Consistency of model transformation contracts

Model-driven development is a generative software development process with increasing relevance both in industry and academia. Model transformations are the generative components in a model-driven development process. As such, their analysis is an important task. We have been developing a technique to specify, validate and implement model transformations. Our technique is based on the concept of transformation contracts, a specification that relates two modeling languages and declares properties that must be fulfilled in such a relation. Since a transformation contract is a model, the verification and validation of a transformation contract use the same techniques that are used to verify and validate any given model. This paper describes our technique, discusses consistency of model transformations and reports on its application to a non-trivial model transformation from access control models to Java security.     

Semantic model-driven architecting of service-based software systems

Model-driven development is a software development framework that emphasises model-based abstraction and automated code generation. Service-based software architectures benefit in particular from semantic, ontology-based modelling. We present ontology-based transformation and reasoning techniques for layered semantic service architecture modelling. Integrated ontological layers support abstract domain modelling, architectural design, and interoperability aspects. Ontologies are beneficial due to their potential to formally define models, to allow reasoning about semantic models, and to automate transformations at all layers. Ontologies are suitable in particular for the Web Services platform due to their ubiquity within the Semantic Web and their application to support semantic Web services.     

From types to type requirements: genericity for model-driven engineering

Model-driven engineering (MDE) is a software engineering paradigm that proposes an active use of models during the development process. This paradigm is inherently type-centric, in the sense that models and their manipulation are defined over the types of specific meta-models. This fact hinders the reuse of existing MDE artefacts with other meta-models in new contexts, even if all these meta-models share common characteristics. To increase the reuse opportunities of MDE artefacts, we propose a paradigm shift from type-centric to requirement-centric specifications by bringing genericity into models, meta-models and model management operations. For this purpose, we introduce so-called concepts gathering structural and behavioural requirements for models and meta-models. In this way, model management operations are defined over concepts, enabling the application of the operations to any meta-model satisfying the requirements imposed by the concept. Model templates rely on concepts to define suitable interfaces, hence enabling the definition of reusable model components. Finally, similar to mixin layers, templates can be defined at the meta-model level as well, to define languages in a modular way, as well as layers of functionality to be plugged-in into other meta-models. These ideas have been implemented in MetaDepth, a multi-level meta-modelling tool that integrates action languages from the Epsilon family for model management and code generation.     

Formalised EMFTVM bytecode language for sound verification of model transformations

Model-driven engineering is an effective approach for addressing the full life cycle of software development. Model transformation is widely acknowledged as one of its central ingredients. With the increasing complexity of model transformations, it is urgent to develop verification tools that prevent incorrect transformations from generating faulty models. However, the development of sound verification tools is a non-trivial task, due to unimplementable or erroneous execution semantics encoded for the target model transformation language. In this work, we develop a formalisation for the EMFTVM bytecode language by using the Boogie intermediate verification language. It ensures the model transformation language has an implementable execution semantics by reliably prototyping the implementation of the model transformation language. It also ensures the absence of erroneous execution semantics encoded for the target model transformation language by using a translation validation approach.     

Lifting transformational models of product lines: a case study

Model driven engineering (MDE) of software product lines (SPLs) merges two increasing important paradigms that synthesize programs by transformation. MDE creates programs by transforming models, and SPLs elaborate programs by applying transformations called features. In this paper, we present the design and implementation of a transformational model of a product line of scalar vector graphics and JavaScript applications. We explain how we simplified our implementation by lifting selected features and their compositions from our original product line (whose implementations were complex) to features and their compositions of another product line (whose specifications were simple). We used operators to map higher-level features and their compositions to their lower-level counterparts. Doing so exposed commuting relationships among feature compositions in both product lines that helped validate our model and implementation.     

Testing operational transformations in model-driven engineering

Model-driven development is gaining importance in software engineering practice. This increasing usage asks for a new generation of testing tools to verify correctness and suitability of model transformations. This paper presents a novel approach to unit testing QVT operational (QVTO) transformations, which overcomes limitations of currently available tools. Our proposal, called MANTra (Model trANsformation Testing), allows software developers to design test cases directly within the QVTO language and verify them without moving from the transformation environment. MANTra is also available as an eclipse feature that can be easily integrated into established development practice.     

