IM System Research And Implementation Base On SIP And MSRP

With the development of IP network, IM software has been an important part of modern people's life. The page-mode messaging has been one of the most important technologies in IM transport. Page-mode messaging is enabled in SIP via SIP MESSAGE method. The greatest problem of this method is that any one of the SIP proxy server maybe change the transport protocol from TCP to UDP or SCTP. UDP has no block controlling mechanism so that the proxy server will could not process the SIP requests because of the blocking. It will disease the bytes of the message.Using MSRP as the media layer protocol is a great method. It has a number of benefits over page-mode messaging. MSRP is a simple text-based protocol and runs over a protocol which supports blocking control. So the MSRP instant message will not meet blocking when in transport and the bytes of message will not be diseased. MSRP will not go through the SIP proxy server, thus cutting the burden of proxy server. Besides that, MSRP relay mechanism supplies a great method for the NAT problem.In this paper, actuality and problem of the IM development are analyzed firstly. Then, the session-mode messaging and its advantages are introduced. The characters of MSRP are analyzed. That makes the reader understanding about the MSRP.The key points of this paper are design and implementation of the IM system. In design part, the whole design is shown firstly. Next are analyzing about MSRP protocol stack, system requests flows, SIP application server and MSRP application server, as these parts are writer's main jobs in design step. In implementation part, writer's main job is developing MSRP stack and MSRP application server. So these two parts are introduced, including the design and the important files. After that, the test process is introduced and the result shows that the system works well in lab.At last, the NAT problem in MSRP transport is studied and writer design the result plan through the relay mechanism of MSRP. This design is tested to work well to face the NAT problem in MSRP.