Pros and cons of distributed workflow execution algorithms

Abstract

As an implementation of business processes workflows are inherently distributed. Consequently, there is a considerable amount both of commercial products and research prototypes that address distribution issues in workflow execution and workflow management systems (WfMS). However, most of these approaches provide only results focussed on the properties of a specific workflow model, workflow application, and/or WfMS implementation. An analysis of generic requirements on distributed workflow execution algorithms and their applicability, advantages, and disadvantages in different workflow scenarios is still missing but will be shown in this paper. A comprehensive requirements analysis on distributed workflow execution forms the basis of our discussion of distributed workflow execution. In contrast to existing work that primarily focuses on non-functional requirements, this paper explicitly considers issues that originate in the workflow model as well. Subsequently, four basic algorithms for distributed workflow execution are presented, namely remote access, workflow migration, workflow partitioning, and subworkflow distribution. Existing WfMS approaches use combinations and/or variants of these basic algorithms. The properties of these algorithms with respect to the aforementioned requirements are discussed in detail. As a primary result, subworkflow distribution proves to be a well-suited application-independent and thus generally applicable distributed execution model. Nevertheless, application-specific optimizations can be accomplished by other models. © Springer-Verlag Berlin Heidelberg 2005.