Declarative Specification of Bidirectional Transformations Using Design Patterns

Bidirectional transformations (bx) are a specific form of model transformation (MT) used in model-driven engineering to maintain consistency between two models, which may change independently. Currently bx are defined using a number of specialized transformation languages, which have had limited uptake due to complex semantics and poor efficiency. In contrast, unidirectional transformation languages such as ATL have been widely adopted, but require separate forward and reverse transformations to be written to address model synchronization requirements. In this paper, we provide declarative specification techniques for bx, systematically constructed using MT design patterns. We define two approaches to declarative bx definition: 1) by automatically bidirectionalizing unidirectional transformation specifications and 2) by developing specification guidelines for the QVT-R standard language to make it more effective for bx in practice. The approaches are evaluated using a large-scale code-generator bx from UML to ANSI C and other examples. Their semantic validity is demonstrated by rigorous arguments.