Sip-based Mobile Office Key Technology Research

Office Automation was put forward on 80's last century in china. the concept of Office Automation has been widely accepted after several years development. Office Automation has been changed to information system which is centered as workflow from MIS system which centered as data interchange. As the dramatic development of science and technology , especially as the development of the computer technology, internet communication technology and information security technology, Office Automation has been developed to a higher level in technology as well as its application. Workflow technology has become more and more mature , and mobile multi-media system without limited of time and space has become a new bright point.This thesis is focus on the critical technology of mobile Office . Office Automation realizes its mobility through introducing SIP (section initialization protocol) which is a group of protocol used for digging out or locating client and building or modifying multi-media session. As the foundation of the modern VoIP system, SIP which is famous for its flexibility of connecting, call control function, route function and certification function is one of the critical protocols of soft switch.At the beginning, the critical technology of SIP protocol including function introduction, network entity, SIP header, SIP message and security mechanism of SIP is analyzed and studied, and three means of message transmission of SIP is analyzed in details. After that, JAIN SIP developing framework which is used for communication implement by SUN company is discussed in details according the comparison of several main open SIP implement source protocol stacks. Then centering on JAIN SIP, the basic methods of communication entity in SIP communication implement are described with Java language.SIP is the key technology in network communication. some specification and draft defined SIP in every aspect, but did not standardize in reality level. This causes some difficulty in application commonality and interoperate. Fortunately, based on Java language, JAIN SIP which put forward the modularization framework and a serial of standard interfaces solves this problem in some degree. This thesis implement the server and client function with the help of J2SE and J2ME. In the design of the server , we adopt the object oriented idea, and introduce the domain register to design the server. The splitting of stream among the servers is through domain. Proxy server only take charge of their own domains and implement the route function but for other domains they just process the transmitting job. This method compensates the disadvantage that Sip terminal can not be used after the IP address has been changed and largely improves the performance of the server.