On the other hand, the form of distributed applications is changing with the rapid development of Internet. It moves from close, localized-oriented and static closely-coupled mode towards open, public and dynamic loosely-coupled mode. 随着Internet的出现和飞速发展,软件应用形态逐步从相对封闭、面向熟识用户群体和相对静态的紧耦合模式向开放、公共可访问和动态协作的松耦合模式转变。