Behavior Preservation in Model Refactoring Using DPO Transformations with Borrowed Contexts

Abstract

Abstract. Behavior preservation, namely the fact that the behavior of a model is not altered by the transformations, is a crucial property in refactoring. The most common approaches to behavior preservation rely basically on checking given models and their refactored versions. In this paper we introduce a more general technique for checking behavior preservation of refactorings defined by graph transformation rules. We use double pushout (DPO) rewriting with borrowed contexts, and, exploiting the fact that observational equivalence is a congruence, we show how to check refactoring rules for behavior preservation without the need of considering specific models. When rules are behavior-preserving, their application will never change behavior, i.e., every model and its refactored version will have the same behavior. However, often there are refactoring rules describing intermediate steps of the transformation, which are not behavior-preserving, although the full refactoring does preserve the behavior. For these cases we present a procedure to combine refactoring rules to behavior-preserving concurrent productions in order to ensure behavior preservation. An example of refactoring for finite automata is given to illustrate the theory.

Formal Verification Techniques for Model Transformations: A Tridimensional Classification .

“…Among others, Abstract State Machines provide Ctl model-checking by using another mapping into the Spin modelchecker (used in the Asmeta framework [44]), and Maude has been the verification target for several works, providing reachability analysis, theorem-proving by mapping Maude specification into Isabelle/Hol, and Ltl model-checking: the approach was used for verifying visual Dsls whose behavioural semantics is expressed using Gbt in single/double pushout styles [98,100], and by Barbosa et al [8] for proving a relatively simple form of semantic preservation on Java imperative programs by comparing the resulting semantic domains (note that this last work uses a three-lines Java example whose scalability is questionable since none of the challenging Java constructionconditional and loop statements, but also casting and method calls -are handled). Rangel et al [95] proposed a framework for preserving the behaviour of refactorings in a Gbt framework using borrowed contexts that works both at the rule and the transformation levels.…”

“…A preservation expresses patterns at a syntactic level [46,70,85], or formulas at a semantic level [114] that need to be proved equivalent (in a given sense) through the transformation. Behavioural properties use safety properties that should hold on the transformation execution [8,11,23,44,68,86,95,98,100]. Figure 7 places some of the contributions reviewed in Structural [1,79,81] .…”

Embedding domain-specific modelling languages in maude specifications

“…Among the many related works, graph transformations are formal modelling languages that have been used for defining semantics of DSML and of model transformations [12,13,14], including semantics-preserving model transformations [15,16]. An advantage of using Maude with respect to these approaches is that they abstract away from attribute values, whereas Maude does not.…”

Saturated LTSs for Adhesive Rewriting Systems

“…We also presented barbed semantics for ARSs: they are needed to address the semantics of many process calculi, such as asynchronous ccs and mobile ambients, but their application could be wider. For instance, [28] studies model refactoring that preserves GIPO bisimilarity: the latter could be safely replaced by barbed saturated bisimilarity. Our work also opens new venues of investigation.…”

“…Despite validating case studies [28], so far the boundaries of the BC framework were less tested and extended. The resulting lack of flexibility is clearly a drawback in terms of BCs usability, yet it casts a shadow also on the novel notions introduced for GRSs: indeed, these are of an eminently prescriptive nature, and they would then benefit (as a sanity check, or for clarifying their meaning) from the constructive recasting offered by the BC setting.…”