Reusable model transformations

Model transformations written for an input metamodel may often apply to other metamodels that share similar concepts. For example, a transformation written to refactor Java models can be applicable to refactoring UML class diagrams as both languages share concepts such as classes, methods, attributes, and inheritance. Deriving motivation from this example, we present an approach to make model transformations reusable such that they function correctly across several similar metamodels. Our approach relies on these principal steps: (1) We analyze a transformation to obtain an effective subset of used concepts. We prune the input metamodel of the transformation to obtain an effective input metamodel containing the effective subset. The effective input metamodel represents the true input domain of transformation. (2) We adapt a target input metamodel by weaving it with aspects such as properties derived from the effective input metamodel. This adaptation makes the target metamodel a subtype of the effective input metamodel. The subtype property ensures that the transformation can process models conforming to the target input metamodel without any change in the transformation itself. We validate our approach by adapting well known refactoring transformations (Encapsulate Field, Move Method, and Pull Up Method) written for an in-house domain-specific modeling language (DSML) to three different industry standard metamodels (Java, MOF, and UML).     

Change-driven model transformations

In this paper, we investigate change-driven model transformations, a novel class of transformations, which are directly triggered by complex model changes carried out by arbitrary transactions on the model (e.g. editing operation, transformation, etc). After a classification of relevant change scenarios, we identify challenges for change-driven transformations. As the main technical contribution of the current paper, we define an expressive, high-level language for specifying change-driven transformations as an extension of graph patterns and graph transformation rules. This language generalizes previous results on live model transformations by offering trigger events for arbitrarily complex model changes, and dedicated reactions for specific kinds of changes, making this way the concept of change to be a first-class citizen of the transformation language. We discuss how the underlying transformation engine needs to be adapted in order to use the same language uniformly for different change scenarios. The technicalities of our approach will be discussed on a (1) model synchronization case study with non-materialized target models and (2) a case study on detecting the violation of evolutionary (temporal) constraints in the security requirements engineering domain.     

Towards the efficient development of model transformations using model weaving and matching transformations

Model transformations can be used in many different application scenarios, for instance, to provide interoperability between models of different size and complexity. As a consequence, they are becoming more and more complex. However, model transformations are typically developed manually. Several code patterns are implemented repetitively, thus increasing the probability of programming errors and reducing code reusability. There is not yet a complete solution that automates the development of model transformations. In this paper, we present a novel approach that uses matching transformations and weaving models to semi-automate the development of transformations. Weaving models are models that contain different kinds of relationships between model elements. These relationships capture different transformation patterns. Matching transformations are a special kind of transformations that implement methods that create weaving models. We present a practical solution that enables the creation and the customization of different creation methods in an efficient way. We combine different methods, and present a metamodel-based method that exploits metamodel data to automatically produce weaving models. The weaving models are derived into model integration transformations. To validate our approach, we present an experiment using metamodels with distinct size and complexity, which show the feasibility and scalability of our solution.

Engineering model transformations with transML

Model transformation is one of the pillars of model-driven engineering (MDE). The increasing complexity of systems and modelling languages has dramatically raised the complexity and size of model transformations as well. Even though many transformation languages and tools have been proposed in the last few years, most of them are directed to the implementation phase of transformation development. In this way, even though transformations should be built using sound engineering principles—just like any other kind of software—there is currently a lack of cohesive support for the other phases of the transformation development, like requirements, analysis, design and testing. In this paper, we propose a unified family of languages to cover the life cycle of transformation development enabling the engineering of transformations. Moreover, following an MDE approach, we provide tools to partially automate the progressive refinement of models between the different phases and the generation of code for several transformation implementation languages.     

Definition and validation of model transformations

With model transformations becoming more widely used, there is an increasing need for approaches focussing on a systematic development of model transformations. Although a number of approaches for specifying model transformations exist, none of them focusses on systematically validating model transformations with respect to termination and confluence. Termination and confluence ensure that a model transformation always produces a unique result. Also called functionality, these properties are important requirements for practical applications of model transformations. In this paper, we introduce our approach to model transformation. Using and extending results from the theory of graph transformation, we investigate termination and confluence properties of model transformations specified in our approach. We establish a set of criteria for termination and confluence to be checked at design time by static analysis of the transformation rules and the underlying metamodels. Moreover, the criteria are formulated in such a way that they require less experience with the theory of graph transformation. Our concepts are illustrated by a running example of a model tranformation from statecharts to the process algebra Communicating Sequential Processes.     

Coupling solvers with model transformations to generate explorable model sets

Software and Systems Modeling - Model transformation is an effective technique to produce target models from source models. Most transformation approaches focus on generating a single target model...     

