一个基于自管理单元支持差分服务的Web容器

随着Internet的飞速发展,符合J2EE规范的Web容器已经成为部署企业Web应用的主流平台.同时,企业Web应用的多样化和复杂性的增长,迫切地要求Web容器提供差分服务的支持.然而,传统的Web容器采用尽力而为的服务模型,无法提供差分服务支持.已有的研究采用准入控制、优先级调度等方法来为Web容器提供差分服务支持,但是它们只能提供单调、静态的差分服务策略.提出了一个基于自管理单元的Web容器DSWC,它能够根据SLA定义提供两级差分服务支持.此外,提出了一个自适应差分服务策略选择算法,它能够根据动态变化的运行环境自适应地选择差分服务策略.原型系统的实验结果显示,DSWC能够有效地为请求提供符合SLA定义的细粒度的差分服务支持.

A Self-Management Unit-Based and Differentiated Service-Enable Web Container

Web container conforming to J2EE specification,which provides runtime environment for servlet and JSP and adopts best-effort service mode,has become an effective platform to deploy enterprise Web applications on Internet.However,complex business Web applications require Web container to provide differentiated services that traditional Web container does not provide for requests from different clients according to role or payment etc.Some approaches such as admission control and priority scheduling have been applied to provide differentiated services for Web container,but they do not consider differentiated services in finer granularity so that they can only provide monotone and static strategy of differentiated services.To improve the deficiencies of traditional Web container,the requirement of differentiated services is analyzed and a differentiated service Web container(DSWC) based on self-management unit(SMU) is brought forward.In DSWC,process modules are encapsulated into SMUs,which are connected to compose a SMU chain.DSWC provides SMU-based and SMU chain-based differentiated services for requests according to SLA(service level agreement).At the same time,an adaptive strategy selection algorithm is also presented,which can adaptively select different strategies of differentiated services based on the dynamic environment.The experiments of prototype show DSWC can effectively provide differentiated services according to SLA for different type of requests.