A Metamodel Independent Approach to Difference Representation.

Abstract

It is of critical relevance that designers are able to comprehend the various kinds of design-level modifications that a system undergoes throughout its entire lifecycle. In this respect, an interesting and useful operation between subsequent system versions is the model difference calculation and representation. In this paper, a metamodel independent approach to the representation of model differences which is agnostic of the calculation method is presented. Given two models which conform to a metamodel, their difference is conforming to another metamodel derived from the former by an automated transformation. Difference models are first-class entities which induce transformations able to apply the modifications they specify. Finally, difference models can be composed sequentially and in parallel giving place to more complex modifications.

A Solution for Concurrent Versioning of Metamodels and Models.

“…In fact, current techniques typically adopt "tagging" mechanisms of model elements (notably added, updated, deleted) that do not make differences context-independent. In other words, the approaches need to carry extra-information about the involved artefacts to allow an appropriate interpretation of the evolution [CDP07]. Such need hinders, for instance, the exploitation of patching techniques, since differences are difficult to abstract from the detection context.…”

“…As discussed in [CDP07], the differences representation approach enjoys a number of interesting properties that allow the appropriate versioning of models and the retrieval of previous revisions; nonetheless, as an immediate consequence of dealing with a mixture of models conforming to different metamodels a problem arises because of the incomparability between concurrent revisions. In particular, by recalling the scenarios described in Section 4, manipulations made on the repository and the ones locally operated may pertain to different languages, i.e., DiffMM a and DiffMM b , respectively.…”

“…Such representation is based on an enriched version of an existing work [CDP07] which introduced a technique for the storage of model evolution relying on the partitioning of the manipulations into three basic operations: additions, deletions, and updates of model elements. Since a metamodel is a model itself, it is possible to adopt the same mechanism also for the representation of metamodel evolution, as already clarified in [CDP09]; therefore, we will generically write about metamodels and models taking into account that in the case of metamodel evolutions the metamodel plays the role of the model and its metamodel is the metametamodel.…”

“…Since the contemporary revision of both languages and models carries further problems that have to be considered, the discussion contained in this article is based on the assumption that the language is explicitly versioned, meaning that in the repository both model and metamodel revisions are available. Moreover, due to memory and performance costs the evolution is stored in terms of differences between subsequent versions, whereas (as typically happens for source code) only the newest is kept as the (meta)model as a whole [CDP07].…”

From State- to Delta-Based Bidirectional Model Transformations

“…Another typical way to implement deltas is to present them operationally as sequences of edit operations [CRP07], and some differencing tools work in this mode [AP03, AAAN + 08].…”