refers to a change applied in an ad-hoc manner to a workflow instance (e.g., by dynamically adding, deleting or moving activities). Usually, ad-hoc changes of a workflow instance become necessary to deal with exceptions or unplanned situations not anticipated at workflow design time.
Published in Chapter:
Flexibility for Distributed Workflows
Manfred Reichert (University of Ulm, Germany), Thomas Bauer (Daimler AG, Germany), and Peter Dadam (University of Ulm, Germany)
Copyright: © 2010
|Pages: 35
DOI: 10.4018/978-1-60566-669-3.ch006
Abstract
This chapter shows how flexibility can be realized for distributed workflows. The capability to dynamically adapt workflow instances during runtime (e.g., to add, delete or move activities) constitutes a fundamental challenge for any workflow management system (WfMS). While there has been significant research on ad-hoc workflow changes and on related correctness issues, there exists only little work on how to provide respective runtime flexibility in an enterprise-wide context as well. Here, scalability at the presence of high loads constitutes an essential requirement, often necessitating distributed (i.e., piecewise) control of a workflow instance by different workflow servers, which should be as independent from each other as possible. This chapter presents advanced concepts and techniques for enabling adhoc workflow changes in a distributed WfMS as well. Our focus is on minimizing the communication costs among workflow servers, while ensuring a correct execution behavior as well as correctness of ad-hoc workflow changes at any time.