Research On Dynamic Discovery And Composition Of Services With QoS Constraint

Service-oriented architecture (SOA) was first described by Gartner in the middle of 1990s. At present, although SOA has successfully been applied by many companies, the discovery of compound service and the assessment of the Quality of Service (QoS) are far from being satisfactory. We address these two problems by the following solutions:First, a model of discovering compound service based on observer pattern.In this model, all of those services and all their input variables are mapped into the corresponding objects in a domain model, within which the object of the service is responsible for observing all the objects of the input variables, while in return the object of the service is observed by all the objects of the outputs. And in every object there is a list which maintains all the possible paths that could reach this object. Proper compound service can be discovered by this method.Second, an over-all customizable platform for assessing QoS.There is no such an assessing algorithm that meets all the demands from users. So we provide an over-all customizable platform and five algorithms for default, upon which users can choose one of them or they can customize their own assessing curve most suitable for selecting the service they want.