Abstract: Current evaluation methods of Web services do not consider the timcutility, while qualification of timcutility in other systems are hard to satisfy the requirements of distinction of decay of time utility. As a result, Web service evaluation model based on qualification of time utility was proposed. Based on forgetting phenomenon of time utility, the model analyzes the relationship between timcutility and memory, unfolds regular of update of forgetting-ratio to time utility, and designs method to qualify time utility concerned with the distinction of decay of time utility. Meanwhile, result of time utility is used to optimize calculation of length of evaluation widows, as to improve KNN in artificial setting of evaluation windows. Experiments shows that model meets the requirements of distinction of decay of time utility, achieves low evaluation error, reduces computational cost and fits users' evaluation, which is meaningful to theoretical research and practical use.

Key words: Web services,Scrvice evaluation,Qualification of time utility,Forgetting process,Evaluation windows