“…Nowadays, more and more people work in distributed environments which characterized by spatial distribution, time synchronous or asynchronous, heterogene *Address correspondence to this author at the School of Computer & Information Science, Southwest University, Chongqing, 400715, P. R. China; Tel: +86-023-68252352(office), +86-13647690009 (Mobile); Fax: +86-023-68252051; E-mail: fly_fox2005@163.com ous environment, and supported by information technology. In this environment, human and information system can share data, information and knowledge, collaborate with other people and information system to complete some specific tasks [2,3]. At present, great deal of researches have been done in distributed environment, process and methods.…”