A WSDL Extension for Performance-Enabled Description of Web Services

Abstract

Web services are the building blocks of the emerging computing paradigm based on service-oriented architectures. A web service is a self-describing, open component that supports rapid composition of distributed applications. Web service definitions are used to describe the service capabilities in terms of the operations of the service and the input and output messages for each operation. Such definitions are expressed in XML by use of the Web Service Definition Language (WSDL). Unfortunately, a WSDL description only addresses the functional aspects of a web service without containing any useful description of non-functional or quality of service characteristics. This paper addresses the performance attribute of quality of service and introduces a WSDL extension for the description of performance characteristics of a web service. The extension is carried out as a metamodel transformation, according to principles and standards recommended by the Model Driven Architecture (MDA). The WSDL metamodel is introduced and then transformed into the P-WSDL (Performance-enabled WSDL) metamodel. The proposed P-WSDL extension can effectively be used to specify performance requirements of web services, to describe performance data measured on given web services, to add performance-oriented characteristics when querying registries of web services, to ease the derivation of performance models of web services and to support the automated mapping from WSDL documents to P-WSDL ones and from UML models to P-WSDL web services.