Abstract: Web service composition enables a new way to create new services by assembling independent service components. One of the important goals in service composition was analyzed aiming at reliability and performance attributes of service compositions. In this paper,a novel evaluating method based on DTMC(Discrete Time Markov Chain) was presented to solve this problem. By applying properties and formulas derived from the theory of DTMC, this method comprehensively estimated reliability and performance attributes of service compositions in view of different execution scenarios. It also assisted in identifying bottlenecks of given service compositions and suggesting strategics for improve-menu. Compared with previous researches, this method not only analyzed reliability and performance attributes more accurately,but also adapted better to complex structures and multiple execution scenarios which are distinct characteristics of service compositions. Experiments show that it has a good ability in terms of reliability and performance analysis of Web service composition.

Key words: Service compositions,Refiabifity analysis,DTMC, Execution scenarios