UML Based Reverse Engineering for the Verification of Railway Control Logics

Abstract

The Unified Modeling Language (UML) is widely used as a high level object oriented specification language. In this paper we present a novel approach in which reverse engineering is performed using UML as the modelling language used to achieve a representation of the implemented system. The target is the core logic of a complex critical railway control system, which was written in an application specific legacy language. UML perfectly suited to represent the nature of the core logic, made up by concurrent and interacting processes, using a bottom-up approach and proper modeling rules. Each process, in fact, was strictly related to the management of a physically (resp. logically) well distinguished railway device (resp. functionality). The obtained model deeply facilitated the static analysis of the logic code, allowing for at a glance verification of correctness and compliance with higher-level specifications, and opened the way to refactoring and other formal analyses.

Modeling of Railway Logics for Reverse Engineering, Verification and Refactoring

“…An early application of UMl to the analysis of railway control logics has been described in [28], in which, however, the authors did not yet abstract the methodological aspects, which are necessary to generally and systematically integrate the approach in the life-cycle of industrial control systems.…”

Automatic instantiation of abstract tests on specific configurations for large critical control systems

“…Reference models are usually based on notations of the Unified Modelling Language (UML) [9]. UML is a de facto standard in software development (see Model Driven Engineering, [10]), but it can be also used for different purposes, like formal verification [11] and reverse engineering [12]. There exist several research works which deal with the automatic test generation from UML models [13].…”

“…This requires adopting an object-oriented or analogously structured design approach, in which physical and logical entities are mapped on corresponding processes, each one featuring its own attributes and operations. For existing systems which are not compliant to the reference architectural model, it would be necessary to review the design to determine whether it can be re-factored or re-engineered [12]. Although this may involve a good deal of effort, if many configurations are likely then the effort is more than offset by the savings achieved by the multiple application of the abstract testing method.…”