Contemporary business applications often employ a process layer in order to coordinate automated activities. One option to build such a layer is to use a workflow management system. But the all-or-nothing fashion of such systems makes them sometimes hard to integrate. In such cases, custom development is an alternative. Yet concepts for the micro-architecture of process layers in business applications are rare. We argue that the blackboard pattern, which is known to be suitable for knowledge intensive artificial intelligence applications, can provide an solid basis also for constructing process layers with workflow capabilities. This paper shows how the essential building parts of workflows are realized in a blackboard architecture. In this context, an in-depth discussion of important design and implementation tasks to be solved is given.