An Extension for SIP Instant Message Using Publish/Subscribe Mode

SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) is a protocol suite for instant messaging (IM) service, but it is inefficient in processing instant message in session mode due to its complex signaling processes and heavy header overheads, which makes it difficult to meet the QoE (quality of experience) requirement, especially in the usage scenario of mobile Internet and other traffic sensitive networks. This document describes an alternative Session Initiation Protocol (SIP) extension for instant messaging service. The extension uses the publish-subscribe mode to simplify signaling procedures and introduces message user agent (MUA) to publish and receive message, and message broker (MB) as an intermediary to exchange messages between MUAs. Message is tagged with a topic, and the lightweight message format is more suitable for traffic sensitive networks.