【作者】 王晓航；

【导师】 牛纪桢；

【作者基本信息】 大连理工大学 ， 计算机应用技术， 2009， 硕士

【摘要】 Web服务组合作为基于Internet的典型的服务组合形式,正在得到广泛的关注。由于Web服务的松耦合特点,为保证多个服务交互获得正确的执行和一致性的结果,有必要为服务提供事务机制。目前,服务组合中的事务处理已成为一个研究热点。本文针对组合服务事务的长事务特点,提出了一个通用的支持事务机制的组合服务描述模型(UWSC-NTM),该模型的特点之处在于支持动态的基于事务的Web服务组合,并且具有丰富的执行语义,可支持复杂的Web服务组合。本文采用形式化的方法对该模型的执行语义进行验证,并提出了模型的良构性准则。基于该模型,设计并实现了一个组合服务事务恢复算法。该算法引入了事务执行器和事务协调器的概念,提出了基于候选服务队列的前向恢复方法和基于历史状态轨迹的后向恢复方法,不同于传统的集中式模型下的单协调器方式,采甩分布式的事务协调方法,解决了单协调器的性能瓶颈问题和单点失效问题,改善了组合服务的成功率和平均响应时间。本文又设计出一个基于资源划分的组合服务事务并发控制算法,该算法充分考虑了组合服务事务中的各种并发情况,引入资源单元、粗粒度划分和细粒度划分的概念来保证事务并发的高效性,通过测试验证了该算法对事务并发控制调度的语义可串行性。最后针对当前CICS事务管理器缺乏对组合服务事务的有力支持,设计了一个支持组合服务事务的原型系统,包含了事务管理器、并发控制模块、错误恢复模块。该系统在协调各成员服务的事务行为的同时,还提供了错误恢复和并发控制的功能。本文主要在组合服务事务模型、错误恢复、并发控制及支持事务的组合服务原型系统等方面进行研究,为组合服务事务的研究提供了新的思路和方法。更多还原

【Abstract】 Web service composition as a typical Internet-based service composition form, is widely attentioned. Due to the loosely coupled characteristic of web services, to ensure the proper interaction between each other web services and consistency of the results, it is necessary to provide the transaction mechanisms. At present, the transactional processing of composite web services has become a research hotspot.For the long running characteristic of web service transaction, this paper proposed a universal composition web services description model (UWSC-NTM) which supported the transactional mechanism. This model support dynamic transaction-based Web service composition, and has a wealth of execution semantics to support a complex Web service composition. In this paper, using the formal methods to verify the execution semantic of UWSC-NTM and proposed the well-formedness criteria. Based on the model, design and implement a composite service transaction recovery algorithm. The algorithm introduced the transaction executor and transaction coordinator concept, proposed CSQ based forward recovery algorithm and HST based backward recovery algorithm, different from the traditional centralized model of a single coordinator approach, using a distributed transaction coordinated approach to solve the single-coordinator of the performance bottleneck and single point failure problems and improve the success rate of the composite services and the average response time. This paper also designed a resource-division concurrency control algorithm for composite web services, which take full account of the composite service affairs of the various concurrent circumstances, introduce resource units, coarse-grained and fine-grained division concepts to ensure the transaction concurrency efficiency. This algorithm is verified by testing the transaction concurrency control semantic serializability. Finally according to the CICS transaction manager lack of composite web services transaction support, designed a prototype system includes a transaction manager, concurrency control module, error recovery module.In this paper, focus on the research of composite service transaction model, error recovery, concurrency control and prototype system for the composite web services, providing the new ideas and methods for this research area.更多还原