Logic Based Look-Ahead for the Execution of Multi-perspective Declarative Processes

In declarative process models all the activities which do not violate a constraint of the process model can be executed. Consequently, the number of viable paths is large. In turn, when considering multiple perspectives during execution, i.e., constraints on resources and data values, it may happen that the execution of activities or the change of data values may result in the non-executability of crucial activities. Execution engines for single-perspective declarative process models have been extensively discussed in research where, among others look-ahead functionality has been investigated. Execution approaches for multi-perspective declarative models that involve constraints on data and resources, however, are less mature. In this paper, we introduce a logic based look-ahead approach for the execution of multi-perspective declarative processes. We use the look-ahead for simulating a fixed number of execution steps with regard to the existing trace and the choice of the next step. The look-ahead allows for estimating all consequences and effects of certain decisions at any time of process execution. We develop an algorithm for trace generation and checking traces using the logic language Alloy. We extensively evaluate our approach by means of a practical example and give some advice for further optimizations.