© Dr. Jian Yang Service Representation, Discovery, and Composition for E- Marketplaces W-J van Heuvel, J. Yang, M.P. Papazoglou Univ. of Tilburg, INFOLAB, The Netherlands

© Dr. Jian Yang Contents E-services and E-Marketplaces Running Example and Issues Service Representation and SDL Capability Analysis Service Composition State of the Arts

© Dr. Jian Yang o An e-service is a self-contained internet-application that - conducts a transaction - completes a task, or - solves a problem o and posseses the ability to to engage other e-services to complete its task; o and can be used by people, businesses; o on a pay per use basis o E-business o E-commerce o E-services E-services definition

© Dr. Jian Yang E-services RegisterSearch Select Buy Sell Offer Transact ! Seller Receive Cash-in Back office Financials & Logistics & HR Business Scenario: Internet Selling Buyer Business Scenario: Internet Buying Front end Marketplace Back office Financials & Logistics & HR ULTIMATELY Dynamic Brokering of Services Applications- onTap/ E-services portal

© Dr. Jian Yang Vertical E-services Customer Knowledge Customer Knowledge Product Knowledge Product Knowledge Value Chain Network Value Chain Network Business Model / Workflow Business Model / Workflow Enterprise CustomerInformationE-Service Airline booking E-Service E-Service TravelE-Service Hotel booking E-Service RestaurantreservationE-Service ReservationE-Service WeatherE-Service

© Dr. Jian Yang 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 Summary of e-service key features

© Dr. Jian Yang Process Integration for EC (PIEC) framework Tools and framework for automated service development Service representation (SDL) Service discovery Service combination Mapping e-services to objectified legacy systems

© 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: Search for a car and car dealer. Negotiate about the terms of delivery Order a car Delivery and payment

© Dr. Jian Yang Issues Service description The domain model used to describe whats about The service capability (components) The access syntax Service discovery Semantic relatedness Capability analysis Syntactic analysis

© Dr. Jian Yang The Service Description Language (SDL) Provides a comprehensive description of service semantics: Service properties: general info., service access info. Service ontology. Service cost. Payment method. Actors. Authorization/security/visibility. Service contents. Service capability.

© Dr. Jian Yang Specification of a Request $serviceInfo

© Dr. Jian Yang Specification of the Car Seller

© Dr. Jian Yang Specification of the Car Seller (continued) car_sell sub_service part_service "make" "carInformation" "type" "carInformation" part_service

© Dr. Jian Yang Specification of the Car Seller part_service "confirmation_of_purchasing" "carInformation" part_service "customer_contacts" null part_service "payment_information" "confirm/reject" part_service... part_service...

© Dr. Jian Yang Service Model Car_Sell New_car_SellOld_Car_Sell Search_Car Negotiate Order_Car Fulfillment Provide_Car_ Information Provide_Contact_ Information Provide_Payment_ Information Provide_Shipment _ Information

© Dr. Jian Yang Capability Analysis Service capability derivation algorithm Matching and partial matching algorithms to determine Identical Part-of More restrictive Overlapping 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<Cost then Found:=s; Cost:=C; end; end;

© Dr. Jian Yang Service Composition Given an use interface description in SDL S 0 and a repository of several SDL-descriptions S 1 …S n, 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

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 A framework for service description Algorithms for service capability analysis and matching Techniques for describing service composition