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Semantic Web Fred Automated Goal Resolution on the Semantic Web

Semantic Web Fred Automated Goal Resolution on the Semantic Web. Michael Stollberg 38th Hawaiian International Conference on System Science Hawaii Big Island, 04 January 2005. Motivation. Promises of the Semantic Web: semantically enhanced web content processing

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Semantic Web Fred Automated Goal Resolution on the Semantic Web

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  1. Semantic Web FredAutomated Goal Resolution on the Semantic Web Michael Stollberg 38th Hawaiian International Conference on System Science Hawaii Big Island, 04 January 2005

  2. Motivation • Promises of the Semantic Web: • semantically enhanced web content processing • turn Web into environment for distributed computation • automated collaboration of entities over the Internet • Identified Key Technologies: • Ontologies: semantic terminology definitions • Web Services: computational facilities accessible over Web • Agents: electronic representatives acting on behalf of owner • Facilitate Automated Collaboration on the Semantic Web => Questions: • What are the building blocks and their functional interplay? • How to determine appropriate collaboration partners and resources? • Which techniques allow efficient & high-quality collaboration support? Semantic Web FredHICSS-38

  3. SWF Objectives / Outline • Framework for Automated Collaboration • collaboration model • building blocks identification • system components • Building Blocks Specification • Freds (agents), Ontologies, Goals, Services, Mediators • structure, usage, and interplay • semantic resource description • Cooperation Establishment • dynamic cooperation establishment • approach & techniques for discovery and compatibility determination • components realization Semantic Web FredHICSS-38

  4. Collaboration Model A Buyer A Seller achieve a purchase cooperation / interaction needed to be achieved to be achieved needed for execution needed for execution Objective: “buy a chair” needs to be compatible Objective: “sell my product” needs to be interoperable Facility: Facility: product search, provide PO, receive payment, deliver product select product, accept PO, provide payment, receive product • every entity has objectives and facilities (symmetric partners) • cooperation only if profitable for each party Semantic Web FredHICSS-38

  5. Owner Owner Service Service Mapping to Technology: Building Blocks Fred B Fred A Domain Knowledge representative static Mediator OO Ontology representative static task delegation task delegation collaboration partners: compatible goals Goal Mediator GG Goal usable usable assignment / usage dynamic assignment / usage dynamic Mediator WG Mediator WG collaboration execution: interaction of interoperable services Mediator WW • ontology-based knowledge and semantic resource descriptions • dynamic goal assignment & service usage • collaboration if compatible goals & interoperable services • collaboration execution = service interaction Semantic Web FredHICSS-38

  6. System Components detects new created goals Goal Detector for each goal for each goal Service Discovery (GS Discoverer) detects potential cooperation partners discoverers possibly usable services Partner Discovery (GG Discoverer) for possible cooperations Cooperation Establishment determines service compatibility for possible service combinations Service Compatibility Determination (WW Discoverer) Cooperation Contract (F1 (G, {S}),F1 (G, {S}), …) Cooperation Execution execution facilities for service types & execution control / monitoring Cooperation Execution Environment (Meeting Room) monitors goal resolution status of participating Freds Goal Solver Semantic Web FredHICSS-38

  7. Social owner, preferences, policies, history electronic representative Fred dynamically assigned task service usage Goal task delegated to Fred for automated resolution Service provided services, usage permissions, used services resolved by Freds representative static assignment / usage dynamic • electronic representative of entities involved in service usage & provision • cooperative interface agent • not (pro / re) active: central system control Semantic Web FredHICSS-38

  8. Web Service Modeling Ontology WSMO – Top Level Notions SWF uses WSMO version 1.0 (www.wsmo.org) Objectives that a client may have when consulting a Web Service Provide the formally specified terminology of the information used by all other components Semantic description of Web Services: • Capability (functional) • Choreography (interaction) • Orchestration (composition) Connectors between components with mediation facilities for handling heterogeneities Semantic Web FredHICSS-38

  9. WSMO elements in SWF • Ontologies semantic terminology definitions used in all other element descriptions • Goals tasks delegated to Freds for automated resolution • Goal Templates and Goal Instances • main description notions: submission, postcondition, effect • Services computational facilities • SWF service types • description notions: non-functional properties, Capability, Choreography • Mediators connectors with mediation facilities for resolving heterogeneities • mediator types • source & target, mediation service Semantic Web FredHICSS-38

