An Approach to Engineer Communities of Web Services: Concepts, Architecture, Operation, and Deployment

Introduction

For the World Wide Web Consortium, a Web service ``is a software application identified by a URI, whose interfaces and binding are capable of being defined, described, and discovered by XML artifacts and supports direct interactions with other software applications using XML-based messages via Internet-based applications’’. For the last few years, the development pace of Web services has been spectacular (Benslimane, 2007,DPD; Daniel, 2005; Dustdar, 2005). On the one hand, several standards have been developed to deal with for example Web services definition, discovery, and security (Andrews, 2003; Curbera, 2002). On the other hand, several projects have been initiated such as Web services composition, personalization, and contextualization (Baresi, 2007; Medjahed, 2007). These standards and projects have usually a common concern: Web services composition. Composition addresses the situation of a user’s request that cannot be satisfied by any single, available Web service, whereas a composite Web service obtained by combining available Web services may be used.

Nowadays, competition between businesses does not stop at goods, services, or software products, but includes as well systems that offer the most recent and accurate information. For example, Google and Yahoo are both search engines. The common practice is to bind to one of the engines according to various factors like reliability, efficiency, previous experiences, financial charges, etc. Web services are definitely not excluded from this competition. Independent providers develop several Web services that could offer the same functionality such as currency exchange. It is reported in (Bui, 2005) that although Web services are heterogeneous, the functionalities these Web services offer are sufficiently well defined and homogeneous enough to allow for market competition to happen. To ease and improve the process of Web services discovery in an open environment like the Internet, we suggested in (Benslimane, 2007; Maamar, 2007; Subramanian, 2007) along with other researchers in (Benatallah, 2003; Medjahed, 2007; Medjahed, 2005) to gather similar Web services¹ into groups known as communities. The notion of group/community/cluster highlights the importance of developing guidelines that would permit the management of Web services to be now parts of communities. Although Web services are investigated in various research projects (Anderson, 2006; Foster, 2006; Mrissa, 2008; Younas, 2006) these guidelines still lack and hence, examining the following elements would be deemed appropriate: (1) how to initiate, set up, and specify a community, (2) how to specify and manage the Web services in a community, and (3) how to reconcile conflicts within a community and between communities?