Declarative Workflows to Efficiently Manage Flexible and Advanced Business Processes

In this work, we present a new constraint-based workflow definition language called Saturn, which uses Linear-time Temporal Logic (LTL) to express workflow constraints. A declarative approach to model business processes has recently been advocated as a viable complement to, or even replacement of, more traditional imperative-style workflow definition languages. Such an approach offers multiple advantages especially in the context of so-called flexible business processes where the processes and the underlying workflow definitions tend to change over time.

One major innovation of the Saturn language is the way in which it deals with the task lifecycle. This concerns to what extent tasks are considered not as atomic entities, but as possibly overlapping processes that can be started, stopped or cancelled at a later time. Contrary to other approaches, the task lifecycle is fully incorporated in Saturn's semantics and must not be modelled explicitly in the workflow design. As a result, the power of the declarative formalism underlying the language is more fully exploited and we offer both an elegant and pragmatic solution to a known problem. Moreover, Saturn is extensible and allows to model the environment of the business process, i.e. the external elements that influence its execution. A preliminary experimental evaluation shows our implementation of Saturn to be competitive, and a first version of the system is currently being integrated in a commercial application under development.