  10. Dynamic Collaboration Establishment Goal Detector Goal Instance GI GI GG Discoverer {GI} {S} GS Discoverer U {S} WW Discoverer boolean Cooperation Contract (F1 (G1, {S}1), F2 (G2, {S}2), …) Cooperation Execution Semantic Web FredHICSS-38

  11. Partner & Service Discovery • Action and Object Knowledge Distinction Action defines what is to be done; interacting entities need to have compatible actions • Action-Resource Ontology • Object defines whereon a action is to be performed; interacting entities need not-contradicting object definitions => Set Theoretic Object Matchmaking • set-based resource descriptions • matchmaking notions • realization in VAMPIRE (theorem prover) • Combination is needed (2 resources might have not contradicting objects but not-compatible actions) Semantic Web FredHICSS-38

  12. Components Architecture • Design Principles: • modular components (according to discovery facility) • layered architecture: • set-up time & runtime discovery • least expensive operations first • effective search space narrowing • GG Discoverer (Partner Discovery) • matches Goal Instances (active objectives assigned to Freds) • returns sets of Goal Instances (potential cooperation partners) • GS Discoverer (Service Discovery) • matches Goal Instance and Service Capabilities • returns set of Services (usable for cooperation execution by Goal Instance owner) Semantic Web FredHICSS-38

  13. Choreography and Service Compatibility Fred A (Partner 1) Fred B (Partner 2) Potential Coop. Partners (after GG & GS Discovery) Choreography Service Interaction Interface Service Interaction Interface • Choreography: • agreed & valid conversation protocol • Service Compatibility is a pre-requisite for valid conversation protocol: • all information to be exchanged are compatible • message exchange order allows deadlock-free & terminating interaction Semantic Web FredHICSS-38

  14. Service Compatibility with ASMs Choreography as Distribted ASM with Services and their interaction behavior models • Service Interaction Interface • as Sequential ASM: • States • State Signature • Guarded Transitions • Service Compatibility Determination: • Information Compatibility: • service descriptions use same / interoperable ontologies • message content is compatible (Object Matchmaking) • direction of messages is inverse / compatible • Communication Compatibility: • Choreography (i.e. composed global conversation protocol) is weak sound: • start and termination state, deadlock-free, terminating without additional input Semantic Web FredHICSS-38

  15. Aspects for Discussion • Collaboration: Agents and Semantic Web Services • Freds & Collaboration Model • WSMO • Goals and Services • Discovery Realization • Service Compatibility Determination Semantic Web FredHICSS-38

  16. SWF Goals Goal Template templates for desires to be delegated to Freds nonFunctionalProperties importOntologies usedMediators postConditions effects Goal Instance concrete desires (instantiated Goal Templates) assigned to a Fred for automated resolution instanceOf (goalTemplate) nonFunctionalProperties (WSMO-nfp + constraints on time, resources, goalResolution) owner (Fred) submission (instances) postConditions effects status (resolution status) instantiates refinement only • WSMO Goal • pre-defined • action-resource ontology • extended WSMO 1.0 Goal definition • Goal Instance Creation / Task Assignment to Freds • by user via SWF user interface • dynamically during cooperation establishment Semantic Web FredHICSS-38

  17. WS WS WS WSMO Web Service Description • complete item description • quality aspects • Web Service Management • Advertising of Web Service • Support for WS Discovery Capability functional description Non-functional Properties Core + WS-specific • Realization of WS by using • other Web Services • Functional • decomposition • WS • Composition Web Service Implementation (not of interest in Web Service Description) • Interaction Interface • for consuming WS • Messages • External Visible • Behavior • ‘Grounding’ Orchestration Choreography --- Interfaces --- Semantic Web FredHICSS-38

