Efficient SIP-Specific Event Notification

By Session Initiation Protocol (SIP), the entities in the network can subscribe to the resource or the call state for various resources or calls in the network. Those entities (or entities acting on their behalf) can send notifications when those states change. We propose a new approach to subscribe the information of part resources of the user’s resource list. Unlike existing approaches that either use reduplicate SIP messages to subscribe to these resources one by one, or use minimal SIP messages to subscribe to the entire resource lists to get unnecessary information, our approach uses minimal SIP messages to get necessary information of these resources. We implement it in Enhanced Resource List Server (ERLS) project and compare it with previous approaches by the performance evaluation. We systematically evaluated our approach under the same setting as previous ones. The system result demonstrated the power of our approach in reducing the CPU usage and the data size transferred: our approach only used one third as much CPU usage and data size transferred as the best previous approach at certain cases.