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. The authors argue that the blackboard pattern, which is known to be suitable for knowledge intensive artificial intelligence applications, can provide a solid basis also for constructing process layers with workflow capabilities.