摘要： 随着Web 服务在电子商务等应用领域的快速发展，Web 服务中的QoS 管理，特别是Web 服务事务中的QoS 管理，成了一个迫切需要解决的问题，它对于服务的提供商和用户都同样重要。但是Web 的动态性、不可预见性等特点使得提供全面的QoS 管理成为一个富有挑战性的工作。并且，现有的Web 事务管理沿用了数据库的事务管理模式，不能提供深入全面的支持。为了加强QoS 管理，该文提出了基于QoS 管理的事务计算模型和基于QoS 的主动两阶段提交协议QA-2PC。QA-2PC 即使在操作系统和网络不能提供完全保障的前提下，也可以保证全面的质量服务。

关键词: 服务质量；Web 服务；事务；提交协议

Abstract: With the rapid development of Web services as a business solution to e-business, the quality of service (QoS) offered by Web services has become the top concern for service provider and their partners. Due to the dynamic and unpredictable nature of the Web, providing the acceptable QoS is really a challenging task. Web services transaction serves as the basis to achieve a general QoS support for e-business. However, current Web services transaction environments mostly inherit that of the database transaction, offering no comprehensive QoS support. To enhance QoS management, a transactional QoS computation model and QoS-based active pre-commit protocol (QA-2PC) are proposed. QA-2PC can effectively provide overall QoS guaranteed services even in the absence of operating system and network QoS support.

Key words: Quality of service; Web services; Transactions; Commitment protocol