On interfaces

The nature of interfaces is discussed. It is recommended that modern software approaches to interfaces (such as abstract data types) be extended to interfaces of all kinds. These interfaces can and should be developed at the level of abstraction appropriate to the interacting elements, rather than at the level of their lowest common denominator, which is frequently the case. It is proposed that for an interface to exist at any level of abstraction, there must be an operational framework that implements that level of abstraction and within which the interfacing elements interact. Four tasks required for the development of interfaces are described. The traditional classification of interfaces as hardware/software, software/software, and hardware/hardware is found wanting and a new partitioning is suggested—structural or interpretive interfaces, symbolic interfaces, and physical interfaces. Standards and scientific and engineering theories are shown to define levels of abstraction for general interfaces in much the same way that programming languages do for software interfaces. Implications for software engineering and concurrent engineering are explored.