Model-driven analysis and synthesis of textual concrete syntax

Meta-modeling is raising more and more interest in the field of language engineering. While this approach is now well understood for defining abstract syntaxes, formally defining textual concrete syntaxes with meta-models is still a challenge. Textual concrete syntaxes are traditionally expressed with rules, conforming to EBNF-like grammars, which can be processed by compiler compilers to generate parsers. Unfortunately, these generated parsers produce concrete syntax trees, leaving a gap with the abstract syntax defined by meta-models, and further ad hoc hand-coding is required. In this paper we propose a new kind of specification for concrete syntaxes, which takes advantage of meta-models to generate fully operational tools (such as parsers or text generators). The principle is to map abstract syntaxes to textual concrete syntaxes via bidirectional mapping-models with support for both model-to-text, and text-to-model transformations.

MontiCore: a framework for compositional development of domain specific languages

Domain specific languages (DSLs) are increasingly used today. Coping with complex language definitions, evolving them in a structured way, and ensuring their error freeness are the main challenges of DSL design and implementation. The use of modular language definitions and composition operators are therefore inevitable in the independent development of language components. In this article, we discuss these arising issues by describing a framework for the compositional development of textual DSLs and their supporting tools. We use a redundance-free definition of a readable concrete syntax and a comprehensible abstract syntax as both representations significantly overlap in their structure. For enhancing the usability of the abstract syntax, we added concepts like associations and inheritance to a grammar-based definition in order to build up arbitrary graphs (as known from metamodeling). Two modularity concepts, grammar inheritance and embedding, are discussed. They permit compositional language definition and thus simplify the extension of languages based on already existing ones. We demonstrate that compositional engineering of new languages is a useful concept when project-individual DSLs with appropriate tool support are defined.     

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.     

Correctly defined concrete syntax

Due to their complexity, the syntax of modern modeling languages is preferably defined in two steps. The abstract syntax identifies all modeling concepts whereas the concrete syntax should clarify how these concepts are rendered by graphical and/or textual elements. While the abstract syntax is often defined in form of a metamodel, there does not exist such standard format yet for concrete syntax definitions. The diversity of definition formats—ranging from EBNF grammars to informal text—is becoming a major obstacle for advances in modeling language engineering, including the automatic generation of editors. In this paper, we propose a uniform format for concrete syntax definitions. Our approach captures both textual and graphical model representations and even allows to assign more than one rendering to the same modeling concept. Consequently, following our approach, a model can have multiple, fully equivalent representations, but—in order to avoid ambiguities when reading a model representation—two different models should always have distinguishable representations. We call a syntax definition correct, if all well-formed models are represented in a non-ambiguous way. As the main contribution of this paper, we present a rigorous analysis technique to check the correctness of concrete syntax definitions.

Synchronization of abstract and concrete syntax in domain-specific modeling languages

Modern domain-specific modeling (DSM) frameworks provide refined techniques for developing new languages based on the clear separation of conceptual elements of the language (called abstract syntax) and their graphical visual representation (called concrete syntax). This separation is usually achieved by recording traceability information between the abstract and concrete syntax using mapping models. However, state-of-the-art DSM frameworks impose severe restrictions on traceability links between elements of the abstract syntax and the concrete syntax. In the current paper, we propose a mapping model which allows to define arbitrarily complex mappings between elements of the abstract and concrete syntax. Moreover, we demonstrate how live model transformations can complement mapping models in providing bidirectional synchronization and implicit traceability between models of the abstract and the concrete syntax. In addition, we introduce a novel architecture for DSM environments which enables these concepts, and provide an overview of the tool support.     

Domain-specific language modelling with UML profiles by decoupling abstract and concrete syntaxes

UML profiling presents some acknowledged deficiencies, among which the lack of expressiveness of the profiled notations, together with the high coupling between abstract and concrete syntaxes outstand. These deficiencies may cause distress among UML-profile modellers, who are often forced to extend from unsuitable metaclasses for mere notational reasons, or even to model domain-specific languages from scratch just to avoid the UML-profiling limitations.In order to palliate this situation, this article presents an extension of the UML profile metamodel to support arbitrarily-complex notational extensions by decoupling the UML abstract and concrete syntax. Instead of defining yet another metamodel for UML-notational profiling, notational extensions are modelled with DI, i.e., the UML notation metamodel for diagram interchange, keeping in this way the extension within the standard. Profiled UML notations are rendered with DI by defining the graphical properties involved, the domain-specific constraints applied to DI, and the rendering routines associated. Decoupling abstract and concrete syntax in UML profiles increases the notation expressiveness while decreasing the abstract-syntax complexity.     

