Academic journal article Journal of Electronic Commerce Research

How to Track Composite Web Services? a Solution Based on the Concept of View

Academic journal article Journal of Electronic Commerce Research

How to Track Composite Web Services? a Solution Based on the Concept of View

Article excerpt

ABSTRACT

This paper presents an approach for tracking composite Web services based on the concept of view. Web services are subject to personalization when there is a need to accommodate user preferences. Preferences of users are of various types like when the execution of a Web service should be initiated and where the outcome of this execution should be delivered, too. To guarantee that user preferences are handled during the execution of Web services, a view offers the opportunity of zooming into the specification that composes these Web services. For the specification requirements, state chart and service chart diagrams are adopted. A deployed view over a progressing specification features the dynamic nature of tracking composite Web services.

Keywords: Composition, Context, View, Web Service.

1 Introduction

1.1 Motivation

Web services technology offers, nowadays, a major support for a new generation of information systems featured by different components that collaborate despite distribution and heterogeneity obstacles (Schahram and Schreiner, 2005; Chen and Meixell, 2003; Chen et al., 2003; Kwok and Chi, 2006). A Web service is a software component that other software components and humans can discover and trigger to satisfy different needs (e.g., weather forecasts). Several standards back the development of Web services for their discovery, description, and binding, respectively (Milanovic and Malek, 2004). Taking advantage of the extensible Markup Language (XML) in order to achieve their platform-independence feature, Web services also have the capacity to be composed into high level business-processes usually referred to as composite services. Composition primarily addresses the situation of a user request that cannot be satisfied by any available Web service, whereas a composite service obtained by integrating available Web services might be used (Berardi et al., 2003). Composing services rather than accessing a single service is essential and offers better benefits to users. For composition requirements, a composite service is associated with a specification that describes among others the list of component Web services that participate in the composite service, the execution order of the component Web services with respect to data and temporal dependencies, and the corrective strategies in case of exceptions. There exist multiple languages for the specification of Web services compositions including the Web Services Flow Language (WSFL) (Leymann, 2001) and the Business Process Execution Language (BPEL) (Curbera et al., 2003). The primary aim of these specification languages is to provide a high-level description of the composition process far away from any implementation concerns. The specification of composite services is also concerned with the semantics of information that the component Web services exchange (Sabou et al., 2003), but this is outside this paper's scope.

While much of the R&D on Web services have focused on low-level standards for publishing, discovering, and invoking Web services (Ma, 2005), it is deemed appropriate tracking the execution of Web services. However, very little has been achieved to date regarding this tracking due to several obstacles including: current Web services are not active components that can be embedded with context-awareness mechanisms, existing specification approaches for Web services composition typically facilitate choreography only while neglecting context and its impact on this choreography, and lack of guidelines supporting the operations of Web services tracking. One of the advantages of this tracking is the possibility of adjusting Web services according to user preferences and constraints over the environment (Maamar et al., 2005). Indeed, some users would like receiving answers to their personal requests directly submitted to their personal email instead of office email. Personalization is tightly related to the features of the environment in which the Web services are to be executed once they are triggered. …

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