While in the traditional workflow processes the control flow is determined statically within process definitions, in declarative workflow processes the control flow is dynamic and implicit, determined by conditions that occur in the workflow data and the service environment. The environment consists of so-called active objects, which play a double role. On the one hand, they are persistent data structures that can be queried and managed according to the syntax and semantics of a query language. On the other hand, active objects possess active parts that are executable and represent workflow processes or tasks. The approach is motivated by features that are desirable in complex and less regular business processes: (1) the possibility of dynamic changes of process instances during their run, (2) mass parallelism of process instances and their components and (3) shifting the availability of resources that workflows deal with on the primary plan as a mean for triggering instances of proces...