  18. SWF Service Model • SWF Service Types • Plans = internal service implemented in Java • Process = multiple-step / nested service • external Web Services (invoked via WSDL description) Services a computational resource available in the system, described as WSMO Web Services nonFunctionalProperties ofType nonFunctionalProperties importOntologies ofTypeSet ontology usedMediators ofTypeSet {ooMediator, wgMediator} capability ofType capability preconditions ofTypeSet axiom assumptions ofTypeSet axiom postconditions ofTypeSet axiom effects ofTypeSet axiom choreography ofType choreography • 1 common service description language • Orchestration not of interest Semantic Web FredHICSS-38

  19. Mediation • Heterogeneity … • Mismatches on structural / semantic / conceptual / level • Occur between different components that shall interoperate • Especially in distributed & open environments like the Internet • Concept of Mediation (Wiederhold, 94): • Mediators as components that resolve mismatches • Declarative Approach: • Semantic description of resources • ‘Intelligent’ mechanisms that resolve mismatches independent of content • Mediation cannot be fully automated (integration decision) • Levels of Mediation within Semantic Web Services (WSMF): • Data Level: mediate heterogeneous Data Sources • Protocol Level: mediate heterogeneous Communication Patterns • Process Level:mediate heterogeneous Business Processes Semantic Web FredHICSS-38

  20. WSMO Mediators Overview Semantic Web FredHICSS-38

  21. Mediator Structure Source Component WSMO Mediator uses a Mediation Service via 1 Target Component 1 .. n Source Component • as a Goal • directly • optionally incl. Mediation Mediation Services Semantic Web FredHICSS-38

  22. Action-Resource Ontology concept action compatibleAction ofType set action concept buy subConceptOf action compatibleAction ofType set sell concept sell subConceptOf action compatibleAction ofType set buy concept resource hasAction ofType set action concept goal subConceptOf resource concept service subConceptOf resource concept buyergoal subConceptOf goal hasAction ofType set buy concept sellerservice subConceptOf service hasAction ofType set sell Action Taxonomy Resource Taxonomy all resources are defined as instances of resource types Semantic Web FredHICSS-38

  23. Set-Based Resource Descriptions Information Space all possible instances of used ontologies Description Notion all possible instances that satisfy restricted information space • Goal Instance Postcondition • Objective: receive a purchase contract • for a wooden chair for Michael Stollberg, • payment with credit card • meta-varibale X (dynamically quantified • by matchmaking notion) • restrictions on several ontology notions • WSML syntax postcondition definedBy exists ?PurchaseItem(?PurchaseItem[ item hasValue ?PurchaseFurniture ] memberOf swfmo:product) and exists ?PurchaseFurniture(?PurchaseFurniture[ material hasValues {wood}, ] memberOf furn:chair) and ?X[ purchaseItem hasValue ?PurchaseItem, buyer hasValue kb:MichaelStollberg, purchasePayment hasValue kb:MSCreditCard ] memberOf swfmo:purchaseContract . Semantic Web FredHICSS-38

  24. X Set Theoretic Matchmaking Notions • Exact Match: RQ, RR, O, M ╞ x. (RQ<=> RR) • PlugIn Match: RQ, RR, O, M ╞ x. (RQ=> RR) • Subsumption Match: RQ, RR, O, M ╞ x. (RQ<= RR) • Intersection Match: RQ, RR, O, M ╞ x. (RQRR) • Non Match: RQ, RR, O, M ╞ ¬x. (RQRR) = RQ = RR Semantic Web FredHICSS-38

  25. Partner Discovery (GG Discoverer) Discovery Request initiating Goal Instance Discovery Result sets of compatible Goal Instances (2) GG Matcher GIg GIg GIi instanceOf, status = ‘open’ instanceOf Action-Resource Ontology (1) Cooperation Knowledge Filter GTi GTg Action Compatibility Semantic Web FredHICSS-38

  26. Discovery Request Goal Instance GIi (2) GIS Matcher Discovery Result usable Services Discovery Result (intermediary) instanceOf GTi (1) Pre-Selector Service Repository Service Filter Service Discovery(GS Discoverer) Action Equality Semantic Web FredHICSS-38

  27. Discovery Request set of services {S} Choreography Description Translator WSDL2StateSign BPEL2ASM (1) SCinfo Checker (2) SCcomm Checker yes no Discovery Result Boolean (service compatibility) under construction Service Compatibility Determination(WW Discoverer) Semantic Web FredHICSS-38

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