CAViT: a Consistency Maintenance Framework based on Transformation Contracts

Model driven engineering is a software engineering methodology that aims to manage the complexity of frameworks by relying on models and transformations. Unfortunately it is only poorly understood where and how this new methodology differs from traditional methodologies. Therefore, this paper formalizes how contract based model transformation extends existing design by contract theory. The key extension is that transformation contracts can be maintained automatically by mapping consistency invariants to the postconditions of transformation rules. When an invariant is violated, the corresponding transformation rule will be called provided that its precondition is satisfied. This paper presents the Contract Aware Visual Transformation (CAViT) framework, an implementation of declarative middleware for contract based model transformation. We illustrate how CAViT can be used to integrate UML based visual model transformations with OCL based transformation contracts.