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Distributed Enactment of Composite Web Services

Lookup NU author(s): Dr Simon Woodman, Douglas Palmer, Emeritus Professor Santosh Shrivastava, Dr Stuart Wheater



Availability of a wide variety of Web services over the Internet offers opportunities of providing new services built by composing them out of existing ones. Service composition poses a number of challenges. A composite service can be very complex in structure, containing many temporal and data-flow dependencies between their constituent services. However, constituent service operations must be scheduled to run respecting these dependencies, despite the possibility of intervening processor and network failures. The architecture must be scalable, providing a decentralised coordination of service execution rather than based on a centralised scheduler; this is particularly important for services spanning different organisations, where reliance on centralised coordination would be impractical. This paper presents the design and implementation of DECS: a workflow management system for Distributed Enactment of Composite Services. A novel feature of DECS is the separation between specification of service composition and its enactment. A DECS service specification can be deployed either for centralised or decentralised coordination, depending upon inter-organisational requirements. A prototype implementation of DECS has been performed using J2EE middleware. The paper describes the DECS task model for specifying service composition and the middleware services that have been implemented in J2EE for coordinating service execution.

Publication metadata

Author(s): Woodman SJ, Palmer DJ, Shrivastava SK, Wheater SM

Publication type: Report

Publication status: Published

Series Title: School of Computing Science Technical Report Series

Year: 2004

Pages: 16

Print publication date: 01/06/2004

Source Publication Date: June 2004

Report Number: 848

Institution: School of Computing Science, University of Newcastle upon Tyne

Place Published: Newcastle upon Tyne