【作者】 路美娟；

【导师】 张悠慧；

【作者基本信息】 清华大学 ， 计算机科学与技术， 2008， 硕士

【摘要】 随着网络、硬件的发展和用户需求的增加,传统的“软件即产品”发布模式的弊端凸显,不能再满足更多的需求。而近年兴起的“软件即服务”模式以一种全新的方式诠释软件发布,克服了传统模式的种种弊端,现正在全球迅速普及,成为软件行业的发展热点。“软件即服务”模式即以服务的形式在网络上提供软件程序。国外已经出现了一些运作成功的提供软件服务的厂商。本文在“软件即服务”模式的基础上,提出了一种按需服务的软件系统,并对其中的文件系统虚拟化功能的关键技术进行了研究和实现。这种软件系统不仅没有了传统模式的缺点,而且可以实现了个人计算环境的移动性。用户无论身在何处,只要能上网,就可以随时获取软件服务,对用户本机只有兼容性的要求。本系统向客户提供一套客户程序包;客户运行客户程序登陆厂商服务器,获得软件服务。客户程序中包含文件系统过滤驱动和客户端应用程序,两者共同实现文件系统的虚拟化功能,即在客户机器上虚拟出一个实际存在于网络上的文件系统。文件系统过滤驱动过滤并截获客户对本机上的程序的访问,并将访问请求交给客户端应用程序;应用程序根据访问请求,调用P2P模块,从网络上的服务器和其他客户机器上获取数据,以此实现文件系统的虚拟。当客户访问服务器上的程序时,在客户看来就像在访问本机上的程序一样。在网络条件好、客户数量多的情况下,实现的效果会很好。本文通过实现客户软件包的两个部分(除P2P模块),较完整的实现了文件系统虚拟化功能。在实现过程中,针对驱动开发中具有代表性的问题给出了解决方案;在实验基础上,进行了功能/性能测试;并提出了一些设计上的优化方案,对未来的工作提出了建议。更多还原

【Abstract】 With the development of network and the increase of users’requirements, the shortcomings of the traditional software application delivery model,“Software as a Product”(SaaP), are emerging. A new model“Software as a Service”(SaaS) rises, in which software applications are provided as services over the Internet. The SaaS has become the industry preferred term and is gradually replacing the earlier models. There are already some successfully SaaS vendors abroad.In this article, we propose a play-on-demand SaaS system, and describe the implementation of the file system virtualization technolgies. This system overcomes the shortcomings of SaaP system. Also, the personal computer environment is highly portable when the customer carries personal data with him. As long as the customer can reach the Internet, she can access software service on demand wherever, only if the host system is compatible.In the system, the customers run a client application package to get software service. The client application package consists of a user-level application and a file system filter driver. Both of them implement file system virtualization through virtualizing a file system on the host which is actually on the Internet. The filter driver filters accesses to certain files on the host and hands them over to the application that will therefore call the P2P module to get data from the internet (server and other clients).This article presents the two parts above (except P2P) and implements file system virtualization. It gives solutions to general problems in driver development, designs the functional/performance test plan, proposes possible improvements and gives suggestions for future work.更多还原