Analysis of coexisting graphical and textual representations of requirements based on activity diagrams and structured text
Martin J. Beckmann · 2019
Due to increasing complexity and the tendency towards more customized products, the development of modern technical systems demands more and more effort. In an attempt to reduce the effort required, engineering models are being adopted to a greater extent in all phases of development. Among the affected development phases is requirements engineering. As a result, engineering models, which almost always take the form of graphical notation, have become more common in a setting where text-based requirements specifications have been historically predominant. These graphical models are not a replacement for text-based specifications, but supplement them instead. While these two forms of representation may be complementary, oftentimes they are strongly related or even express the same content. Hence, the graphical and textual representations coexist. The use of coexisting graphical and textual representations for specification purposes has shown promising results. However, these results have been obtained in a research context and are at best evaluated in practice. In practice however, such approaches are tailored to domain- or even project-specific needs. It is unclear whether comparable approaches implemented by practitioners independently achieve the same promising results as those obtained in research contexts. In this thesis, we address this gap by examining a case where an approach using coexisting graphical and textual representations is realized and productively used by practitioners. The specific realization of this approach employs UML2 Activity Diagrams as graphical representation and hierarchically structured text as textual representation to describe the functions of a system. From the results of this examination, we conclude that, for the most part, the practitioners perceive the benefits of this approach as predicted by research. Still, the application of such an approach in practice results in a number of pitfalls. Inconsistencies between the two representations, as well as other quality issues, constitute the biggest impact on the practical usability of this approach. Over 70% of the functions are affected by deficiencies that are considered major issues by users. As these deficiencies represent a sizable negative impact on the applicability of the approach, a method is developed in this thesis that prevents the occurrences of inconsistencies and other quality issues. Overall, this thesis contributes to the body of knowledge of approaches that use an additional textual representation with graphical models. This knowledge may be employed to design new approaches or improve existing ones in order to increase acceptance among practitioners.