A domain-specific language for context modeling in context-aware systems

Context-awareness refers to systems that can both sense and react based on their environment. One of the main difficulties that developers of context-aware systems must tackle is how to manage the needed context information. In this paper we present MLContext, a textual Domain-Specific Language (DSL) which is specially tailored for modeling context information. It has been implemented by applying Model-Driven Development (MDD) techniques to automatically generate software artifacts from context models. The MLContext abstract syntax has been defined as a metamodel, and model-to text transformations have been written to generate the desired software artifacts. The concrete syntax has been defined with the EMFText tool, which generates an editor and model injector.     

Reusing metamodels and notation with Diagram Definition

It is increasingly common for language specifications to describe visual forms (concrete syntax) separately from underlying concepts (abstract syntax). This is typically to enable interchange of visual information between graphical modeling tools, such as positions of nodes and routings of lines. Often overlooked is that separation of visual forms and abstract concepts enables languages to define multiple visual forms for the same underlying concepts and for the same visual form to be used for similar underlying concepts in different languages (many-to-many relationships between concrete and abstract syntax). Visual forms can be adapted to communities using different notations for the same concepts and can be used to integrate communities using the same notation for similar concepts. Models of concrete syntax have been available for some time, but are rarely used to capture these many-to-many relationships with abstract syntax. This paper shows how to model these relationships using concrete graphical syntax expressed in the Diagram Definition standard, examining cases drawn from the Unified Modeling Language and the Business Process Model and Notation. This gives definers of graphical languages a way to specify visual forms for multiple communities.     

Language design for program manipulation

The design of procedural and object-oriented programming languages is considered with respect to how easily programs written in those languages can be formally manipulated. Current procedural languages such as Pascal, Modula-2 and Ada; generally support such program manipulations, except for some annoying anomalies and special cases. Three main areas of language design are identified as being of concern from a manipulation viewpoint: the interface between concrete and abstract syntax; the relationship between the abstract syntax and static semantics naming, scoping and typing; and the ability to express basic transformations (folding and unfolding). Design principles are suggested so that the problems identified for current languages can be avoided in the future     

Contrasting dedicated model transformation languages versus general purpose languages: a historical perspective on ATL versus Java based on complexity and size

Model transformations are among the key concepts of model-driven engineering (MDE), and dedicated model transformation languages (MTLs) emerged with the popularity of the MDE pssaradigm about 15 to 20 years ago. MTLs claim to increase the ease of development of model transformations by abstracting from recurring transformation aspects and hiding complex semantics behind a simple and intuitive syntax. Nonetheless, MTLs are rarely adopted in practice, there is still no empirical evidence for the claim of easier development, and the argument of abstraction deserves a fresh look in the light of modern general purpose languages (GPLs) which have undergone a significant evolution in the last two decades. In this paper, we report about a study in which we compare the complexity and size of model transformations written in three different languages, namely (i) the Atlas Transformation Language (ATL), (ii) Java SE5 (2004–2009), and (iii) Java SE14 (2020); the Java transformations are derived from an ATL specification using a translation schema we developed for our study. In a nutshell, we found that some of the new features in Java SE14 compared to Java SE5 help to significantly reduce the complexity of transformations written in Java by as much as 45%. At the same time, however, the relative amount of complexity that stems from aspects that ATL can hide from the developer, which is about 40% of the total complexity, stays about the same. Furthermore we discovered that while transformation code in Java SE14 requires up to 25% less lines of code, the number of words written in both versions stays about the same. And while the written number of words stays about the same their distribution throughout the code changes significantly. Based on these results, we discuss the concrete advancements in newer Java versions. We also discuss to which extent new language advancements justify writing transformations in a general purpose language rather than a dedicated transformation language. We further indicate potential avenues for future research on the comparison of MTLs and GPLs in a model transformation context.

     

Grammar-based model transformations: Definition,execution, and quality properties

Model transformation is a key concept in model-driven software engineering. The definition of model transformations is usually based on meta-models describing the abstract syntax of languages. While meta-models are thereby able to abstract from superfluous details of concrete syntax, they often loose structural information inherent in languages, like information on model elements always occurring together in particular shapes. As a consequence, model transformations cannot naturally re-use language structures, thus leading to unnecessary complexity in their development as well as in quality assurance.In this paper, we propose a new approach to model transformation development which allows to simplify the developed transformations and improve their quality via the exploitation of the languages׳ structures. The approach is based on context-free graph grammars and transformations defined by pairing productions of source and target grammars. We show that such transformations have important properties: they terminate and are sound, complete, and deterministic.     

