Nowadays, Web services are emerging as a major technology for achieving automated interactions between distributed and heterogeneous applications (Benatallah, Sheng, & Dumas, 2003). Various technologies are behind this achievement including WSDL, UDDI, and SOAP1. (Curbera, Duftler, Khalaf et. al. 2002) These technologies aim at supporting the definition of services2, their advertisement, and their binding for triggering purposes. The advantages of Web services have already been demonstrated and highlight their capacity to be composed into high-level business process (Benatallah et al., 2003). Usually, composite services (CS) denote business processes and are meant to be offered to users who have needs to satisfy.
Key Terms in this Chapter
Virtual Enterprise (VE): A VE is temporarily network of independent businesses that decide to join their efforts until certain objectives are accomplished.
Mandatory-Composite Services (MCS) vs. Optional-Composite Services (OCS): A MCS illustrates the compulsory participation of all component services to the execution process, while an OCS does not necessarily require the participation of all component services.
Composite Service (CS): A CS consists of component services that are either primitive (i.e., Web services) or composite (i.e., several Web services)
Web Services (WS): A technology for achieving automated interactions between distributed and heterogeneous applications. A WS is an accessible application that can be automatically discovered and involved by other applications (and humans) over the WWW. A Web service is specified with a service chart diagram.
Web Service Level Agreement (WSLA): A quality of service parameters that need to be satisfied for the execution of a WS or CS, such as response time and waiting time.
Service Chart Diagram (SCD): A SCD leverages an UML state chart diagrams, putting the emphases on the context surrounding the execution of a Web service rather than only on the states that a Web service takes.
Software Agents (SA): An SA is a piece if software that acts autonomously to undertake tasks on user’s behalf. In this paper, two types of SA are deployed: one that acts on behalf of a Web service (a service-agent), and another one that manages outsourced Web services (manager-agent), where the latter one supervises the work of service-agents.
Proactive Composition (PC) vs. Reactive Compositions (RC): PC is an off-line process that gathers in advance available component services to form CSs. RC is the process of creating CSs’ that are pre-complied and ready to be launched upon user’s requests.