The JOURNEY active network model

Faster processors are quickly enabling a new class of computationally inten sive applications that actively transform information flows. Performing suc h computation at the terminal end is contrary to current trends toward low- power terminal devices, Moreover, scalability and efficiency concerns are a lso encouraging service providers to outsource computation when operating u nder loaded conditions, To address the problem of deploying such applicatio ns, we introduce the JOURNEY network model, which provides computation as a n integrated network service, Contrary to other distributed computing models, JOURNEY does not attempt to guarantee that a given computational job will indeed be completed. Instead , the JOURNEY model trades off such hard guarantees in favor of architectur al simplicity, and hence scalability, In order for the JOURNEY model to be applicable to real-time multimedia flows, we introduce the notion of soft q uality-of-service (QoS) that provides a probabilistic bound on the unproces sed packet rate (UPR), Based on this notion, we describe a packet-processin g admission control algorithm that additionally takes into consideration a flow's real-time constraints. We also propose a computing router architecture that is based on cluster te chnology, This architecture can track technology advances in both routing a nd computing independently. We further present a motivating multimedia appl ication that employs a semantically driven video transcoding service within the JOURNEY framework we implemented, and describe our experience along wi th performance measurements.