A Declarative Extension of IDL-based Type Definitions within Open Distributed Environments

An open distributed environment can be perceived as a service market where services are freely offered and requested. Any infrastructure which seeks to provide appropriate mechanisms for such an environment has to include some mediator functionality to bring together matching service requests and service offers. The matching algorithm that the mediator must perform commonly builds upon an IDL-based type definition for service specification. In order for the matching algorithm embedded in this mediator to succeed, the types of various services have to be standardized and distributed to all interested parties. We argue that those well defined "standards" 2 are too inflexible and even contradict the idea of an open service market. Therefore we propose a new way to augment an arbitrary IDL-based type definition by a semantic tag. Whereas several other authors have used pre- and post-conditions to add the notion of behavior description, we use the well established field of Horn clauses as..