QoS Assessment over Multiple Attributes

In an open service oriented computing environment, multiple providers may offer functionally identical services but with varying qualities. It is desirable therefore that we are able to assess the quality of a service (QoS), so that service consumers can be given additional guidance in selecting their preferred services. Various methods have been proposed to assess QoS using the data collected from monitoring tools, but they do not deal with multiple QoS attributes adequately. Typically these methods assume that the quality of a service may be assessed by first assessing the quality level delivered by each QoS attribute individually, and then aggregating them in some way to give an overall verdict for the service. In this paper, we show that this may lead to incorrect assessment, and suggest how existing methods may be improved to deal with multiple attributes more effectively.