Abstract: Internetware is a new software paradigm that facilitates the construction of collaborative applications over Internet， in which applications can be built by composing existing web services. Transaction processing is a key mechanism to make the internetware applications reliable. Due to the autonomy of individual web service and the long-running nature of internetware applications， the strict isolation property among transactions must be relaxed. Thus it becomes a vital problem to ensure the correct concurrent execution of transactional internetware applications under relaxed isolation. In this paper， a novel concurrency control method TSCM-CC（Transactional Service Composition Model-Concurrency Control） is proposed to coordinate the interleaving of concurrent transactions dynamically. First， the dependencies among transactions are classified into several types according to the transactional properties of involved services. Then a set of rules are proposed to confine the forming of dependencies， and their correctness is proved. At last， a distributed coordination protocol is designed to implement these rules. Compared to existing works， the most distinguished advantage of the method is that it can ensure a conflict-serializable execution under relaxed isolation while remain the relaxed atomicity of each transactional internetware application.

Key words: internetware, service composition, relaxed isolation, dependency, concurrency control

摘要： 网构软件是指导Internet环境下协作式软件开发的一种新的软件范型，网构应用可以通过组合Internet上已有的web服务来方便地进行构造。事务机制是保障网构应用可靠性的重要技术。web服务的自治性及网构应用的长时间运行特性使得事务间的隔离性必须被放松，因而必须研究如何保障事务性网构应用在松弛隔离性下并发执行时的正确性。针对这一问题，提出了一种新的并发控制方法TSCM-CC（事务性服务复合模型-并发控制）来协调并发事务的相互影响。首先，根据依赖双方服务的事务特征对事务间依赖的类型进行细分；然后，提出了一系列的规则来限制依赖的动态形成，并证明了这些规则的正确性；最后，给出了这些规则的一个分布式的协调协议的实现机制。此方法的最大特色在于能够在保持各个事务性网构应用松弛原子性的同时保证松弛隔离性下并发执行的正确性。

关键词: 网构软件, 服务组合, 松弛隔离性, 依赖, 并发控制