A Practical Approach for a Workflow Management System

A variety of grid middlewares and workflow languages causes the existence of many workflow management systems (WfMS). Formalisms used to represent workflows vary from simple Directed Acyclic Graphs (DAG) to more complex (non deterministic) Petri Nets. Therefore aworkflowdescription is strictly bound to a particular WfMS and to the computational resources that WfMS address, as far as no cooperation among WfMSs exists. This might be critical in scientific workflows where a large amount of resources is usually needed. In this paper we propose a WfMS that aims at language independence and Grid middleware abstraction dealing with interoperability as proposed in the reference model of the Workflow Management Coalition (WfMC). The main goal of such WfMS is to provide an effective solution to run complex scientific workflows (legacy or not) taking full advantage of the distributed and etherogeneous nature of the Grid. APetri Net formalism has been chosen as internal representation due to its formal behavioral description and the existence of several analysis tools. Our proposed WfMS will be implemented on top of the gLite Grid middleware provided by the EGEE project because of its stability and large adoption.