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Volume 5 Issue 2 Special Issue: ECEG 2007 Den Haag
Evaluating Web Service Composition Methods: the Need for Including Multi-Actor Elements
Ralph W.Feenstra, Marijn Janssen, and René.W. Wagenaar
Faculty of Technology, Delft University of Technology, The Netherlands
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In a service-oriented architecture (SOA), an application is constructed from well-defined and readily available components, which are often accessible as web services. From an organizational perspective, such a situation consists of service providers and service requesters. Governmental organizations and departments can act as service providers by providing access to their information or functionality, and as service requesters by invoking services. The basic promise of SOA is that, by reusing components, development and maintenance costs can be lowered and flexibility is created. As such, more and more governmental organizations start collaboration with each other by creating web service compositions.
Although several composition approaches can be found in literature, the composition process is not well-supported. In this paper we present a novel composition evaluation approach based on human participation in workshops, and pair-wise comparison of methods. In these workshops the participants are asked to take on different roles and create compositions based on a set of web services. At the start of the workshop, participants are asked to fill in a survey containing the main hurdles, and at the end of the workshop the participants are asked to indicate to what extent the hurdles are solved by the method used.
The composition approaches found in literature do not take into account the e-government specific requirements. Current composition evaluating methods focus on the service usage phase and assume that all web service are well-described using standardized interfaces, are scalable, and have similar kind of performance and quality. This is an assumption that does not hold in practice, as interfaces and functionality are often slightly different, which requires adaptation before services can be reused. Moreover, social factors like trust in web service and service provider, different objectives and the not-invented here syndrome might block cooperation. Further research is aimed at extending the comparison of composition approaches.
Keywords: web service, web service composition, evaluation, workshop, multi-actor networks.
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