Session C1 1. Employing WS-BPEL Design Patterns for Grid Service Orchestration using a Standard WS-BPEL Engine and a Grid Middleware

focus on employing Grid technologies for information systems integration. The goal is to enable small and medium enterprises (SMEs) to integrate heterogeneous business information systems and to use external Grid resources and services with reasonable effort. To achieve this goal, we develop a Grid workflow middleware – the BIS-Grid engine – that is capable to orchestrate WSRF-based Grid Services. This engine is based upon service extensions to the UNICORE 6 Grid middleware, using an arbitrary WS-BPEL workflow engine. WS-BPEL is an XML format for workflow description and the industry de-facto standard language for service orchestration. One main design decision in BIS-Grid is to leave the WS-BPEL language unmodified to avoid incompatibility with commercial WS-BPEL engines, nor to modify a WS-BPEL engine to ensure its exchangeability and hereby the sustainability of the BIS-Grid engine [1]. Thus, our UNICORE 6 service extensions fill the gap between WS-BPEL and the Grid world. This is in contrast to other approaches where WS-BPEL for Grid Service orchestration is utilised. For example, in [2] a solution is presented that is based on extending BPEL4WS, the predecessor of the WS-BPEL language, also requiring extensions to the workflow engine. This leads to a proprietary solution in which the workflow engine is not exchangeable. Our design decisions led to several technical challenges. Some are solved by applying so-called WS-BPEL design patterns. One category of patterns is called Grid utilisation patterns, which describe how t