Identifying a Minimum Sequence of High-Level Changes Between Workflows

Adaptive workflow management systems allow workflows to be changed in both the modeling and runtime stages, resulting in many workflow variants. Identifying a minimum sequence of high-level changes between two workflows represents a fundamental yet critical issue. The state-of-the-art approach utilizes digital logic to seek the optimal solution; however, this approach may face difficulties when advanced workflow patterns (e.g., loops) are involved, and it does not scale well. To address this problem, we first propose a naive approach that applies all valid changes to one workflow until the other workflow is found. Then, the approach is optimized from two aspects. First, we present advanced heuristics that significantly reduce the search space without pruning the optimal solution. Second, we employ the A
$^\ast$
search algorithm to direct the search procedure. Because the heuristic function used in the A
$^\ast$
algorithm is problem specific, we devise a consistent heuristic function to approximate the edit distance between two workflows, thereby accelerating the search. We implement our approach in a prototype tool and conduct extensive experiments on two data sets to evaluate its effectiveness and efficiency. The experimental results demonstrate that our approach outperforms the state of the art in terms of both application scope and scalability.