| Nowadays, a large number of companies are running Microsoft Office Communications Server2007system in their IT environment. Using the Session Initialization Protocol (SIP), the OCS2007system provides a VOIP solution based on IP network including Instant Messaging, Web Conferencing, Audio/video/telephony conferencing and etc. The built-in instant messaging feature is easy to use, but lacks of the administration over the content of messages. This has become a pressing issue that needs to be solved.The thesis starts with the concepts, architecture and classification of information filtering technology. By comparing the different types of existing technologies, the filtering model applicable for instant messaging is determined. This is followed by an introduction of the SIP protocol which is the core of instant messaging. After that, the architecture of Microsoft Office Communications Server is explained in detail.A great emphasis of this thesis is put on the introduction of DFSA algorithm, which is short for Deterministic Finite State Automation, as well as the introduction of a brand-new instant messaging filtering system for Microsoft Office Communications Server which supports good performance, high accuracy and security, matching for both English and Chinese strings, and distinctive policies. The filtering system is detailed in aspects including design goal, work flow, overall framework, module design and code implementation.The thesis aims to make a significant breakthrough in the following aspects:1. Explore the content filtering in instant messaging2. Extend the functionality of Microsoft Office Communications Server to make it capable of filtering incoming messages.3. Optimize the existing algorithm and design a powerful filtering system.The tests showed that malicious instant messages can be filtered out by the system as much as possible. The system is able to assist businesses with strengthening the administration in instant messaging. |
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