Model transformations in the UPES/UPSoC development process for embedded systems

Model-based development (MBD) aims at combining modeling languages with model transformers and code generators. Modeling languages, like profiles of the Unified Modeling Language (UML), are increasingly being adopted for specific domains of interest to alleviate the complexity of platforms and express domain concepts effectively. Moreover, system development processes based on automatic model transformations are widely required to improve the productivity and quality of the developed systems. In this paper, we show how MBD principles and automatic model transformations provide the basis for the unified process for embedded systems (UPES) development process and its unified process for system-on-chip (SoC) (UPSoC) subprocess. They have been defined to foster in a systematic and seamless manner a model-based design methodology based on the UML2 and UML profiles for the C/SystemC programming languages, which we developed to improve the current industrial system design flow in the embedded systems and system-on-chip area. This work is supported in part by the project Model-driven methodologies and techniques for embedded systems design and analysis based on UML, Abstract State Machines, and SystemC at STMicroelectronics, AST R&I of Agrate Brianza (MI), Italy.     

Formal requirements modelling with executable use cases and coloured Petri nets

This paper presents executable use cases (EUCs), which constitute a model-based approach to requirements engineering. EUCs may be used as a supplement to model-driven development (MDD) and can describe and link user-level requirements and more technical software specifications. In MDD, user-level requirements are not always explicitly described, since usually it is sufficient that one provides a specification, or platform-independent model, of the software that is to be developed. Therefore, a combination of EUCs and MDD may have potential to cover the path from user-level requirements via specifications to implementations of computer-based systems.     

An MDE-based method for bridging different design notations

Different communities have developed plenty of design notations for software engineering in support of practical (via UML) and rigorous (via formal methods) approaches. Hence the problem of bridging these notations rises. Model-driven engineering (MDE) is a new paradigm in software engineering, which treats models and model transformations as first class citizens. Furthermore, it is seen as a promising method for bridging heterogeneous platforms. In this paper, we provide an MDE-based approach to build bridges between informal, semi-formal and formal notations: Firstly, different notations are viewed as different domain specification languages (DSLs) and introduced into MDE, especially into the ATLAS Model Management Architecture (AMMA) platform, by metamodeling. Then, ATL transformation rules are built for semantics mapping. At last, TCS-based model-to-text syntax rules are developed, allowing one to map models to programs. Consequently, different design notations in both graphical style and grammatical style are bridged. A case study of bridging OMG SysML™ to LOTOS is also illustrated showing the validity and practicability of our approach.     

A model-adaptive evolutionary algorithm for optimization

Many applications in engineering and science rely on the optimization of computationally expensive functions. A successful approach in such scenarios is to couple an evolutionary algorithm with a mathematical model which replaces the expensive function. However, models introduce several difficulties, such as their inherent inaccuracy, and the difficulty of matching a model to a particular problem. To address these issues, this paper proposes a model-based evolutionary algorithm with two main implementations: (a) it combats model inaccuracy with a tailored trust-region approach to manage the model during the search, and to ensure convergence to an optimum of the true expensive function, and (b) during the search it continuously selects an optimal model type out of a set of candidate models, resulting in a model-adaptive optimization search. Extensive performance analysis shows the efficacy of the proposed algorithm.     

Leveraging UML Profiles to Generate Plugins From Visual Model Transformations

Model transformation is a fundamental technology in the MDA. Therefore, model transformations should be treated as first class entities, that is, models. One could use the metamodel of SDM, a graph based object transformation language, as the metamodel of such transformation models. However, there are two problems associated with this. First, SDM has a non-standardized metamodel, meaning a specific tool (Fujaba) would be needed to write transformation specifications. Secondly, due to assumptions of the code generator, the transformations could only be deployed on the Fujaba tool itself. In this paper, we describe how these issues have been overcome through the development of a template based code generator that translates instances of a UML profile for SDM to complete model transformation code that complies to the JMI standard. We have validated this approach by specifying a simple visual refactoring in one UML tool and deploying the generated plugin on another UML tool.     

