components: A messaging service for communicating between resources on the Web (SOAP), An interface description language (WSDL), A registration service so that clients looking for a service can find them (UDDI).

  6. Semantic Web Services • Semantic Web Services are self-describing, semantically marked-up software resources that can be interacted with in a task driven automatic way. • Dynamic part of the semantic web.

  7. Semantic Web Services • Automated Web Service Discovery • Automated Web Service Invocation • Automated Web Service Composition • Automated Web Service Monitoring • Automated Web Service Verification • Automated Web Service Simulation

  8. Semantic Web Services • WSDL can specify the operations available through a web service and the structure of data • WSDL cannot specify semantic meaning of the data or semantic constraints on the data. • WSMO vs OWL-S

  9. WSMO

  10. WSMO • Ontologies – describe all relevant concepts and relations among them • Web Services - describe capabilities, interfaces and internal working of the Web service • Goals - describe the capability the user would like to have and the interface he would like to interact with • Mediators - define mappings between components

  11. OWL-S

  12. OWL-S Service Profile • Service Profile – describes what the service does, used for the discovery • Intended to be published in a WS registry • Classification through the creation of a subclass hierarchy (one WS can belong to multiple classes) • IOPEs represent Web service’s capabilities, they describe the service • Other features: contact information, category, quality rating etc.

  13. OWL-S Process Model • Process Model – describes how the service works, its operation, control and data flow • Used for selection, invocation, interoperation, composition, and monitoring of the WS • Process types: atomic, simple, composite

  14. OWL-S Grounding • Grounding specifies how to access the service in terms of communication protocols and message descriptions • Mapping from Process Model to WSDL

  15. Agent model • Example: The user wants to book a flight. • He should find a service that sells tickets, check if it accepts his credit card and book the flight • The agent can automate this using an ontology of Web services • Agent tries to resolve the semantics of the user with the semantics of the service • User provide goals, agent try to map them to actions

  16. Agent model • Example: Goal – to go on a business trip. Actions – to book a flight, a taxi to the hotel and a hotel room • Example: Goal – the change of address. • Agent needs two ontologies: • First to map user’s requests to available goals • Second to map goals to Web services

  17. Scenario of operation • Step 1) User enters the query • Step 2) Agent maps user’s requirements to goals • The hard part – needs NLP, needs to be able to interpret user’s constraints • Book me a flight if the weather’s nice.

  18. Scenario of operation • Step 3) Agent tries to discover a service for each goal • Step 4) If it cannot find an integrated service for a goal it tries to decompose it • Step 5) After making the plan of actions the agent invokes the services

  19. Area of application: e-Gov • Integration of services, increased interoperability, not affection the autonomy of government organizations • Government is a dynamic area, things constantly changing (especially in countries in transition) • Services easily changed, added or removed

  20. Area of application: e-Gov • E-Government Domain Ontology encodes organizational, legal, economic, business etc. concepts • Web services ontology should categorize services to enable discovery • Registry of Web services with the service descriptions • A change of the service requires the update of the description

  21. Service discovery • WSMO – comparing Goals to Web Service descriptions • OWL-S – using the Service Profile • Service classification by creating a hierarchy of subclasses of Service Profile • SWS yellow pages – a class-hierarchical taxonomy

  22. Service discovery • Classification by serviceProduct and serviceCategory properties • Mapping to an OWL specification of UNSPSC (United Nations Standard Products and Services Code) • Also can be connected to a classification outside of OWL

  23. Service composition • AI planning to form service composition • A planning problem P is a 3-tuple < I, G, A > • I – description of the initial state • G – description of the goal state • A – set of actions for state transformations • An action sequence (a plan) S is a solution to P if S can be executed from I and the resulting state of the world contains G.

  24. Service composition • States formed from user’s goals and services preconditions and results • Actions are descriptions of Web services which show how their execution modifies the state of the world • STRIPS algorithm

  25. E-Gov ontology • Needs to represent the viewpoint of citizens as well as government • Connecting terms from common language with their legal jargon counterparts • Descriptions of non web-based services as well • Planner could make hybrid composition

  26. Thank you!

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