Diagram Definition: A Case Study with the UML Class Diagram

The abstract syntax of a graphical modeling language is typically defined with a metamodel while its concrete syntax (diagram) is informally defined with text and figures. Recently, the Object Management Group (OMG) released a beta specification, called Diagram Definition (DD), to formally define both the interchange syntax and the graphical syntax of diagrams. In this paper, we validate DD by using it to define a subset of the UML class diagram. Specifically, we define the interchange syntax with a MOF-based metamodel and the graphical syntax with a QVT mapping to a graphics metamodel. We then run an experiment where we interchange and render an example diagram. We highlight various design decisions and discuss challenges of using DD in practice. Finally, we conclude that DD is a sound approach for formally defining diagrams that is expected to facilitate the interchange and the consistent rendering of diagrams between tools.