Logical channels: using web services for cross-organizational workflow

Universal cross-organizational workflow is one of the motivating goals behind the web services standards development efforts. Alternative flow languages, which allow web services to be combined and executed across organizations, have been created. Yet the mechanisms for true coordination between trading partners with workflow haven't been explored. We present three typical business scenarios involving multiple organizations in a workflow, and develop sequence diagrams of how cross-organizational workflow will unfold. In the process of doing this we identify logical channels of interaction that are distinct from the initial invocation of the flow – these include a connection between workflow engines in different organizations, as well as connections between monitor subsystems. We discuss the potential use of agents, and revisit the meaning of an interpersonal channel in a highly automated environment. After summarizing our model of logical channels, we look at how they might be realized physically, and conclude with general observations about the challenges of using web services for cross-organizational workflow.