数字权利描述语言互操作研究

为实现数字作品的共享,提出了实现不同的权利描述语言的互操作方法.根据主要的几种权利描述语言规范的特点,提出了权利描述语言的数据模型、实体元素的语义、语法特性等的映射机制.研究了权利描述语言规范间的互操作策略,介绍了权利描述语言间的互操作方法,实现了权利描述语言规范互操作的转换工具,实验结果表明了该方法的可行性.     

OSI／MMS系统中ASN.1编／解码器的设计与实现

ＡＳＮ．１是一种标准的抽象语法定义描述语言，它提供了定义复杂数据类型以及确定这些数据类型值的方法，许多ＯＳＩ应用协议标准都采用ＡＳＮ．１作为数据结构定义描述工具，尤其用来定义各各应用协议数据单元的结构。本文首先介绍ＡＳＮ．１数据类型和基本编码规则，接着详细讨论ＭＭＳ通信系统中ＡＳＮ．１编／解码器的设计与实现，此编／解码器用于ＭＭＳ协议数据单元的ＡＳＮ．１抽象语法和传送语法之间的转换，以实现ＭＭＳ在     

Formal verification of static software models in MDE: A systematic review

ContextModel-driven Engineering (MDE) promotes the utilization of models as primary artifacts in all software engineering activities. Therefore, mechanisms to ensure model correctness become crucial, specially when applying MDE to the development of software, where software is the result of a chain of (semi)automatic model transformations that refine initial abstract models to lower level ones from which the final code is eventually generated. Clearly, in this context, an error in the model/s is propagated to the code endangering the soundness of the resulting software. Formal verification of software models is a promising approach that advocates the employment of formal methods to achieve model correctness, and it has received a considerable amount of attention in the last few years.ObjectiveThe objective of this paper is to analyze the state of the art in the field of formal verification of models, restricting the analysis to those approaches applied over static software models complemented or not with constraints expressed in textual languages, typically the Object Constraint Language (OCL).MethodWe have conducted a Systematic Literature Review (SLR) of the published works in this field, describing their main characteristics.ResultsThe study is based on a set of 48 resources that have been grouped in 18 different approaches according to their affinity. For each of them we have analyzed, among other issues, the formalism used, the support given to OCL, the correctness properties addressed or the feedback yielded by the verification process.ConclusionsOne of the most important conclusions obtained is that current model verification approaches are strongly influenced by the support given to OCL. Another important finding is that in general, current verification tools present important flaws like the lack of integration into the model designer tool chain or the lack of efficiency when verifying large, real-life models.     

Graph transformations and software engineering: Success stories and lost chances

Textual as well as visual and diagrammatic notations are essential in software engineering, and are used in many different contexts. Chomsky grammars are the key tool to handle textual notations, and find many applications for textual languages. Visual and diagrammatic languages add spatial dimensions that reduce the applicability of textual grammars and call for new tools.Graph transformation systems have been studied for over 40 years and are a powerful tool to deal with syntax, semantics and transformation of diagrammatic notations. The enormous importance of visual and diagrammatic languages and the strong support that graph transformation provide to the manipulation of diagrammatic notations would suggest a big success of graph transformation in software engineering.Graph transformation systems find their application both as language generating devices and specification means for system evolution, and thus can have many applications in software engineering. In this paper we discuss the main features of graph transformation and how they can help software engineers. We look back to the many attempts to use graph transformations in software engineering in the last 15 years, identify some success stories, and discuss to what extent graph transformation succeeded, when they have not succeeded yet, what are the main causes of failures, and how they can help software engineering in the next 15 years.     

Dual syntax for XML languages

XML is successful as a machine processable data interchange format, but it is often too verbose for human use. For this reason, many XML languages permit an alternative more legible non-XML syntax. XSLT stylesheets are often used to convert from the XML syntax to the alternative syntax; however, such transformations are not reversible since no general tool exists to automatically parse the alternative syntax back into XML.