A relational approach to defining and implementing transformations between metamodels

The Model-Driven Architecture initiative of the OMG promotes the idea of transformations in the context of mapping from platform independent to platform specific models. Additionally, the popularity of XML and the wide spread use of XSLT has raised the profile of model transformation as an important technique for computing. In fact, computing may well be moving to a new paradigm in which models are considered first class entities and transformations between them are a major function performed on those models. This paper proposes an approach to defining and implementing model transformations which uses metamodelling patterns to capture the essence of mathematical relations. It shows how these patterns can be used to define the relationship between two different metamodels. A goal of the approach is to enable complete specifications from which tools can be generated. The paper describes implementations of the examples, which have been partially generated from the definitions using a tool generation tool. A number of issues emerge which need to be solved in order to achieve the stated goal; these are discussed.     

MDE for SoC design

We employ the principles of model-driven engineering to assist the design of system-on-chip (SoC) architectures. As a concrete example, we look at the MICAS architecture, for which we propose a graphical specification language, defined via metamodeling techniques, that models the architecture at different abstraction levels. Model transformations are defined to support the refinement of MICAS specification towards implementation. In addition, several libraries are put in place, to enable reuse and automation throughout the design process. Tool support for editing the specifications, enforcing their consistency, and for running the transformations is provided via the Coral modeling framework. The approach shows that model-driven engineering can be seen as an enabler in providing computer-aided software engineering (CASE) tool support and automation for the development of SoC architectures.     

Applying CIM-to-PIM model transformations for the service-oriented development of information systems

Context

Model-driven approaches deal with the provision of models, transformations between them and code generators to address software development. This approach has the advantage of defining a conceptual structure, where the models used by business managers and analysts can be mapped into more detailed models used by software developers. This alignment between high-level business specifications and the lower-level information technologies (ITs) models is crucial to the field of service-oriented development, where meaningful business services and process specifications are those relevant to real business scenarios.

Objective

This paper presents a model-driven approach which, starting from high-level computational-independent business models (CIMs) - the business view - sets out guidelines for obtaining lower-level platform-independent behavioural models (PIMs) - the information system view. A key advantage of our approach is the use of real high-level business models, not just requirements models, which, by means of model transformations, helps software developers to make the most of the business knowledge for specifying and developing business services.

Method

This proposal is framed in a method for service-oriented development of information systems whose main characteristic is the use of services as first-class objects. The method follows an MDA-based approach, proposing a set of models at different levels of abstraction and model transformations to connect them.

Results

The paper present the complete set of CIM and PIM metamodels and the specification of the mappings between them, which clear advantage is the support for the alignment between high-level business view and ITs. The proposed model-driven process is being implemented in an MDA tool. A first prototype has been used to develop a travel agency case study that illustrates the proposal.

Conclusion

This study shows how a model-driven approach helps to solve the alignment problem between the business view and the information system view that arises when adopting service-oriented approaches for software development.     

Model-checking dense-time Duration Calculus

Since the seminal work of Zhou Chaochen, M. R. Hansen, and P. Sestoft on decidability of dense-time Duration Calculus [ZHS93] it is well known that decidable fragments of Duration Calculus can only be obtained through withdrawal of much of the interesting vocabulary of this logic. While this was formerly taken as an indication that key-press verification of implementations with respect to elaborate Duration Calculus specifications were also impossible, we show that the model property is well decidable for realistic designs which feature natural constraints on their switching dynamics.The key issue is that the classical undecidability results rely on a notion of validity of a formula that refers to a class of models which is considerably richer than the possible behaviours of actual embedded real-time systems: that of finitely variable trajectories. By analysing two suitably sparser model classes we obtain model-checking procedures for rich subsets of Duration Calculus. Together with undecidability results also obtained, this sheds light upon the exact borderline between decidability and undecidability of Duration Calculi and related logics.Received June 1999Accepted in revised form September 2003 by M. R. Hansen and C. B. Jones     

