On Integrating OCL and Triple Graph Grammars

Abstract

Triple Graph Grammars (TGGs) tend to be a promising approach for explaining relationships between models in general, and model co-evolution and model consistency within model-driven development in particular. Declarative TGG descriptions can be translated into operational scenarios for model integration, model synchronization, and model transformation. To realize such scenarios, restrictions formulated with the Object Constraint Language (OCL) are an important factor. How to integrate TGGs and OCL is a topic of ongoing research activities. There are strong similarities between the result of such an integration and the Queries, Views and Transformations (QVT) standard of the Object Management Group (OMG). We propose a language for this integration: One part of this language has a one-one mapping to TGGs and the remaining part covers OCL concepts. The language is realized in our tool UML-based Specification Environment (USE) by taking two views on operations derived from TGG rules: Declarative OCL pre- and postconditions are employed as operation contracts, and imperative command sequences are taken as an operational realization. USE offers full OCL support for restricting models and metamodels with invariants, for checking pre- and postconditions of operations as well as for validating and animating transformation operations. Our approach covers a complete realization of TGGs incorporating OCL within our tool USE.