基于状态方面的Web服务动态替换

Dynamic Substitution of Web Services through Stateful Aspect Extension

随着面向服务计算技术的成熟,服务复合已成为Internet上开发企业间业务协作的一种新模式,WS-BPEL是服务复合事实上的标准。但是由于复合服务所依赖的第三方伙伴服务的分布、自治和松散耦合等特性,在执行过程中易受到伙伴服务失效的影响,可靠性无法得到保证,因此需要支持在运行时对伙伴服务进行动态替换。目前的BPEL规范只提供有限的服务替换功能,当与伙伴服务的交互涉及到一系列有状态的会话操作时,服务替换就更加复杂。通过对面向方面的研究,提出面向BPEL语言的状态方面扩展。通过状态方面,记录与伙伴服务交互过程中的会话信息。在伙伴服务失效时,通过透明地替换伙伴服务,使得与当前伙伴服务的会话信息传播到功能等价的另一个伙伴服务上,以保证流程的正常执行。通过该方法,使得BPEL流程具有一定的自愈能力,增强了流程执行的可靠性。

As the service-oriented computing technology matures, service composition has became a new model for business cooperation among enterprises in internet era. WS-BPEL is the de-facto standard for service composition. However,because Web services are loosely coupled,distributed,and autonomous, the reliability of BPEL processes can＇t be assured when partner services fail. As a result, dynamic runtime substitution of partner services is needed. But BPEL provides only limited service substitution. And when the partner services are stateful, the problem gets more complex. This paper presented an stateful aspect extension of WS-BPEL. Stateful aspects were used to store the conversational details of partner services. In case of partner service failures, the conversational details can be replayed on another equivalent partner service transparently for the BPEL process. Our approach makes WS-BPEL have some ability of self-healing and improves the reliability of processes.