Improving Requirements Engineering: An Enhanced Requirements Modelling and Analysis Method

Inadequate requirements engineering is considered to be one of the top causes of software development project failure today. One of the major problems is the lack of processes, techniques and automated tool support available to developers for specification methodology by enhancing the approach that is most popular at the moment - use case modelling. Despite their popularity, use case models lack structure and precision, which makes formal analysis of such models impossible. In our proposal, we amend traditional use case models with formal structure and semantics to make them suitable for automayed analysis. The enhanced use case modelling method that we propose is called Susan ("S"ymbolic "us"e case "an"alysis), whcih facilitates anaysis of use case models using model checking. We also developed a software tool called SusanX to construct, manipulate and analyse Susan models. The analysis feature of the tool is implemented using publicly available NuSMV model checker, which allows verification of finite state systems for behavioural properties expressed in temporal logic. A number of generic properties that can be used for verification of any Susan model are built into the SusanX tool. Additionally, SusanX permits the user to define model-specific properties for verification. This is done through property specification patterns, which allow one to express logic properties without knowing the details of the underlying formalism. In order to evaluate how valuable Susan and the SusanX tool are in solving real world problems, we performed a case study of a Cash Management System (CMS). The case study was done in collaboration with an established South African software development company, which provided use with the requirements specifications for the system. We successfully used the Susan notation to model the CMS requirements and performed various analyses on the models with SusanX. The state of requirements specifications was considerably improved through this process and numerous errors were discovered during the SusanX analyses

Analysis of Structured Use Case Models through Model Checking

Inadequate requirements specification remains to be one of the predominant causes of software development project failure today. This is mainly due to the lack of suitable processes, techniques and automated tool support available for specifying and analysing system requirements. In this paper we suggest a way to improve the approach to requirements specification that is the most popular at the moment - use case modelling. Despite their popularity, use case models are not adequate for creating comprehensive and precise requirements specifications. We amend the traditional use case metamodel such that more formal and structured models can be built. Further, we define several analysis schemes for these structured use case models that assist in discovering inconsistencies and other errors in the models. These analysis schemes are automated in a tool that we developed called the Structured Use case Model Analyser (SUM Analyser). The SUM Analyser provides an accessible interface that allows the user to construct use case models, configure and execute several analysis options and view the produced results. The existing NuSMV model checker is used to perform the actual verification tasks for the analysis. To facilitate this, the SUM Analyser transforms use case models to NuSMV programs and also interprets the produced results so that they can be understood by the user