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Service Representation, Discovery, and Composition for EMarketplaces W-J van Heuvel, J. Yang, M. P. Papazoglou Univ. of Tilburg, INFOLAB, The Netherlands © Dr. Jian Yang
Contents o E-services and E-Marketplaces o Running Example and Issues o Service Representation and SDL o Capability Analysis o Service Composition o State of the Arts © Dr. Jian Yang
E-services definition o o o E-services E-business o E-commerce o o o © Dr. Jian Yang An e-service is a self-contained internet-application that - conducts a transaction - completes a task, or - solves a problem and posseses the ability to to engage other e-services to complete its task; and can be used by people, businesses; on a pay per use basis
E-services Applicationson. Tap/ E-services portal Marketplace Search Business Scenario: Internet Buying Register Select Offer Front end Buyer Back office Financials & Logistics & HR Seller Front end Buy Receive Business Scenario: Internet Selling Sell Transact ! ULTIMATELY Dynamic Brokering of Services © Dr. Jian Yang Cash-in Back office Financials & Logistics & HR
Vertical E-services Travel E-Service Restaurant reservation E-Service Business Model / Workflow Customer Knowledge Enterprise Product Knowledge Airline booking E-Service Value Chain Network Weather E-Service Reservation E-Service © Dr. Jian Yang Customer Information E-Service Hotel booking E-Service
features Dynamic Discovery: • can find any resource on the Internet based on its description Brokering: • provided the match in the background Composition: • individual services are automatically linked to meet the service request Mediation: • automatically notifies all associated services of changes/updates © Dr. Jian Yang
Process Integration for EC (PIEC) framework Tools and framework for automated service development o Service representation (SDL) o Service discovery o Service combination o Mapping e-services to objectified legacy systems o © Dr. Jian Yang
Running Example Assume that there are several car sell service available on the web, and the entire buying process requires the following four main e-services: o Search for a car and car dealer. o Negotiate about the terms of delivery o Order a car o Delivery and payment © Dr. Jian Yang
Issues o Service description ä The domain model used to describe “what’s about” ä The service capability (components) ä The access syntax o Service discovery ä Semantic relatedness ä Capability analysis ä Syntactic analysis © Dr. Jian Yang
The Service Description Language (SDL) Provides a comprehensive description of service semantics: Service properties: general info. , service access info. o Service ontology. o Service cost. o Payment method. o Actors. o Authorization/security/visibility. o Service contents. o Service capability. © Dr. Jian Yang o
Specification of a Request
Specification of the Car Seller © Dr. Jian Yang
" src="https://present5.com/presentation/b4daf78d6979af960fc690c1672a11da/image-13.jpg" alt="Specification of the Car Seller (continued) © Dr. Jian Yang
Service Model New_car_Sell Old_Car_Sell Search_Car Provide_Car_ Information © Dr. Jian Yang Negotiate Provide_Contact_ Information Order_Car Provide_Payment_ Information Fulfillment Provide_Shipment _ Information
Capability Analysis o Service capability derivation algorithm o Matching and partial matching algorithms to determine o Identical o Part-of o More restrictive o Overlapping o Not relevant © Dr. Jian Yang
Algorithm for Capability Derivation begin capability(s): ={s}; for each p in part(s); capability(s): =capability(s) p; endfor; for each q in super(s) capability(s): = capability(s) q; s: =q; for each p in part(s); capability(s): =capability(s) p; endfor; end; © Dr. Jian Yang
Matching Services begin Q: the set of request services; FC: Cost function; Found: =Null; Cost: =Max_cost; For each service s in the registry if capability(s) Q then C: =FC(s); if c
Service Composition Given an use interface description in SDL S 0 and a repository of several SDL-descriptions S 1…Sn, we want to know which SDL call interface(s) description in the repository fits best to the given SDL description Solution: translate an SDL description to a type-tree. © Dr. Jian Yang
© Dr. Jian Yang
State of Arts UDDI, WSDL, E-speak … Limitations? • State of the art service representation languages are not able to sufficiently capture the semantics of the business domain and the structure of the service (e. g. , the sub-services, the parts of the services); • Business process dynamics are only partially covered by current service descriptions in terms of operations (capabilities): business dynamics and policies (constraints) are lacking. Business protocols only have been treated in cursory manner thus far. • The e-service repository and query language have only been partially implemented. The current service searching is only based on attribute (or name) match. More research needs to be conducted to construct a more advanced repository and searching system. • Service descriptions are not based on a solid type system. This puts a severe barrier on composing e-services dynamically, as the conformance of the resulting e-service suite can not be checked at runtime. • E-service searching is only based on attribute match which is not sufficient enough to deal with partial matches and semantic conflicts. © Dr. Jian Yang
Conclusion o. A framework for service description o Algorithms for service capability analysis and matching o Techniques for describing service composition © Dr. Jian Yang