【作者】 姜黎明；

【导师】 冯玉才；

【作者基本信息】 华中科技大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 Web服务平台为我们提供了非常成熟的高度异构分布式系统间跨平台、跨语言的互操作技术,但缺乏对安全、事务、可靠性消息传输等服务质量支持的缺点,阻碍了Web服务在企业级任务关键型系统中的广泛应用,对服务质量的支持是当前Web服务平台亟待解决的问题。通过动态发现和动态绑定服务质量元数据,以元数据驱动服务质量的保障是符合Web服务特点的解决方案。元数据驱动方式需要服务质量描述语言和服务质量保障的实现。在服务质量描述语言方面,经过详细对比,选择WS-Policy规范中的策略语言,并通过对安全和可靠性传输两方面服务质量需求的考虑,通过增加对安全方面服务质量的表达能力,扩展WS-Policy语言,将服务质量元数据表达成策略。通过将规范中策略操作符抽象成逻辑运算符,得出语言的数学模型,增加机器可读性,简化对服务质量元数据的解析工作。在保障实现方面,基于策略语言在开源消息引擎Axis2的基础上实现元数据驱动的服务质量保障框架的原型系统,提供带安全和可靠消息传输保障的Web服务调用。基于规范的实现,保证系统与其它Web服务平台的互操作性;基于扩展的设计,方便添加对其他服务质量的支持。通过指定控制消息,系统完整实现多策略协商的复杂交互模型。更多还原

【Abstract】 The Web service platform is gaining popularity as an highly mature approach of intergrating applications in diverse and heterogeneous distributed environments.One of the biggest barriers preventing widespread adoption of this technology in enterprise misson- critical applications is a lack of products that support non-functional features of web service,such as security,transactionality and reliability.The approach of using metadata-driven QoS enforcement through dynamic discovery and binding is a popular solution which comply with the features of web service.This solution needs a language describing QoS of web service and enforcements in concrete executing environment and mapping layer.Though detailed comparison and consideration on security and reliable messaging,the language to describe QoS requirement of a service in WS-Policy specification is extended to enhance the ablility of expressing security requirements.QoS requirements of web services are expressed as policies.A mathematical model is abstract from this language through the abstraction from policy operator to logic operator.This model make the language more machine-readable and thus greatly simplify the management and manipulation of the policy document.A medatada-driven web service QoS enforcement framework is designed and implemented based on the policy language and the Axis2 open source project.It provide web service invocations with secure and reliable messaging enforcement.It can interoperate with web services in other popular SOA platforms and can easily extended to provide support for other domain-specific quality requirements.Through specifying control SOAP message,the system completely support complex interoperation model of mutiple policy negotiation.更多还原