On conformance in the context of open systems

Conformance is one of the key notions in the context of open systems and therefore must be precisely defined. Existing formalizations define conformance independently of the environment into which the open system will be embedded. It is argued that it is, in general, not adequate to guarantee conformance in an intuitive sense. Conformance should relate the visible behavior defined by two specifications, which conceptually occurs at external interaction points. Based on this assumption, an additional condition which is sufficient to overcome the difficulty is identified. The condition is based on compatibility between interaction points, a notion which is introduced and formally defined. An approach to verify this condition and some general results are presented. The application of this approach to open systems interconnection (OSI) is outlined