摘要
远程教学是目前教学改革的重要内容,而虚拟实验室填补了远程教学中教学实践方面的空白,对提高远程教学的质量具有重要的意义。但是,当前的虚拟实验平台普遍不能支持异构资源的集成,限制了异构资源的重用,增加了平台开发的难度,降低了平台开发的效率,并且多为演示性实验,限制了用户动手能力以及创新思维的发挥。Web服务技术的出现,为处理这类问题提供了很好的解决方案。
Web服务技术采用以XML为基础的、开放的标准协议规范,屏蔽了软件平台和编程语言的差异,实现了异构资源的互操作。本文结合Web服务技术,提出一种面向异构资源集成的虚拟实验平台模型。平台采用Java Applet技术实现,使用户可以通过浏览器随时随地进行访问；以JavaBean组件技术和Web服务技术开发功能组件,实现异构组件的交互,提高组件的可重用性；采用独立的服务注册中心存储组件的描述信息,使组件和平台实现分离,提高平台的可扩展性和灵活性；提出一种基于Web服务组合的实验运行调度机制,减少网络传输的数据量和实验运行的延迟,提高实验运行的效率。平台允许用户根据需要,自主搭建合理的实验流程,进行创新实验；并且为用户提供组件发布接口,用户可以利用自己熟悉的编程语言开发组件,平台会将其自动发布为Web服务,供用户使用。
本文主要对Web服务技术在虚拟实验平台中的应用进行详细的阐述,并给出运行实例。文章的最后对前一阶段的研究工作进行总结,并阐述平台进一步扩充与完善需要研究的内容。
At present, distance learning is an important part of teaching reform, and virtual laboratory fills the gaps in the distance teaching pratice. However, the current virtual laboratories generally can not support the integration of heterogeneous resources, limiting their reuse and increasing the difficulty of platform development and reducing the efficiency of platform development. Also most of the experiments are demonstrative, and this limits practical ability and innovative thinking of the user. In this condition, web services technology privides a good solution to deal with these problems.
Web services technology adopts XML-based and open standard protocols, shielding the software platform and programming language differences, to achieve interoperability of heterogeneous resources. And with web serivces technology, the paper proposes a virtual laboratory platform based on integration of heterogeneous resources. There are some important aspects of the platform. First, it employs the Java Applet technology, which makes users can access it anytime and anywhere. Then, all the components in the platform are developed with JavaBean and web services technology, so that the platform realizes the interaction of heterogeneous components and improves the reusability. Besides, the platform uses an independent service registry center to save the information of components, so that it can separate from the components and improve scalability and flexibility. In addition, in order to reduce the amount of data transmission and improve the efficiency of running experiments, it is presented that a scheduling mechanism based on web service composition to run experiments. What is more, users are allowed to set up experiment procedures by themselves to carry out innovative experiments. And the platform provides some interfaces for users to release components. So users can make use of their familiar programming language to develop components, and these components will be automatically deployed as web services, which users can use as same as web services provided by the platform.
The paper focuses on how to use web services technology in the virtual laboratory platform, and gives a running instance. Finally, the paper summarizes the research works, and elaborates how to make the platform better in the future.
引文
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