OLOTOS : analysis and extension of LOTOS for object - oriented specification

Abstract

The object-oriented paradigm is applied to a standard formal description technique LOTOS for the specification of distributed processing. The object-oriented paradigm is characterized by the major object-oriented concepts, class template, class, type, encapsulation, inheritance, and polymorphism. These major object-oridnted concepts are incorporated into two parts, process algebra and abstract data type of LOTOS. In general, it is called the object-oriented LOTOS. As approaches to object-oriented LOTOS, we first analyzed the object-orientedness that is inherent in LOTOS. In process algebre, the process definition is recognized as a class template. The instantiation of a process definition is an instance or an object. The set of instances is defined as the class. The inheritance mechanism is established by the conformance relationship between classes. Particularly, the extension relationship being one of the conformance relationships is used as the partial ordering relationships for the inheritance mechanism. In abstract data type, the type definition is recognized as a class template and a data item as an instance. A data sort is regarded as a class. The inheritance mechanism is defined by the enrichment relationships which also corresponds to the extension relationships of the conformance relationship. Secondly, we analyzed the introduction of an enhanced feature to solve the problem in the inheritance mechanism which is inherent in LOTOS. The problem is that the self-reference in a superclass must be preserved in a subclass. Thus, we proposed the derived process instantiation mechanism as a solution to the problem. In the result, the inheritance mechanism provides for both the class and type hierarchies in the evolutionary process of a specification. Thirdly, an object-oriented approach to specifications was developed through a small scale specification of the sieve object, as defined in the OSI/Network Management Forum Application Services. This work demonst...