Design of a Petri Net-Based Workflow Engine

Several years of research are establishing Petri nets as a modeling formalism for scientific workflows; their formal semantics and the existence of several analysis tools, among others, make them suitable for complex concurrent processes' description. However, the non-determinism of the Petri Net model clashes with the imperative Turing- based environment provided by mainstream programming languages such as C/C++, Java and C#. Therefore several design decisions must be taken in order to provide a concrete implementation of a Petri Net-based engine. This paper proposes the architecture of a workflow engine - currently implemented in a workflow management system (WfMS) - with the goal to provide a reliable and efficient platform for the execution of scientific workflows in a grid environment. One of the design principle is the neutrality towards the underlying mechanisms for task execution, in order not to compromise interoperability with multiple infrastructures.