Temporal Partial Order and Partial Reliability Service for Distributed Multimedia Applications

A Partial Order and partial reliable Connection (POC) is an end-to-end transport connection authorized to deliver objects in an order that can differ from the transmitted one. The service that this connection provides is also authorized to lose a number of objects. The POC approach establishes a conceptual link between both connectionless best-effort (CL) and connection oriented (OC) protocols. This approach is motivated by the fact that heterogeneous CL networks such as Internet are plagued by unordered delivery of packets and losses, which tax the performances of current protocols. Moreover, it has been showed, in several research works, that out of order delivery is able to alleviate the use of network resources such as memory and bandwidth, and reduces end-to-end transit delay. But, in order to take advantage of these benefits, applications must be able to relax some transport constraints. In this paper a temporal extension of POC, called TPOC (for Temporal POC), is introduced. TPOC offer a conceptual framework, which allow the QoS of distributed multimedia applications to be fully taken into account. The architecture for offering a TPOC transport service is introduced and evaluated for the transport of MPEG video streams. We demonstrate that POC connections fill not only the conceptual gap between CL protocols (such as UDP) and OC protocols (such as TCP) but also provides real performances improvements for the transport of multimedia streams such as MPEG video.