Although the interoperability among systems can be achieved through the use of well-de ned interfaces to services, communication between the blocks of SOA needs to be done so that at least some form of quality of service may be offered to the client of the service, be that a Web client, another service or a set of services. The architecture model proposed in this book should enable better provision of quality of service among the messages exchanged among applications. The main focus of the WSARCH, which makes it different from other architectures, is the fact that it is an architecture focused on the assessment and delivery of performance considering QoS attributes. Thus, for the development of WSARCH it is important to identify and map the QoS attributes of the various components of a service-oriented architecture and in particular the proposed architecture. We hope that the performance evaluation of this architecture serves as a case study for enterprises, service providers, industry and government agencies that want to bene t from service-oriented computing as a way to integrate applications and business processes."