OCL 2.0: Implementing the Standard

Abstract

Abstract OCL 2.0 is the newest version of the OMG’s constraint language to accompany their suit of Object Oriented modelling languages. The use of OCL as an accompanying constraint and query language for modelling with these languages is essential. As tools are built to support the modelling languages, it is also necessary to implement the OCL. This paper reports our experience of implementing OCL based on the latest version of the OMG’s OCL standard, UML models and MDA [17] techniques supported by the Kent Modelling Framework (KMF) [12], developed at the University of Kent. We provide an efficient LALR grammar for parsing the language and describe an architecture that enables the language to be bridged to any other modelling framework or tool. We also provide both syntactic and semantic models, which were used as inputs for KMFStudio [12] in order to generate Java code. In addition we give feedback on problems and ambiguities discovered in the standard, with some suggested solutions. 1 Introduction/Motivation The Object Constraint Language (OCL) [16] is a textual language, especially designed for use in the context of diagrammatic languages such as the UML. OCL was added to UML, as it turned out a visual diagram-based language is limited in its expressiveness. For instance, although the UML is powerful and covers many important situations, it is often not sufficient to describe certain important constraints. Using natural language on the one