This book presents the design, implementation and validation of a value-added supportive infrastructure for Semantic Web based business application services across mobile and fixed networks, applied to an emergency healthcare application. This infrastructure has been realized by the CASCOM European research project. For end users, the CASCOM framework provides seamless access to semantic Web services anytime, anywhere, by using any mobile computing device. For service providers, CASCOM offers an innovative development platform for intelligent and mobile business application services in the Semantic Web. The essential approach of CASCOM is the innovative inter-disciplinary combination of intelligent agent, Semantic Web, peer-to-peer, and mobile computing technology. Conventional peer-to-peer computing environments are extended with components for mobile and wireless communication. Semantic Web services are provided by peer software agents, which exploit the coordination infrastructure to efficiently operate in highly dynamic environments. The generic coordination support infrastructure includes efficient communication means, support for context-aware adaptation techniques, as well as flexible, resource-efficient service discovery, execution, and composition planning. The book has three main parts. First, the state-or-the-art is reviewed in related research fields. Then, a full proof-of-concept design and implementation of the generic infrastructure is presented. Finally, quantitative and qualitative analysis is presented on the basis of the field trials of the emergency application.