Extracting models from source code in software modernization

Model-driven software modernization is a discipline in which model-driven development (MDD) techniques are used in the modernization of legacy systems. When existing software artifacts are evolved, they must be transformed into models to apply MDD techniques such as model transformations. Since most modernization scenarios (e.g., application migration) involve dealing with code in general-purpose programming languages (GPL), the extraction of models from GPL code is an essential task in a model-based modernization process. This activity could be performed by tools to bridge grammarware and MDD technical spaces, which is normally carried out by dedicated parsers. Grammar-to-Model Transformation Language (Gra2MoL) is a domain-specific language (DSL) tailored to the extraction of models from GPL code. This DSL is actually a text-to-model transformation language which can be applied to any code conforming to a grammar. Gra2MoL aims to reduce the effort needed to implement grammarware-MDD bridges, since building dedicated parsers is a complex and time-consuming task. Like ATL and RubyTL languages, Gra2MoL incorporates the binding concept needed to write mappings between grammar elements and metamodel elements in a simple declarative style. The language also provides a powerful query language which eases the retrieval of scattered information in syntax trees. Moreover, it incorporates extensibility and grammar reuse mechanisms. This paper describes Gra2MoL in detail and includes a case study based on the application of the language in the extraction of models from Delphi code.     

Comparative Evaluation of Model Transformation Specification Approaches

Model transformations have become a key element of model-driven software development, being used to transform platform-independent models to platform-specific models, to improve model quality, to introduce design patterns and refactorings, and to map models from one language to another. A large number of model transformation notations and tools exist. However, there are no guidelines on how to select appropriate notations for particular model transformation tasks, and no comprehensive comparisons of the relative merits of particular approaches. In this paper we provide a unified semantic treatment of model transformations, and show how correctness properties of model transformations can be defined using this semantics. We evaluate several approaches which have been developed for model transformation specification, with respect to their expressivity, complexity and support for verification, and make recommendations for resolving the outstanding problems concerning model transformation specification.     

Refinement-based Validation of Event-B Specifications

The validation of formal specifications is a challenging task. It is one of the factors that impede the penetration of formal methods into the common practices of software development. This paper discusses the issue of validating formal models by executing them in the context of Event-B. The most important problem lies in the non-determinism which often prevents purely automatic tools to execute models. In this paper, we first present and discuss the techniques we have created to allow the execution of models at all levels of abstraction. These techniques rely on users to overcome the barriers resulting from non-deterministic features by either modifying the model or providing ad hoc implementations. Then, we present our main contribution, the formal definition of the notion of fidelity, that guarantees that all the observable behaviors of the executable models are indeed specified by the original (non-deterministic) models. The notion of fidelity can be expressed in terms of proof obligations.     

Tool Support for Refinement of Non-functional Specifications

Model driven architecture (MDA) views application development as a continuous transformation of models of the target system. We propose a methodology which extends this view to non-functional properties. In previous publications we have shown how we can use so-called context models to make the specification of non-functional measurements independent of their application in concrete system specifications. We have also shown how this allows us to distinguish two roles in the development process: the measurement designer and the application designer. In this paper we use the notion of context models to allow the measurement designer to provide measurement definitions at different levels of abstraction. A measurement in our terminology is a non-functional dimension that can be constrained to describe a non-functional property. Requiring the measurement designer to define transformations between context models, and applying them to measurement definitions, enables us to provide tool support for refinement of non-functional constraints to the application designer. The paper presents the concepts for such tool support as well as a prototype implementation.     

TT-BIP: using correct-by-design BIP approach for modelling real-time system with time-triggered paradigm

In order to combine advantages of real-time operating systems implementing the time-triggered (TT) execution model and model-based design frameworks, we aim at proposing a correct-by-design methodology that derives correct TT implementations from high-level models. This methodology consists of two main steps: (1) transforming the high-level model into an intermediate model which respects the TT communication principles and where all communications between components are simple send/receive interactions, and (2) transforming the obtained intermediate model into the programming language of the target platform. In this paper, we focus on the presentation of the transformational methodology of the first step of this design flow. This methodology produces a correct-by-construction TT model by starting from a high-level model of the application software in behaviour, interaction, priority (BIP). BIP is a component-based framework with formal semantics that rely on multiparty interactions for synchronizing components. Commonly in TT implementations, tasks interact with each other through a communication medium. Our methodology transforms, depending on a user-defined task mapping, high-level BIP models where communication between components is strongly synchronized, into TT model that integrates a communication medium. Thus, only inter-task communications and components participating in such interactions are concerned by the transformation process. We also provide correctness proofs of the transformation and apply it on an industrial case study.