The term `open distributed processing' does not currently have a single, commonly accepted interpretation. Therefore, the main system architecture models are critically analysed in order to contrast the facilities for interoperation in each model. The focus of this dissertation is on the problems arising when the interoperating computing systems are controlled by autonomous organisations, i.e., problems of federated systems. Federations between sovereign systems involve exploitation of open interfaces and run-time information about the system facilities. Open systems, especially federated systems, must be based on a shared, very high level architecture model. The Open Distributed Processing (ODP) framework standard has been developed to enable world-wide computing services to evolve. Among other specifications, the family of ODP standards also identifies a set of fundamental services required from each participating system.

The trading service is one of the essential meta-information services of open systems. Trading presents a global mediator for information about available services and their properties. This dissertation presents work on the provision of the trading functionality. It analyses the requirements of trading designs and the ways trading function interacts with the system environment. The focus of this study is on federated trading, but trading problems in traditional distributed environments are also discussed. Furthermore, the design, implementation and performance of the DRYAD trading system is presented. In addition, exploitation scenarios for trading functionality in open distributed environments are analysed. Special attention is given for the use of trading in the explicit exchange, negotiation, and contract establishment required for interoperation in federated environments.

The trading functionality is a powerful tool to be used within the open infrastructure to support controlled cooperation between autonomous organisations. It allows construction of a world-wide computing environment that tolerates the constant evolution of services and applications. The exploitation of such a world-wide system requires software engineering tools that are based on the open system services. Therefore, major changes are expected in the areas of application architectures and software development processes within the next few years.