Design and Implementation of a Distributed Workflow Enactment Service
Esin Gokkoca, Mehmet Altinel, Ibrahim Cingil, E.Nesime Tatbul, Pinar Koksal,
Asuman Dogac
Software Research and Development Center
Dept. of Computer Engineering
Middle East Technical University (METU)
06531 Ankara Turkiye
asuman@srdc.metu.edu.tr
Abstract
Workflows are activities involving the coordinated exe-
cution of multiple tasks performed by different processing
entities, mostly in distributed heterogeneous environments
which are very common in enterprises of even moderate
complexity. In current commercial workflow systems, the
workflow scheduler is a single centralized component. A
distributed workflow enactment service on the other hand
should contain several schedulers on different nodes of a
network each executing parts of process instances. Such
an architecture would fit naturally to the distributed hetero-
geneous environments. Further advantages of distributed
enactment service are failure resiliency and increased per-
formance since a centralized scheduler is a potential bottle-
neck.
In this paper we present the design and implementation
of a distributed workflow enactment service based on the
work given in [12]. Yet by starting with a block structured
workflow specification language we avoid the very general
set of dependencies and their related problems. In this way
it is possible to present a simple algorithm for distributed
scheduling of process instances. Further benefits of the ap-
proach are the ease in testing and debugging the system and
execution efficiency through reduced number of messages.
1 Introduction
Workflows are activities involving the coordinated exe-
cution of multiple tasks performed by different processing
entities. Since they execute in distributed heterogeneous en-
This work is partially being supported by the Turkish State Planning
Organization, Project Number: AFP-03-12DPT.95K120500, by the Scien-
tific and Technical Research Council of Turkey, Project Number: EEEAG-
Yazilim5, by Motorola (USA) and