Research On Web Services Composition:Selection,Verification And Perception

Web services are an emerging and promising technology in distribution appli-cations by aggregating several existing services to build new value-added services. However, due to rapidly increasing number of available web services over Inter-net, web service registries need to construct a composite service to fulfill complex requirements in an efficient and cost-effective way. Meanwhile, services are of-ten long running, loosely coupled, and cross administrative boundaries, adapting transactionsl properties support in the composite services is also necessary. More over, in order to make service selection reasonable in an open environment, repu-tation has been regarded as one of the most important characteristic to identify good services from bad ones. However, a composite service, which is composed of multiple component services, only obtains one perception from the user after every invocation. In order to compute the reputation of each component ser-vice, it is necessary for the composite service to distribute this perception to its component services recursively. Therefore, how to select a batch of component services to construct a composite service to fulfill a complex requirement, verify this composite service’s transactional properties to ensure that it can always ter-minate correctly, and propagate the perception from the composite service to its component services fairly, becomes challenging and significant problems in web service composition.In this dissertation, we present a web services composition framework to address the problems of selection, verification, and perception by incorporating various techniques, including constructing skyline composite services, validating transactional properties of BPEL-composition, and propagating reputation from composite service to its component services. The main research works and con-tributions of this dissertation include the following: ·We propose a composition approach to construct all skyline candidate com-posite services for each individual request. And we also use a cluster-based grouping method to improve efficiency of constructing a set of skyline candi-date solutions. We evaluate the efficiency and effectiveness of our methods via synthetically generated datasets.·We present a technique to analyze the WS-BPEL process and other related files to validate whether this process complies with the expected transac-tional properties. We identify key points and risk points to help validate whether a process is well-formed. The validation technique can assess the correctness of WS-BPEL process specifications and therefore can help pro-cess designers to identify ill-formed processes·We propose a fair perception score distribution framework which combine the context of component services and their runtime performance. We dis tinguish two aspects of contexts of a component service, i.e.. structure related importance and community-related replaceability. and compute them by graph theory and dominating relationship technique, respectively. Ex-perimental results show that our approach can achieve a more reasonable and fair perception score distribution than other existing methods...