Workflow Modeling and Execution with Coloured Petri Nets in COSM

Modern distributed organisations use data communication increasingly fast, globally and at decreasing costs. Such developments facilitate flexible access to decentralized services in open networks and also allow coordination of complex interorganizational tasks as distributed applications. This paper describes concepts and recent extensions to the distributed systems architecture COSM (Common Open Service Market) which supports integrated design, implementation, and execution of both access to arbitrary services in open networks and concurrent workflow modeling. Formal basis of the workflow model are Coloured Petri Nets (CPN) which provide powerful means to specify and verify activity coordination in concurrent environments. CPN specifications, however, usually lack automated tool support for transforming them into efficiently executable applications. COSM, on the other hand, already provides a generic platform to manage distributed services (i.e. their properties, interfaces, etc.) in order to enable human users to engage easily in ad-hoc sessions with arbitrary service providers in open network environments. Extending COSM service descriptions with CPN workflow representations integrates dynamic workflow modeling into the system supported COSM service management platform. It could therefore help to bridge the gap between concrete system support for open distributed applications and formal models of concurrent workflow specifications. This paper presents both a brief review of COSM concepts and prototype implementation details of its first CPN extensions, motivated by a workflow example from a real-world project environment