© 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

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-business

E-commerce

E-services

E-services definition

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E-services

RegisterSearch

Select

Buy Sell

Offer

Transact

!

SellerSeller

Receive Cash-inBack officeFinancials & Logistics & HR

Business Scenario:

Internet Selling Business Scenario:

Internet Selling

BuyerBuyer

Business Scenario:Internet Buying

Business Scenario:Internet Buying

Front endFront end

Marketplace

Back officeFinancials & Logistics & HR

ULTIMATELY

Dynamic Brokering of Services

Applications-Applications-

onTap/onTap/E-services E-services

portalportal

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Vertical E-servicesVertical E-services

CustomerKnowledgeCustomer

KnowledgeProduct

KnowledgeProduct

Knowledge

ValueChain

Network

ValueChain

Network

Business Model/ Workflow

Business Model/ Workflow

EnterpriseEnterprise

CustomerCustomerInformationInformationE-ServiceE-Service

Airline bookingAirline booking E-ServiceE-Service

TravelTravelE-ServiceE-Service

Hotel bookingHotel bookingE-ServiceE-Service

RestaurantRestaurantreservationreservationE-ServiceE-Service

ReservationReservationE-ServiceE-Service

WeatherWeatherE-ServiceE-Service

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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

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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

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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

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Issues

Service description The domain model used to describe

“what’s about” The service capability (components) The access syntax

Service discovery Semantic relatedness Capability analysis Syntactic analysis

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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.

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Specification of a Request

<!--*********** Specification of Request ********************* --><request> <from src="http://www.infolab.nl/jian /> <vocabulary name="second hand car dealer" /> <service name="sell car" /> <service name="search car" /> <service name="Negotiate", option="optional" /> <service name="order car" /> <service name="fulfillment" /> <result> $serviceInfo </result></request>

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Specification of the Car Seller<!-- ************Specification of the car seller ************* --><service name="Car Sell" from src="http://www.cardealer.nl /> <vocabulary name="car dealer" /> <vocabulary name="second hand car" /> <vocabulary name="new car" /> <vocabulary name="car sell" /> ... <address> <street /> <city /> <state /> <postcode /> <country /> </address> <contact> ... </contact> <transport> ... </transport> <transportSecurity> ... </transportSecurity>

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Specification of the Car Seller (continued)

<contents name="carInformation" > <attributes name="make" /> <attributes name="model" /> <attributes name="year" /> <attributes name="type" /> <attributes name="price" /> <attributes name="description /> </contents> <service name="new_car_sell"> <sub_type> car_sell </type> </service> <service name="second_hand_car_sell" <type> sub_service </type> </service> <service name="search_car"> <type> part_service </type> <option> <input> "make" </input> <output> "carInformation" </output> </option> <option> <input> "type" </input> <output> "carInformation" </output> </option> </service> <service name="Negotiate"> <type> part_service </type> ....... </service>

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Specification of the Car Seller

<service name="Order_car"> <type> part_service </type> <service name="provide_car_information"> <type> part_service </type> <input> "confirmation_of_purchasing" </input> <output> "carInformation" </output> </service> <service name="provide_contact_information"> <type> part_service </type> <input> "customer_contacts" </input> <output> null </output> </service> <service name="provide_payment_information"> <type> part_service </type> <input> "payment_information" </input> <output> "confirm/reject" </output> </service> <service name="provide_shipment_information"> <type> part_service </type> ... </service> <service name="Fulfillment"> <type> part_service </type> ... </service name></service>

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Service Model

Car_Sell

New_car_Sell Old_Car_Sell

Search_Car Negotiate Order_Car Fulfillment

Provide_Car_Information

Provide_Contact_Information

Provide_Payment_Information

Provide_Shipment_

Information

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Capability Analysis

Service capability derivation algorithm

Matching and partial matching algorithms

to determine Identical Part-of More restrictive Overlapping Not relevant

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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; endfor; end;

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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;end;

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Service Composition

Given an use interface description in SDL S0

and a repository of several SDL-descriptions S1…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.

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Callinterface

Useinterface

Useinterface

E-service1

E-service2

a1

a2

a1

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State of Arts

UDDI, WSDL, E-speak … Limitations?•State of the art service representation languages are not able tosufficiently 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 servicedescriptions in terms of operations (capabilities): business dynamics andpolicies (constraints) are lacking. Business protocols only have beentreated in cursory manner thus far.•The e-service repository and query language have only been partiallyimplemented. 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 putsa 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 notsufficient enough to deal with partial matches and semantic conflicts.

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Conclusion

A framework for service description Algorithms for service capability

analysis and matching Techniques for describing service

composition