Efficient Querying and Resource Management Using Distributed Presence Information in Converged Networks

Next-generation converged networks shall deliver many innovative services over the standardized SIP-based IMS signaling infrastructure. Several such services exploit the joint presence information of a consumer, i.e. SIP entity requesting a service, and a vendor, i.e. SIP resource providing a service. Presence information is a collection of contextual attributes (e.g. location, availability, reputation), some of which change dynamically. Moreover, this collective presence information is distributed across multiple presence servers. While performing query matching based on joint presence information, a server usually routes each query to a locally available resource. However, skews in the spatio-temporal distribution of queries and resources may require queries to be routed to alternate servers with available resources. We propose a novel Resource-Aware Query Routing scheme, called RAQR, where each server proactively establishes gradients to suitable servers via a diffusion-based algorithm. Gradients are set up whenever a server anticipates scarcity of resources and withdrawn when the resource crunch is mitigated. We compare RAQR with alternative resource matching schemes and show that it adapts to spatio-temporal variations in resource availability, thereby leading to effective query matching with minimal control overhead.