Constraint validation support in visual model transformation systems

Model-Driven Architecture (MDA) standardized by OMG facilitates to separate the platform independent part and the platform specific part of a system model. Due to this separation Platform-Independent Model (PIM) can be reused across several implementation platforms of the system. Platform-Specific Model (PSM) is ideally generated automatically from PIM via model transformation steps. Because of the appearance of high level languages, object-oriented technologies and CASE tools, metamodeling becomes more and more important. Metamodeling is one of the most central techniques both in design of visual languages, and reuse existing domains by extending the metamodel level. The creation of model compliers on a metamodeling basis is illustrated by a software package called Visual Modeling and Transformation System (VMTS), which is an n-layer multipurpose modeling and metamodel-based transformation system. VMTS is able to realize an MDA model compiler. This paper (i) addresses the relationship between the constraints enlisted in metamodel-based rewriting rules and the pre- and postconditions, (ii) it introduces the concepts of general validation, general preservation and general guarantee, which facilitate that if a transformation step is specified adequately with the help of constraints, and the step has been executed successfully for the input model, then the generated output model is in accordance with the expected result, which is described by the transformation step refined with the constraints. An illustrative case study based on constraint specification in rewriting rules is also provided.