What is an Object, After All?
Amı́lcar Sernadas, Hans-Dieter Ehrich · 1990
The envisaged notion of object is presented as corresponding to the basic, universal building block of (information) systems. A simple mathematical model for fully concurrent objects (actors) is adopted that extends a suitable model for sequential processes. An object is defined as a process possibly endowed with initiative and tracedependent attributes. Transactional requirements are analysed within this framework as liveness requirements. Object aggregation is explained using the general notion of object morphism. The basic inheritance, overriding and reification mechanisms are also presented, as well as a suitable notion of object-type. The computational model is shown through examples to provide a sound basis for (information) systems design, including abstract conceptual modeling and layered implementation of both passive (record-like) and active (procedure-like) objects. The model establishes a suitable semantic domain for the envisaged broad spectrum specification/design languag...