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With the development of theory and technology of web service, Web Service Composition has become the core Service-Oriented Computing technology. It is important for business process to select the best service components with multi-dimensional QoS assurance to construct a complex one. In this paper we propose a web service composition model with multiple QoS constraints. We define the utility function as the evaluation standard considering all QoS parameters of each service component and use Subjective-objective Weight Mode to set the weight of each QoS metric.

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Abstract. During the execution of Web Service Composition, if one component service fails or becomes overloaded not to be accessed, a failure recovery mechanism is needed to ensure that the running process is not interrupted and the failed service can be replaced quickly and efficiently. Recent researches on this problem have some disadvantages. They don't consider the influence of the number of service candidates or the connection state of the overlay network, so the algorithms are easily disabled. In this paper, we present an adaptive algorithm to find replacement path locally by virtue of the old path during dynamic service composition. We go backward along the execution path to find the branch node, and then construct the sub-graph by the predefined rules. Finally we choose the best path with the highest total utility to replace the failed one. The test's result shows the algorithm performs very well in the vigorousness and availability to dynamic adaptation.

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