Modeling multimedia workflow patterns using Dynamic Petri Nets and Orc

In distributed multimedia presentation systems, a workflow is defined to specify which activities need to be executed and in which order. Workflows need to be modeled and verified for effective synchronisation during playout. To model several of these workflows, high-level petri nets have been commonly used. However, petri nets are not suitable for distributed applications and most of them are limited in their capability in modeling workflows having multiple instances with or without a priori runtime knowledge. In this paper, we address the modeling of complex workflow patterns and propose a new approach able to both represent complex distributed multimedia presentation using dynamic petri nets(DPNs) and to translate a verified set of specifications into the new deterministic programming language Orc. DPNs are programmable petri nets that can: efficiently model user interactions and synchronised iterative playouts, and ensure that they represent consistent presentations, while Orc allows providing easy implementations using a set of powerful constructs.