The software architecture of a distributed quality of session control layer

Collaborative multimedia systems demand overall session quality control beyond the level of quality of service (QoS) pertaining to individual streams in isolation of others. To this end, the authors have recently introduced the concept of quality of session (QoSess) control. At every instant in time, the quality of the session depends on the actual QoS offered by the system to each of the application streams, as well as on the relative priorities of these streams according to the application semantics. The authors present a framework for achieving QoSess control, and describe the architecture of a distributed QoSess control layer. In addition, they describe a new inter-stream bandwidth adaptation mechanism, which is used by the QoSess control layer to dynamically control the bandwidth shares of the streams belonging to a session