Testing transformations for the linear mixed model

Transformation of the response of a linear model is a popular method in practice when attempting to satisfy the assumptions of the model. Environmental research routinely uses log-transformations due to the nature of the observed data. The choice of the transformation is often made based upon previous experience or on the comparison of models with different transformed responses. Often a transformation parameter is estimated when fitting a model to a set of data. However, in practice interpretability becomes an issue, as it is only desired to know if a particular transformation is appropriate. Thus, inference tools for a hypothesized value of the transformation, such as the log-transformation in environmental exposure models, have their merit. An examination of hypothesis tests of the transformation parameter in the general linear mixed model will be beneficial due to its practical applications, particularly for areas of environmental research. The effect of outliers on inference about the transformation parameter is also studied.     

Qualifying input test data for model transformations

Model transformation is a core mechanism for model-driven engineering (MDE). Writing complex model transformations is error-prone, and efficient testing techniques are required as for any complex program development. Testing a model transformation is typically performed by checking the results of the transformation applied to a set of input models. While it is fairly easy to provide some input models, it is difficult to qualify the relevance of these models for testing. In this paper, we propose a set of rules and a framework to assess the quality of given input models for testing a given transformation. Furthermore, the framework identifies missing model elements in input models and assists the user in improving these models.

Design pattern oriented development of model transformations

Model-driven engineering (MDE) is considered a well-established software development approach that uses abstraction to bridge the gap between the problem space and the software implementation. In MDE, many problems are solved using model transformation, which is a paradigm that manipulates high-level models to translate, evolve, or simulate them. However, the development of a model transformation for a specific problem is still a hard task. The main reason is the lack of a development process where transformations must be designed before implemented. Design patterns provide experiential reuse to software engineers when faced with recurring problems. Given their various contexts of application, model transformations may also benefit from design patterns. Although several studies have proposed design patterns for model transformation, there is still no accepted common language to express transformation patterns. Therefore, we propose a semi-formal way to describe model transformation design patterns that is independent from a specific transformation language and described in a practical way that is directly implementable by model engineers. This paper presents a catalog of 15 model transformation design patterns. We also demonstrate how it is possible to automatically generate excerpts of a model transformation in various languages given a design pattern. We conducted an initial survey to motivate the need for model transformation design patterns and a user study to validate the methodology we propose to solve problems as model transformations based on design patterns.     

The design of a language for model transformations

Model-driven development of software systems envisions transformations applied in various stages of the development process. Similarly, the use of domain-specific languages also necessitates transformations that map domain-specific constructs into the constructs of an underlying programming language. Thus, in these cases, the writing of transformation tools becomes a first-class activity of the software engineer. This paper introduces a language that was designed to support implementing highly efficient transformation programs that perform model-to-model or model-to-code translations. The language uses the concepts of graph transformations and metamodeling, and is supported by a suite of tools that allow the rapid prototyping and realization of transformation tools.     

Model transformations in simulation and planning: behaviorpreserving model simplifications

Reasoning tasks such as simulation and planning involve deriving behavior of a system from a model of the system. The information needed to solve such problems can be represented as model behavior pairs (MBPs). The problem can be stated as one or more incomplete MBPs. The problem-solving method can be expressed as a sequence of MBP completions and comparisons. A language for representing and manipulating models, behaviors, and MBPs is presented. It is independent of any specific modeling domain. An important class of model transformation operators is the behavior-preserving model transformation operators. Because they preserve behavior, they can be used to simplify a model without compromising its value for problem solving. This sort of operator can speed up computations significantly. It can be used either to select an appropriate sub-model for a specific problem or to decompose a problem into a sequence of subproblems. A behavior-preserving pruning operator is presented and shown to work in three modeling domains: discrete event simulation (DES), planning, and qualitative physics (QP). The significance of this work lies in the domain independence of the language and operators. It provides a representation midway between the computer-oriented concepts of programming languages (and knowledge representation schemes) and the problem oriented concepts of the real world. The benefits that can result from such a representation are easy mapping of problem-to-solution method, easy communication between solution methods (when more than one reasoning technique is required to solve a problem) and efficient solution of problems     

Efficient and scalable omniscient debugging for model transformations

This paper discusses a technique for supporting omniscient debugging for model transformations, which are used to define core operations on software and system models. Similar to software systems developed using general-purpose languages, model transformations are also subject to human error and may possess defects. Existing model-driven engineering tools provide stepwise execution to aid developers in locating and removing defects. In this paper, we describe our investigation into a technique and associated algorithms that support omniscient debugging features for model transformations. Omniscient debugging enables enhanced navigation and exploration features during a debugging session beyond those possible in a strictly stepwise execution environment. Finally, the execution time performance is comparatively evaluated against stepwise execution, and the scalability (in terms of memory usage) is empirically investigated.     

