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About this book

This book constitutes the thoroughly refereed post-proceedings of the Third International Conference on Software Language Engineering, SLE 2010, held in Eindhoven, The Netherlands, in October 2010. The 24 papers presented were carefully reviewed and selected from 79 submissions. The book also contains the abstracts of two invited talks. The papers are grouped in topical sections on grammarware, metamodeling, evolution, programming, and domain-specific languages. The short papers and demos included deal with modeling and transformations and translations.

Table of Contents


Keynote: Martin Erwig

A Language for Software Variation Research

Variation occurs in many places in software engineering and takes quite different forms. Software can have different versions, and it can come in different configurations. Software can offer different sets of features, and it can appear in different stages of refactoring without any visible effect in functionality. Traditionally, all these forms of variation have used different representations.While this specialization might have some benefits by facilitating the tailoring to the specific needs of one form of variation, it has also some serious drawbacks. First, different representations prevent or complicate a potential integration of different forms of variation. For example, variation in functionality is currently only poorly supported in most versioning tools by branching. Second, it can be difficult to transfer research results achieved within one representation to other representations. Finally, different representations can lead to duplicated work and a balkanization of variation research efforts.
Martin Erwig


Automated Selective Caching for Reference Attribute Grammars

Reference attribute grammars (RAGs) can be used to express semantics as super-imposed graphs on top of abstract syntax trees (ASTs). A RAG-based AST can be used as the in-memory model providing semantic information for software language tools such as compilers, refactoring tools, and meta-modeling tools. RAG performance is based on dynamic attribute evaluation with caching. Caching all attributes gives optimal performance in the sense that each attribute is evaluated at most once. However, performance can be further improved by a selective caching strategy, avoiding caching overhead where it does not pay off. In this paper we present a profiling-based technique for automatically finding a good cache configuration. The technique has been evaluated on a generated Java compiler, compiling programs from the Jacks test suite and the DaCapo benchmark suite.
Emma Söderberg, Görel Hedin

Reference Attribute Grammars for Metamodel Semantics

While current metamodelling languages are well-suited for the structural definition of abstract syntax and metamodelling platforms like the Eclipse Modelling Framework (EMF) provide various means for the specification of a textual or graphical concrete syntax, techniques for the specification of model semantics are not as matured. Therefore, we propose the application of reference attribute grammars (RAGs) to alleviate the lack of support for formal semantics specification in metamodelling. We contribute the conceptual foundations to integrate metamodelling languages and RAGs, and present JastEMF – a tool for the specification of EMF metamodel semantics using JastAdd RAGs. The presented approach is exemplified by an integrated metamodelling example. Its advantages, disadvantages and limitations are discussed and related to metamodelling, attribute grammars (AGs) and other approaches for metamodel semantics.
Christoff Bürger, Sven Karol, Christian Wende, Uwe Aßmann

Modelling GLL Parser Implementations

We describe the development of space-efficient implementations of GLL parsers, and the process by which we refine a set-theoretic model of the algorithm into a practical parser generator that creates practical parsers. GLL parsers are recursive descent-like, in that the structure of the parser’s code closely mirrors the grammar rules, and so grammars (and their parsers) may be debugged by tracing the running parser in a debugger. While GLL recognisers are straightforward to describe, full GLL parsers present technical traps and challenges for the unwary. In particular, naïve implementations based closely on the theoretical description of GLL can result in data structures that are not practical for grammars for real programming language grammars such as ANSI-C. We develop an equivalent formulation of the algorithm as a high-level set-theoretic model supported by table-based indices, in order to then explore a set of alternative implementations which trade space for time in ways which preserve the cubic bound.
Adrian Johnstone, Elizabeth Scott


Metamodel Usage Analysis for Identifying Metamodel Improvements

Modeling languages raise the abstraction level at which software is built by providing a set of constructs tailored to the needs of their users. Metamodels define their constructs and thereby reflect the expectations of the language developers about the use of the language. In practice, language users often do not use the constructs provided by a metamodel as expected by language developers. In this paper, we advocate that insights about how constructs are used can offer language developers useful information for improving the metamodel. We define a set of usage and improvement patterns to characterize the use of the metamodel by the built models. We present our experience with the analysis of the usage of seven metamodels (EMF, GMF, UNICASE) and a large corpus of models. Our empirical investigation shows that we identify mismatches between the expected and actual use of a language that are useful for metamodel improvements.
Markus Herrmannsdoerfer, Daniel Ratiu, Maximilian Koegel

Domain-Specific Modelling Languages with Algebraic Graph Transformations on RDF

Domain-specific modelling langugages (DSMLs), which are tailored to the requirements of their users, can significantly increase the acceptance of formal (or at least semi-formal) modelling in scenarios where informal drawings and natural language descriptions are predominant today. We show in this paper how the Resource Description Framework (RDF), which is a standard for the fundamental data structures of the Semantic Web, and algebraic graph transformations on these data structures can be used to realise the abstract syntax of such DSMLs. We examine a small DSML for IT infrastructures as an application scenario. From this scenario, we derive distributed modelling, evolution of language definitions, migration of legacy models and integration of modelling languages as key requirements for a DSML framework. RDF and transformation rules are then used to provide a solution, which meets these requirements, where all kinds of modifications-from simple editing steps via model migration to language integration-are realised by the single, uniform formalism of algebraic graph transformation.
Benjamin Braatz, Christoph Brandt

