The Design And Implement Of Instant Messaging System Based On P2PSIP In Ophone

In this paper, we'll start from the web applications under the background of intelligent terminal to the development of the Instant Messaging System in the web-time. We also discribed two popular protocols--SIP&P2P and showed their characteristics and their fields.Then we analysised the demond of the systerm and designed the Ophone/Android Instant Messaging System on the base of P2PSIP. We separated the system to several levels including user interface, logical functional module and interface engine. After the test we found the system can login and download the list of friends, subscribe friends'status, send and receive messages and support the function of edit your friends. When the server is too heavy or the user send to the application, the systerm will switch to P2P model, use the Kad protocol to make the terminal to a Kad net. Then use the searching and storage function to realise the searching and storage of. The well design of logical function will realise the refering of instant message and status as well as the off-line message under the P2P protocol--this is because the distributed system can buffer memory the message and let the users know it when they are on line. By using the object serialization technology, the system also realised the off-line friends list and manage the system log by the function of worklog management of Android.