Notations for the Specification and Verification of Composite Web Services

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  2. Dr Simon Woodman
  3. Douglas Palmer
  4. Emeritus Professor Santosh Shrivastava
  5. Dr Stuart Wheater
Author(s)Woodman SJ, Palmer DJ, Shrivastava SK, Wheater SM
Publication type Report
Series TitleSchool of Computing Science Technical Report Series
Source Publication DateJune 2004
Report Number849
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Availability of a wide variety of Web services over the Internet offers opportunities of providing new value added 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. Furthermore, each individual service is likely to have its own sequencing constraints over its operations. It is highly desirable therefore to be able to validate that a given composite service is well formed: proving that it will not deadlock or livelock and that it respects the sequencing constraints of the constituent services. With this aim in mind, the paper proposes simple extensions to web service definition language (WSDL) enabling the order in which the exposed operations should be invoked to be specified. In addition, the paper proposes a composition language for defining the structure of a composite service. Both languages have an XML notation and a formal basis in the pi-calculus (a calculus for concurrent systems). The paper presents the main features of these languages, and shows how it is possible to validate a composite service by applying the pi-calculus reaction rules.
InstitutionSchool of Computing Science, University of Newcastle upon Tyne
Place PublishedNewcastle upon Tyne
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