We present XSugar, which makes it possible to manage dual syntax for XML languages. An XSugar specification is built around a context-free grammar that unifies the two syntaxes of a language. Given such a specification, the XSugar tool can translate from alternative syntax to XML and vice versa. Moreover, the tool statically checks that the transformations are reversible and that all XML documents generated from the alternative syntax are valid according to a given XML schema.     

The Specification of Assemblers

The problem of applying formal techniques of program specification and verification to large complex programs is considered. It is argued that a practical solution requires a variety of techniques, including both procedural and nonprocedural specifications, hierarchical program organization, and the use of program transformations. In particular, a case is made for flexible problem-oriented choice of specification techniques and languages. These ideas are expanded by specifying a load-and-go assembler in three parts: a transduction grammar describing the correspondence between concrete and abstract syntax for assembly language programs; a set of transformations of the abstract form; and a nonconstructive axiomatic specification of the result of core assembly and loading of transformed abstract programs.     

Alliance of model-driven engineering with a proof-based formal approach

Model-driven engineering (MDE) promotes the use of models throughout the software development cycle in order to increase abstraction and reduce software complexity. It favors the definition of domain-specific modeling languages (DSMLs) thanks to frameworks dedicated to meta-modeling and code generation like EMF (Eclipse Modeling Framework). The standard semantics of meta-models allows interoperability between tools such as language analysers (e.g., XText), code generators (e.g., Acceleo), and also model transformation tools (e.g., ATL). However, a major limitation of MDE is the lack of formal reasoning tools allowing to ensure the correctness of models. Indeed, most of the verification activities offered by MDE tools are based on the verification of OCL constraints on instances of meta-models. However, these constraints mainly deal with structural properties of the model and often miss out its behavioral semantics. In this work, we propose to bridge the gap between MDE and the rigorous world of formal methods in order to guarantee the correctness of both structural and behavioral properties of the model. Our approach translates EMF meta-models into an equivalent formal B specification and then injects models into this specification. The equivalence between the resulting B specification and the original EMF model is kept by proven design steps leading to a rigorous MDE technique. The AtelierB prover is used to guarantee the correctness of the model’s behavior with respect to its invariant properties, and the ProB model-checker is used to animate underlying execution scenarios which are translated back to the initial EMF model. Besides the use of these automatic reasoning tools in MDE, proved B refinements are also investigated in this paper in order to gradually translate abstract EMF models to concrete models which can then be automatically compiled into a programming language.

     

VMTL: a language for end-user model transformation

Model transformation is a key enabling technology of Model-Driven Engineering (MDE). Existing model transformation languages are shaped by and for MDE practitioners—a user group with needs and capabilities which are not necessarily characteristic of modelers in general. Consequently, these languages are largely ill-equipped for adoption by end-user modelers in areas such as requirements engineering, business process management, or enterprise architecture. We aim to introduce a model transformation language addressing the skills and requirements of end-user modelers. With this contribution, we hope to broaden the application scope of model transformation and MDE technology in general. We discuss the profile of end-user modelers and propose a set of design guidelines for model transformation languages addressing them. We then introduce Visual Model Transformation Language (VMTL) following these guidelines. VMTL draws on our previous work on the usability-oriented Visual Model Query Language. We implement VMTL using the Henshin model transformation engine, and empirically investigate its learnability via two user experiments and a think-aloud protocol analysis. Our experiments, although conducted on computer science students exhibiting only some of the characteristics of end-user modelers, show that VMTL compares favorably in terms of learnability with two state-of the-art model transformation languages: Epsilon and Henshin. Our think-aloud protocol analysis confirms many of the design decisions adopted for VMTL, while also indicating possible improvements.     

Defining the abstract syntax of visual languages with advanced graph grammars—A case study based on behavior trees

Diagrammatic visual languages can increase the ability of engineers to model and understand complex systems. However, to effectively use visual models, the syntax and semantics of these languages should be defined precisely. Since most diagrammatic visual models that are currently used to specify systems can be described as (directed) typed graphs, graph grammars have been identified as a suitable formalism to describe the abstract syntax of visual modeling languages. In this article, we investigate how advanced graph-transformation techniques, such as conditional, structure-generic and type-generic graph-transformation rules, can help to improve and simplify the specification of the abstract syntax of a visual modeling language. To demonstrate the practicability of an approach that unifies these advanced graph-transformation techniques, we define the abstract syntax of behavior trees (BTs), a graphical specification language for functional requirements. Additionally, we provide a translational semantics of BTs by formalizing a translation scheme to the input language of the SAL model checking tool for each of the graph-transformation rules.