The dramatic reductions in digital-technology costs, the new opportunities for multi-media communication, new common-carrier data networks and local area networks, as well as the progress in programming techniques provide both new opportunities and challenges in the usage of computer systems. The challenges tend towards a greater distribution of function through the network, with associated architectural needs. The paper concentrates on the components which are necessary to extend a communication subsystem to a comprehensive support system for distributed processing in a heterogeneous multi-vendor environment. Major components are services for distributed invocation, for directories and for security. Known solutions are discussed and some open problems are identified.