Abstract:

A web service has many different QoS attributes. Different customers have different preferences on different QoS attributes of a web service. For getting a service which can best fit the customer’s desire, this paper gives a quantitative selection algorithm based on the weighted space distance in the n dimensions. Using the preferences, the algorithm calculates the firstorder weighted space distance of every service, and selects the best service named “a”; If the relative dispersion is greater than or equal to the threshold value, it returns service “a” to the customer. Or else, the algorithm calculates the secondorder weighted space distance of every service, and selects the best service named “b”; if the relative dispersion is greater than or equal to the threshold value, it returns service “b” to the customer. Otherwise the service returns to the customer is the one that has the large relative dispersion. This algorithm can select the best one from web services with the same performance, which sufficiently indicates the preferences, and thus has its obvious advantage.

Key words: QoS；space distance；web service；selection