Service-oriented architecture (SOA) is gaining more and more momentum in today's software engineering, for its ease of integrating heterogeneous systems. Web services allow for building complex and dynamic systems where single components can be discovered at run-time by means of certain criteria like Quality of Service (QoS) information. QoS-aware service management and composition highly depends on this valuable data, but most of the currently proposed solutions assume that this information is readily available. This book addresses this fundamental issue by providing methods to monitor the performance of WCF Web services and composite Web services - also called workflows. The proposed solutions integrate into the Microsoft Windows and .NET environment and provide highly accurate QoS data, which can be used by third party workflow engines to dynamically bind to and invoke Web services.