Bidirectional transformation

Macedo N, Cunha A, Pacheco H.  2014.  Towards a framework for multi-directional model transformations. 3rd International Workshop on Bidirectional Transformations - BX. 1133 AbstractPaper

The Query/View/Transformation Relations (QVT-R) standard for bidirectional model transformation is notorious for its underspecified semantics. When restricted to transformations between pairs of models, most of the ambiguities and omissions have been addressed in recent work. Nevertheless, the application of the QVT-R language is not restricted to that scenario, and similar issues remain unexplored for the multidirectional case (maintaining consistency between more than two models), that has been overlooked so far.
In this paper we first discuss ambiguities and omissions in the QVT-R standard concerning the mutidirectional transformation scenario, and then propose a simple extension and formalization of the checking and enforcement semantics that clarifies some of them. We also discuss how such proposal could be implemented in our Echo bidirectional model transformation tool.
Ours is just a small step towards making QVT-R a viable language for bidirectional transformation in realistic applications, and a considerable amount of basic research is still needed to fully accomplish that goal.
Macedo N, Pacheco H, Sousa NR, Cunha A.  2014.  Bidirectional Spreadsheet Formulas. VL/HCC - IEEE Symposium on Visual Languages and Human-Centric Computing. 6120 Abstractvlhcc14ss.pdf

Bidirectional transformations have potential applications in a vast number of computer science domains. Spreadsheets, on the other hand, are widely used for developing business applications, but their formulas are unidirectional, in the sense that their result can not be edited and propagated back to their input cells. In this paper, we interpret such formulas as a well-known class of bidirectional transformations that go by the name of lenses. Being aimed at users that are not proficient with programming languages, we devote particular attention to the seamless embedding of the proposed bidirectional mechanism with the typical workflow of spreadsheet environments, allowing users to have a fine control and understanding of the behavior of the derived backward transformations.
Pacheco H, Macedo N, Cunha A, Voigtländer J.  2013.  A Generic Scheme and Properties of Bidirectional Transformations. CoRR. arXiv/1306.4473:19. Abstract1306.4473v2.pdf

The recent rise of interest in bidirectional transformations (BXs) has led to the development of many BX frameworks, originating in diverse computer science disciplines. From a user perspective, these frameworks vary significantly in both interface and predictability of the underlying bidirectionalization technique. In this paper we start by presenting a generic BX scheme that can be instantiated to different concrete interfaces, by plugging-in the desired notion of update and traceability. Based on that scheme, we then present several desirable generic properties that may characterize a BX framework, and show how they can be instantiated to concrete interfaces. This generic presentation is useful when exploring the BX design space: it might help developers when designing new frameworks and end-users when comparing existing ones. We support the latter claim, by applying it in a comparative survey of popular existing BX frameworks.
Macedo N, Pacheco H, Cunha A.  2012.  Relations as executable specifications: taming partiality and non-determinism using invariants. :146-161. Abstractndlenses12tech.pdf

The calculus of relations has been widely used in program specification and reasoning. It is very tempting to use such specifications as running prototypes of the desired program, but, even considering finite domains, the inherent partiality and non-determinism of relations makes this impractical and highly inefficient. To tame partiality we prescribe the usage of invariants, represented by coreflexives, to characterize the exact domains and codomains of relational specifications. Such invariants can be used as pre-condition checkers to avoid runtime errors. Moreover, we show how such invariants can be used to narrow the non-deterministic execution of relational specifications, making it viable for a relevant class of problems. In particular, we show how the proposed techniques can be applied to execute specifications of bidirectional transformations, a domain where partiality and non-determinism are paramount.