Whenever autonomous entities work together to meet each other's needs, there arises the problem of how an entity with a need can find and use entities with the capability to meet that need. This problem is seen in Web service architectures, agent systems, and data integration systems, among others. Solutions have been proposed in each of these fields, but they are all dependent on implementation and interface. Hence all are restricted to their particular field, and all require their participants to conform to certain assumptions about implementation and interface. This failure of support for service autonomy is conceptually unattractive and impractical. In this thesis we show how to describe and matchmake service capabilities and client needs in a way that is implementation and interface independent. The result is a service discovery solution that fully supports the rights of services to choose their own implementation and interface. Our representation is capable of capturing capabilities across a range of service types, from Web services to agents to data sources, while ignoring the implementation and interface details that distinguish them. Thus, our solution unifies these fields for description and discovery purposes, allowing data sources with complex language interfaces to compete against form-based Web services and frame-and-slot agents, for example. Moreover, our solution captures all of the most important aspects of capability, such as: the conceptual meaning and limitations on what a service can achieve; what requests can be expressed through a service's interface, and limitations on what attributes of information a service can return. The provision of an interface independent capability description raises the additional question of how to enable a client to invoke the service to which it has been matched, and correctly interpret the results returned; we solve this by providing an interface description that maps from client objectives onto invocations, and from returned results onto a canonical result format.

Whenever autonomous entities work together to meet each other's needs, there arises the problem of how an entity with a need can find and use entities with the capability to meet that need. This problem is seen in Web service architectures, agent systems, and data integration systems, among others. Solutions have been proposed in each of these fields, but they are all dependent on implementation and interface. Hence all are restricted to their particular field, and all require their participants to conform to certain assumptions about implementation and interface. This failure of support for service autonomy is conceptually unattractive and impractical. In this thesis we show how to describe and matchmake service capabilities and client needs in a way that is implementation and interface independent. The result is a service discovery solution that fully supports the rights of services to choose their own implementation and interface. Our representation is capable of capturing capabilities across a range of service types, from Web services to agents to data sources, while ignoring the implementation and interface details that distinguish them. Thus, our solution unifies these fields for description and discovery purposes, allowing data sources with complex language interfaces to compete against form-based Web services and frame-and-slot agents, for example. Moreover, our solution captures all of the most important aspects of capability, such as: the conceptual meaning and limitations on what a service can achieve; what requests can be expressed through a service's interface, and limitations on what attributes of information a service can return. The provision of an interface independent capability description raises the additional question of how to enable a client to invoke the service to which it has been matched, and correctly interpret the results returned; we solve this by providing an interface description that maps from client objectives onto invocations, and from returned results onto a canonical result format.