Study On The Enterprise Instant Messaging System Based On SIP

With the development of network technology, Instant Messaging (IM) has been a requirement of on-line activities. And now the research hotspots in the Instant Messaging field have changed from Personal Instant Messaging (PIM) to Enterprise Instant Messaging (EIM).There are many mufti-media real time communication software on Internet at present. Major of them can realize communicate with others by text, audio and video. But the following questions generally exist in these software. First of all, they can not communicate with each other because they adopt themselves protocol. Secondly, lots of IM are difficult to adapt to the complicated network environment.This article analyses the above two problems carefully, adopt Session Initiation protocol to resolve the first problem, and design a solution to resolve the problem of NAT-Travel.SIP is an application-layer control (signaling) protocol proposed by IETF for creating, modifying and terminating sessions. It is designed as part of the overall Internet multimedia data and control architecture. However, the operation and functionality of SIP does not depend on any other protocols. In the thesis, the objective is to propose an SIP-based experimental system modal of real time multimedia that is easy to be integrated with other application software.First, the paper analyzing the problem of EIM.Then described the architecture, functions and call process of SIP in details, then showing the supervisory of SIP , and chactenstics and principle of RTP/RTCP protocols that are used to transmit real time multimedia data in briefly the contents;confirming the system designing object , offering the system logic model, analyzing the structure of system logic modules, and providing the design of each logic module;according to the logic module in the paper, the design complete the EIM based on SIP and analyzing the mostly key technologies adopted in the processing of completing the system in detail.At last, analyzes the security threats faced with by SIP and the actuality of SIP security mechanism.,and implement SIP security mechanism based on SIP.