Automatic Orc Code Generation for Complex Workflow Patterns
Susan Elias, Palaniappan V., Lisa Mathew, K. S. Easwarakumar, Richard ChbeirAbstract: Multimedia services deal with the synchronized presentations of media objects located in distributed content servers. These presentations should be capable of handling iterations and user interactions efficiently. The workflow patterns of the presentations need to be modeled and verified for correctness prior to their creation/implementation. The new deterministic programming language model Orc can been used to specify workflows for distributed systems effectively. The powerful programming constructs in Orc lend themselves easily to implementations but the limitations in using Orc are i) verification in Orc has to be done explicitly and ii) programming skills are required to create the Orc code directly. We propose an approach where we could automatically translate a verified set of specifications into Orc code. High-level petri nets have been used to model and verify several of these workflows, however most of the existing petri nets are limited in their capability in modeling workflows having multiple instances with or without a priori runtime knowledge, as well as cancellations and implicit termination patterns. We propose the use of the new Dynamic Petri Net (DPN) to model and verify the presentations initially. The power of programming built into the DPNs make them well suited for modeling distributed multimedia systems. Petri nets can be modeled easily using graphical tools that capture their specifications at the backend. We present an algorithm that could automatically generate Orc code given the DPN specification of the workflow that represents the required multimedia presentation.
Keywords:
Dynamic petri nets, Orc, Distributed programming model, Multimedia presentations, Workflow patterns, Code Generations
doi:10.5019/j.ijcir.2004.170
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