Instance Generation from Type Graphs with Arbitrary Multiplicities

Meta modeling is a wide-spread technique to define visual languages, with the UML being the most prominent one. Despite several advantages of meta modeling such as ease of use, the meta modeling approach has a major disadvantage: It does not offer a direct means for generating its language elements. This disadvantage poses a severe limitation on certain applications. For example, when developing model transformations, it is desirable to have enough valid instance models available for large-scale testing. Producing such a large set by hand is tedious. In the related problem of compiler testing, a string grammar together with a simple generation algorithm is typically used to produce words of the language automatically. In this paper, we formalize a restricted form of meta-models by type graphs with multiplicities and introduce instance-generating graph grammars for creating instance graphs representing the abstract syntax structures of models. Thereby, a further step is taken to overcome the main deficit of the meta-modeling approach

What Algebraic Graph Transformations Can Do For Model Transformations

Model transformations are key activities in model-driven development (MDD). A number of model transformation approaches have emerged for different purposes and with different backgrounds. This paper focusses on the use of algebraic graph transformation concepts to specify and verify model transformations in MDD

Avoiding Unnecessary Information Loss: Correct and Efficient Model Synchronization Based on Triple Graph Grammars

Model synchronization, i.e., the task of restoring consistency between two interrelated models after a model change, is a challenging task. Triple Graph Grammars (TGGs) specify model consistency by means of rules that describe how to create consistent pairs of models. These rules can be used to automatically derive further rules, which describe how to propagate changes from one model to the other or how to change one model in such a way that propagation is guaranteed to be possible. Restricting model synchronization to these derived rules, however, may lead to unnecessary deletion and recreation of model elements during change propagation. This is inefficient and may cause unnecessary information loss, i.e., when deleted elements contain information that is not represented in the second model, this information cannot be recovered easily. Short-cut rules have recently been developed to avoid unnecessary information loss by reusing existing model elements. In this paper, we show how to automatically derive (short-cut) repair rules from short-cut rules to propagate changes such that information loss is avoided and model synchronization is accelerated. The key ingredients of our rule-based model synchronization process are these repair rules and an incremental pattern matcher informing about suitable applications of them. We prove the termination and the correctness of this synchronization process and discuss its completeness. As a proof of concept, we have implemented this synchronization process in eMoflon, a state-of-the-art model transformation tool with inherent support of bidirectionality. Our evaluation shows that repair processes based on (short-cut) repair rules have considerably decreased information loss and improved performance compared to former model synchronization processes based on TGGs.Comment: 33 pages, 20 figures, 3 table

Towards Translating Graph Transformation Approaches by Model Transformations

Recently, many researchers are working on semantics preserving model transformation. In the field of graph transformation one can think of translating graph grammars written in one approach to a behaviourally equivalent graph grammar in another approach. In this paper we translate graph grammars developed with the GROOVE tool to AGG graph grammars by first investigating the set of core graph transformation concepts supported by both tools. Then, we define what it means for two graph grammars to be behaviourally equivalent, and for the regarded approaches we actually show how to handle different definitions of both - application conditions and graph structures. The translation itself is explained by means of intuitive examples

Parallel Graph Transformation for Model Simulation applied to Timed Transition Petri Nets

Proceedings of the Workshop on Graph Transformation and Visual Modelling Techniques (GT-VMT 2004)This work discusses the use of parallel graph transformation systems for (multi-formalism) modeling and simulation and their implementation in the meta-modeling tool AToM3. As an example, a simulator for Timed Transition Petri Nets (TTPN) is modeled using parallel graph transformation.This work has been partially sponsored by the SEGRAVIS network and the Spanish Ministry of Science and Technology (TIC2002-01948)

Sufficient Criteria for Applicability and Non-Applicability of Rule Sequences

In several rule-based applications using graph transformation as underlying modeling technique the following questions arise: How can one be sure that a specific sequence of rules is applicable (resp. not applicable) on a given graph? Of course, it is possible to use a trial and error strategy to find out the answer to these questions. In this paper however, we will formulate suitable sufficient criteria for applicability and other ones for non-applicability. These criteria can be checked in a static way i.e. without trying to apply the whole rule sequence explicitly. Moreover if a certain criterion is not satisfied, then this is an indication for reasons why rule sequences may or may not be applicable. Consequently it is easier to rephrase critical rule sequences. The results are formulated within the framework of double pushout (DPO) graph transformations with negative application conditions (NACs)

Co-Transformation of Type and Instance Graphs Supporting Merging of Types and Retyping

Algebraic graph transformation is a well-known rule-based approach to manipulate graphs that can be applied in several contexts. In this paper we use it in the context of model-driven engineering. Graph transformation rules usually specify changes to only one graph per application, however there are use cases such as model co-evolution where not only a single graph should be manipulated but also related ones. The co-transformation of type graphs together with their instance graphs has shown to be a promising approach to formalize model and meta-model co-evolution. In this paper, we extend our earlier work on co-evolution by allowing transformation rules that have less restrictions so that graph manipulations such as merging of types and retyping of graph elements are allowed

A Formal Resolution Strategy for Operation-Based Conicts in Model Versioning Using Graph Modications

In model-driven engineering, models are primary artifacts and can evolve heavily during their life cycle. Hence, versioning of models is a key technique which has to be offered by an integrated development environment for model-driven engineering. In contrast to textbased versioning systems, our approach takes abstract syntax structures in model states and operational features into account. Considering the abstract syntax of models as graphs, we define a model revision by a span G H, called graph modification, where G and H are the old and new versions, respectively, and D the common subgraph that remains unchanged. Based on notions of behavioural equivalence and parallel independence of graph modifications, we are able to show a Local-Church- Rosser Theorem for graph modifications. The main goal of the paper is to handle conflicts of graph modifications which may occur in the case of parallel dependent graph modifications. The main result is a general merge construction for graph modifications that resolves all conflicts simultaneously in the sense that for delete-insert conflicts insertion has priority over deletion