BPEL Workflows Combining Standard OGC Web Services and Grid-enabled

When designing a Grid workflow, it might be necessary to integrate different kinds of services. In an ideal scenario all services are Grid-enabled. But real workflows often con-sist of Grid-enabled and non Grid-enabled services. One reason is that Grid-enabling services can be costly. Therefore it is favorable to solely Grid-enable the compute-intensive and time-consuming applications. Additionally, workflows should be allowed to include Grid jobs that exe-cute legacy applications. Another reason is that very often, third parties charge fees for accessing their services. Hence, it is impossible to convert such a third party service into a service that can be integrated into a Grid environment at all. This paper discusses problems of designing a workflow that consists of all these different kinds of services. The geospatial domain is exemplarily used to demonstrate diffi-culties that workflow designer have to overcome, i.e. con-structing a geospatial workflow by using combinations of conventional Web services (XML-based), standard OGC Web services and Grid-enabled OGC Web services (WSRF-based). The concept of a workflow engine capable of enacting these workflows is presented and an implementation based on the ActiveBPEL engine is proposed. 1