Implementing an OCL Compiler for .NET

Model-Driven Architecture standardized by OMG facilitates separating the platform-independent part (PIM) and the platform-specific part (PSM) of a system model. The platform-independent artifacts are mainly UML models created with CASE tools. Due to this separation, PIM specified by the developers can be reused across several implementation platforms of the software. PSM is ideally generated automatically from PIM via model transformation steps performed by model compilers. Beyond the topology of the visual models additional constraints must be specified, which ensure the correctness of the attributes among others. Dealing with OCL constraints provides a solution for the unsolved issues, because topological and attribute transformation methods cannot perform and express the problems that can be addressed by constraint validation. This paper discusses the need for combining UML and OCL, it introduces the compilers in general, it shows the architecture of our OCL Compiler for .NET, and it presents the lexical and syntactic analysis as well as the semantic analysis and code generation techniques in detail. The OCL Compiler has been implemented as a module of our n-layer multipurpose modeling and metamodel-based transformation system called Visual Modeling and Transformation System (VMTS). The OCL Compiler module facilitates validating (i) constraints contained by the metamodels at the time of the model instantiation process, and (ii) constraints contained by the transformation steps during the metamodel-based graph transformation. An illustrative case study is also provided, which introduces how VMTS generates source code from a statechart diagram, and how it validates specific properties using the OCL Compiler.