基于BPEL的容错Web服务组合的研究与实现

发布时间：2018-10-18 07:10

【摘要】：随着Web服务技术的不断发展，Web服务被广泛应用在军事、金融、电子商务等各个领域，Web服务的可靠性是决定这些业务系统能否成功运行的关键。与传统业务系统不同，Web服务通常被部署在不确定的网络环境中，Web服务的松耦合性使得Web服务的可靠性得不到保证。因此，如何提高Web服务的可靠性已经成为业界的研究热点。容错技术常用来提高软件的可靠性，容错的关键是程序多样性设计，网络中存在大量的Web服务冗余资源，因此，采用容错技术来提高组合Web服务可靠性是一个成本效益好的方法。文中提出只为系统中关键服务进行容错的思想，基于系统中服务之间的调用关系以及调用频率等信息提出了两个服务排序算法：WSRank1和WSRank2。算法WSRank1利用系统运行剖面对系统中的Web服务按照关键度进行排序；算法WSRank2不但利用了系统运行剖面信息，而且对系统中每个Web服务的可靠性进行了研究。接下来，对组合Web服务的容错策略进行了分析，提出了基于用户条件限制的最优容错策略选择算法，为系统中关键服务选取合适的容错策略。在对组合Web服务可靠性研究的基础之上，设计并实现了基于BPEL的组合Web服务容错规则。基于排序算法和BPEL容错规则，文中以银行业务系统为例，设计并实现了系统中的基本Web服务，通过BPEL对系统中基本Web服务进行了编配，，紧接着使用SoapUI对银行业务系统进行了可靠性测试。结果表明，银行业务系统的可靠性不能满足用户对系统可靠性的要求，因此需要采用容错技术提高系统整体可靠性。接下来通过大量的测试得到了系统的运行剖面，然后根据服务排序算法得出系统中的关键服务，并根据不同用户的限制对银行业务系统中的关键服务进行了容错。最后，本文对容错组合服务系统的可靠性进行了测试，并对可靠性结果进行了分析。实验结果表明，对银行业务系统中的关键服务进行容错可以大幅度提高系统整体的可靠性，这对组合服务在可靠性和开销之间的权衡起到了很好的指导作用。
[Abstract]:With the continuous development of Web services technology, Web services are widely used in military, financial, electronic commerce and other fields. The reliability of Web services is the key to the successful operation of these business systems. Unlike traditional business systems, Web services are usually deployed in uncertain network environments, and the loose coupling of Web services makes the reliability of Web services not guaranteed. Therefore, how to improve the reliability of Web services has become a hot spot in the industry. Fault-tolerant technology is often used to improve the reliability of software. The key of fault-tolerance is the diversity of program design. There are a lot of redundant resources of Web services in the network. It is a cost-effective method to improve the reliability of composite Web services by using fault-tolerant technology. In this paper, the idea of fault tolerance for key services in the system is proposed. Based on the information of calling relationship and frequency between services in the system, two sorting algorithms of services, WSRank1 and WSRank2., are proposed. The algorithm WSRank1 sorts the Web services in the system according to the criticality by using the system running profile, and the algorithm WSRank2 not only utilizes the system operation profile information, but also studies the reliability of each Web service in the system. Then, the fault-tolerant strategy of composition Web services is analyzed, and an optimal fault-tolerant policy selection algorithm based on user constraints is proposed to select the appropriate fault-tolerant strategy for critical services in the system. Based on the research on the reliability of composite Web services, the fault tolerant rule of composition Web services based on BPEL is designed and implemented. Based on sorting algorithm and BPEL fault-tolerant rule, the basic Web service in the system is designed and implemented by taking the bank business system as an example. The basic Web service in the system is programmed through BPEL. Then SoapUI is used to test the reliability of the banking system. The results show that the reliability of banking system can not meet the requirement of system reliability, so it is necessary to use fault-tolerant technology to improve the overall reliability of the system. Then the running profile of the system is obtained by a large number of tests, and then the critical services in the system are obtained according to the service sorting algorithm, and the critical services in the banking system are fault-tolerant according to the limitations of different users. Finally, the reliability of fault-tolerant composite service system is tested and the reliability results are analyzed. Experimental results show that fault tolerance for key services in banking systems can greatly improve the overall reliability of the system, which plays a good role in guiding the trade-off between reliability and overhead of composite services.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.09

【参考文献】