Workflows are activities involving the coordinated execution 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 heterogeneous environments. Further advantages of distributed enactment service are failure resiliency and increased performance since a centralized scheduler is a potential bottleneck.