CDDiff: Semantic Differencing for Class Diagrams

Abstract

Abstract. Class diagrams (CDs), which specify classes and the relationships between them, are widely used for modeling the structure of object-oriented systems. As models, programs, and systems evolve over time, during the development lifecycle and beyond it, effective change management is a major challenge in software development, which has attracted much research efforts in recent years. In this paper we present cddiff , a semantic diff operator for CDs. Unlike most existing approaches to model comparison, which compare the concrete or the abstract syntax of two given diagrams and output a list of syntactical changes or edit operations, cddiff considers the semantics of the diagrams at hand and outputs a set of diff witnesses, each of which is an object model that is possible in the first CD and is not possible in the second. We motivate the use of cddiff , formally define it, and show how it is computed. The computation is based on a reduction to Alloy. The work is implemented in a prototype Eclipse plug-in. Examples show the unique contribution of our approach to the state-of-the-art in version comparison and evolution analysis.

Extraction and evolution of architectural variability models in plugin-based systems

“…Model differencing is an important technique to manage (e.g., understanding, maintenance) evolutions of models. It has attracted research efforts in recent years, including the development of tools (e.g., see [51,37,44,44,42,43]). The bibliography [51] compiles about 300 publications in this field.…”

“…As argued in [44,26], models (e.g., FMs) that are syntactically very similar may induce very different semantics and a list of differences should be best addressed semantically. Recently, Maoz et al tackled the problem of semantic model differencing, specifically for class and activity diagrams [42,43]. They defined and implemented two versions of semantic diff operator, cddiff and addiff.…”

Feature Model Differences

“…While showing some success, there are serious limitations. Models that are syntactically very similar may actually have very different semantics (intended meaning), and vice versa, models that describe the same system may have very different syntactic representations [19,17,13]. This observation also applies to FMs [27].…”

“…Though the syntactic diff might be useful, we believe that a semantic diff for FMs should also be developed and possibly be combined with syntactic differencing. Many researchers share this vision (e.g., see [28,19,13]) and semantic differences have already been developed specifically for other kinds of models (class diagrams [17] and activity diagrams [18]). We present semantic differencing techniques in Section 3.2.…”

“…As a result, a list of syntactic differences, although accurate and useful, may not be able to reveal the real and meaning-ful implications these differences have on the models involved. Some voices are calling for more semantic differencing [19,13] and such techniques have recently emerged for specific modeling formalisms [17,18]. In the feature modeling community, Benavides et al do not report any differencing support in their survey, despite the impressive research effort on FM automations [7].…”