Interpreting ODP Viewpoint Specification: Observations from a Case Study

Open Distributed Processing (ODP) is a framework for specifying open distributed systems, under development by the International Standards Organisation (ISO). It is based on the general idea of viewpoints - i.e. partial specifications of an overall system, from different perspectives - but assumes five specific, named viewpoints, which are described informally in the ODP Reference Model (RM-ODP). This paper summarises some observations regarding an attempt to use ODP to specify a complex air traffic control system. Some of the key issues that arise are discussed further in the context of the formal specification of a simpler, idealised model, involving two formalised viewpoints - the Information Viewpoint (a high-level, abstract specification, in Z), and the Computational Viewpoint (a specification of distributed components and objects, in Object-Z).