Testing models and model transformations using classifying terms

This paper proposes the use of equivalence partitioning techniques for testing models and model transformations. In particular, we introduce the concept of classifying terms, which are general OCL terms on a class model enriched with OCL constraints. Classifying terms permit defining equivalence classes, in particular for partitioning the source and target model spaces of the transformation, defining for each class a set of equivalent models with regard to the transformation. Using these classes, a model validator tool is able to automatically construct object models for each class, which constitute relevant test cases for the transformation. We show how this approach of guiding the construction of test cases in an orderly, systematic and efficient manner can be effectively used in combination with Tracts for testing both directional and bidirectional model transformations and for analyzing their behavior.     

Assessing and improving quality of QVTo model transformations

We investigate quality improvement in QVT operational mappings (QVTo) model transformations, one of the languages defined in the OMG standard on model-to-model transformations. Two research questions are addressed. First, how can we assess quality of QVTo model transformations? Second, how can we develop higher-quality QVTo transformations? To address the first question, we utilize a bottom–up approach, starting with a broad exploratory study including QVTo expert interviews, a review of existing material, and introspection. We then formalize QVTo transformation quality into a QVTo quality model. The quality model is validated through a survey of a broader group of QVTo developers. We find that although many quality properties recognized as important for QVTo do have counterparts in general purpose languages, a number of them are specific to QVTo or model transformation languages. To address the second research question, we leverage the quality model to identify developer support tooling for QVTo. We then implemented and evaluated one of the tools, namely a code test coverage tool. In designing the tool, code coverage criteria for QVTo model transformations are also identified. The primary contributions of this paper are a QVTo quality model relevant to QVTo practitioners and an open-source code coverage tool already usable by QVTo transformation developers. Secondary contributions are a bottom–up approach to building a quality model, a validation approach leveraging developer perceptions to evaluate quality properties, code test coverage criteria for QVTo, and numerous directions for future research and tooling related to QVTo quality.     

Model replication: transformations to address model scalability

In model‐driven engineering, it is often desirable to evaluate different design alternatives as they relate to scalability issues of the modeled system. A typical approach to address scalability is model replication, which starts by creating base models that capture the key entities as model elements and their relationships as model connections. A collection of base models can be adorned with necessary information to characterize a specific scalability concern as it relates to how the base modeling elements are replicated and connected together. In current modeling practice, such a model replication is usually accomplished by scaling the base model manually. This is a time‐consuming process that represents a source of error, especially when there are deep interactions between model components. As an alternative to the manual process, this paper presents the idea of automated model replication through a model transformation process that expands the number of elements from the base model and makes the correct connections among the generated modeling elements. The paper motivates the need for model replication through case studies taken from models supporting different domains. Copyright © 2008 John Wiley & Sons, Ltd.     

Modularization of model transformations through a phasing mechanism

In recent years a great effort has been devoted to understanding the nature of model transformations. As a result, several mechanisms to improve model transformation languages have been proposed. Phasing has been mentioned in some works as a rule scheduling or organization mechanism, but without any detail. In this paper, we present a phasing mechanism in the context of rule-based transformation languages. We explain the structure and the behavior of the mechanism, and how it can be integrated in a language. We also analyze how the mechanism promotes modularity, internal transformation composition and helps to solve usual transformation problems. Besides, we show several examples of application to illustrate the usefulness of the mechanism.     

Correct-by-construction synthesis of model transformations using transformation patterns

Model transformations are an essential part of model-based development approaches, such as Model-driven Architecture (MDA) and Model-driven Development (MDD). Model transformations are used to refine and abstract models, to re-express models in a new modelling language, and to analyse, refactor, compare and improve models. Therefore, the correctness of model transformations is critically important for successful application of model-based development: software developers should be able to rely upon the correct processing of their models by transformations in the same way that they rely upon compilers to produce correct executable versions of their programs. In this paper, we address this problem by defining standard structures for model transformation specifications and implementations, which serve as patterns and strategies for constructing a wide range of model transformations. These are incorporated into a tool-supported process which automatically synthesises implementations of model transformations from their specifications, these implementations are correct-by-construction with respect to their specifications.     

Model-driven engineering city spaces via bidirectional model transformations

Software and Systems Modeling - Engineering cyber-physical systems inhabiting contemporary urban spatial environments demands software engineering facilities to support design and operation. Tools...