Design And Implementation Of Instant Messaging System Based On SIP Protocol

Instant Messaging, which has become an essential network application in our daily lives, provides people with the service of real-time communication. Currently, well-known business systems often use proprietary protocols, which causes many difficulties to the integration of IM service. It has been increasingly necessary to develop and establish an Instant Messaging system based on the open network architecture in the new network environment.This thesis proposes a SIP-based Instant Messaging System, which aims to provide an instant communication scheme using an open protocol and realizing the interoperability among multi platforms and service, and finally the corresponding realization has been completed. SIP is a signaling control protocol of application layer, which is used for session establishment, configuration and teardown. Meanwhile, due to its features of brevity, open and simplicity of expansion, SIP is particularly suitable for building Instant Messaging platform. With SIP becoming one of the core protocols in the NGN network, the interoperability of the open IM platform based on it will also be possible.The Instant Messaging System proposed by this thesis is designed and implemented upon the Multimedia Scheduling Server developed by the company where the author doing his practical training. It consists of a number of functional modules, including SIP channel module, IM module and Presence module. The SIP channel module is responsible for the processing of common SIP messages and media streams, while applying for a SIP channel to communicate with the PBX module in the server. The module mentioned above is the basis of this thesis’design and made up of several functions, such as message parsing, registration management, call management and media delivery. This thesis focuses on both of IM module and Presence module, with which used to render services of common Instant Messaging. IM module mainly handles the Instant Messaging service, which includes the sending, receiving and storage of the instant messages between users. Presence module is responsible for the processing of Presence service in the system, including the subscription, publication and notification of the presence information.First of all, this thesis explains why to choose SIP protocol as the basis of the development and then analyzes SIP protocol and the related ones. Afterwards it elaborates the design and implementation of the SIP-based Instant Messaging System which includes the SIP channel module, IM module and Presence module. Finally, the system functional testing is carried out. The result shows that the system is able to meet the basic demands of Instant Messaging and Presence service. Meanwhile, the system is available as a reference for industry product.