Abstract
Service composition on the Grid is a challenging task as documented in existing research work. Even though there are initial attempts to use the Business Process Execution Language (BPEL) to compose services on the Grid, still there is a significant lack of flexibility and reusability needed in scientific applications. In this paper we present BPEL for Semantic Web Services (BPEL4SWS) – a language that facilitates the orchestration of Grid Services exposed as traditional Web Services or Semantic Web Services using a process-based approach. It is based on the idea of WSDL-less BPEL and incorporates semantic descriptions of process activity implementations which increases the flexibility of business workflows as well as scientific workflows. Following an approach that uses a set of composable standards and specifications, BPEL4SWS is independent of any Semantic Web Service framework and therefore can also utilize any kind of Semantic Grid services. The advantages of BPEL4SWS are: (1) compliance with standards, (2) independence on service technologies, (3) applicability for both business applications as well as scientific workflows that use Grid services, (4) improved flexibility of processes.