CAViT: a Consistency Maintenance Framework based on Transformation Contracts

Design by contract is a software correctness methodology for procedural and object-oriented software. It relies on logical assertions to detect implementation mistakes at run-time or to proof the absence thereof at compile-time. Design by contract has found a new application in model driven engineering, a methodology that aims to manage the complexity of frameworks by relying on models and transformations. A ``transformation contract'' is a pair of constraints that together describe the effect of a transformation rule on the set of models contained in its transformation definition: the postcondition describes the model consistency state that the rule can establish provided that its precondition is satisfied. A transformation contract of a rule can be maintained automatically by calling the rule (1) as soon as the invariant corresponding to its postcondition is violated and (2) provided that its precondition is satisfied. Domain specific visual languages can facilitate the implementation of the actual transformation rules since they hide the complexity of graph transformation algorithms and standards for tool interoperability. In this talk, we describe CAViT: a framework that integrates a visual model transformation tool with a design by contract tool by relying on OMG standards such as UML, OCL and MOF.