SCTL-MUS: A formal methodology for software development of distributed systems. A case study

Abstract

This paper introduces an iterative model for the software development process of distributed systems. It is based on dealing with the system evolution and maintenance activities as similar stages of the system development. In order to formalise this model, a multi-valued causal temporal logic, referred to as Simple Causal Temporal Logic (SCTL), is defined for the acquisition and specification of the functional requirements. A Model of Unspecified States (MUS) is also defined with a double goal: firstly, to show the fundamental aspects of system behaviour, which has been specified through a set of SCTL requirements; and, secondly, to verify the consistency and completeness of the specified requirements. The combination of SCTL and MUS allows obtaining the specification of the initial architecture of the system formally. Besides, the design decisions are stored with the goal of making the evolution and maintenance tasks easier. The translation between MUS and a constructive formal description technique (LOTOS) is automatic from the definition of architectural operators.