Feature and Meta-Models in Clafer: Mixed, Specialized, and Coupled

We present Clafer, a meta-modeling language with first-class support for feature modeling. We designed Clafer as a concise notation for meta-models, feature models, mixtures of meta- and feature models (such as components with options), and models that couple feature models and meta-models via constraints (such as mapping feature configurations to component configurations or model templates). Clafer also allows arranging models into multiple specialization and extension layers via constraints and inheritance. We identify four key mechanisms allowing a meta-modeling language to express feature models concisely and show that Clafer meets its design objectives using a sample product line. We evaluated Clafer and how it lends itself to analysis on sample feature models, meta-models, and model templates of an E-Commerce platform.
Kacper Bąk, Krzysztof Czarnecki, Andrzej Wąsowski


Support for the Evolution of C++ Generic Functions

The choice of requirements for an argument of a generic type or algorithm is a central design issue in generic programming. In the context of C++, a specification of requirements for a template argument or a set of template arguments is called a concept.
In this paper, we present a novel tool, TACE (template analysis and concept extraction), designed to help programmers understand the requirements that their code de facto imposes on arguments and help simplify and generalize those through comparisons with libraries of well-defined and precisely-specified concepts. TACE automatically extracts requirements from the body of function templates. These requirements are expressed using the notation and semantics developed by the ISO C++ standards committee. TACE converts implied requirements into concept definitions and compares them against concepts from a repository. Components of a well-defined library exhibit commonalities that allow us to detect problems by comparing requirements from many components: Design and implementation problems manifest themselves as minor variations in requirements. TACE points to source code that cannot be constrained by concepts and to code where small modifications would allow the use of less constraining concepts. For people who use a version of C++ with concept support, TACE can serve as a core engine for automated source code rejuvenation.
Peter Pirkelbauer, Damian Dechev, Bjarne Stroustrup

Automated Co-evolution of GMF Editor Models

The Eclipse Graphical Modeling (GMF) Framework provides the major approach for implementing visual languages on top of the Eclipse platform. GMF relies on a family of modeling languages to describe abstract syntax, concrete syntax as well as other aspects of the visual language and its implementation in an editor. GMF uses a model-driven approach to map the different GMF models to Java code. The framework, as it stands, lacks support for evolution. In particular, there is no support for propagating changes from the domain model (i.e., the abstract syntax of the visual language) to other editor models. We analyze the resulting co-evolution challenge, and we provide a solution by means of GMF model adapters, which automate the propagation of domain-model changes. These GMF model adapters are special model-to-model transformations that are driven by difference models for domain-model changes.
Davide Di Ruscio, Ralf Lämmel, Alfonso Pierantonio

An Extensive Catalog of Operators for the Coupled Evolution of Metamodels and Models

Modeling languages and thus their metamodels are subject to change. When a metamodel is evolved, existing models may no longer conform to it. Manual migration of these models in response to metamodel evolution is tedious and error-prone. To significantly automate model migration, operator-based approaches provide reusable coupled operators that encapsulate both metamodel evolution and model migration. The success of an operator-based approach highly depends on the library of reusable coupled operators it provides. In this paper, we thus present an extensive catalog of coupled operators that is based both on a literature survey as well as real-life case studies. The catalog is organized according to a number of criteria to ease assessing the impact on models as well as selecting the right operator for a metamodel change at hand.
Markus Herrmannsdoerfer, Sander D. Vermolen, Guido Wachsmuth

JTL: A Bidirectional and Change Propagating Transformation Language

In Model Driven Engineering bidirectional transformations are considered a core ingredient for managing both the consistency and synchronization of two or more related models. However, while non-bijectivity in bidirectional transformations is considered relevant, current languages still lack of a common understanding of its semantic implications hampering their applicability in practice.
In this paper, the Janus Transformation Language (JTL) is presented, a bidirectional model transformation language specifically designed to support non-bijective transformations and change propagation. In particular, the language propagates changes occurring in a model to one or more related models according to the specified transformation regardless of the transformation direction. Additionally, whenever manual modifications let a model be non reachable anymore by a transformation, the closest model which approximate the ideal source one is inferred. The language semantics is also presented and its expressivity and applicability are validated against a reference benchmark. JTL is embedded in a framework available on the Eclipse platform which aims to facilitate the use of the approach, especially in the definition of model transformations.
Antonio Cicchetti, Davide Di Ruscio, Romina Eramo, Alfonso Pierantonio

Keynote: Abraham Bernstein

Software Engineering and the Semantic Web: A Match Made in Heaven or in Hell?

The Semantic Web provides models and abstractions for the distributed processing of knowledge bases. In Software Engineering endeavors such capabilities are direly needed, for ease of implementation, maintenance, and software analysis.
Conversely, software engineering has collected decades of experience in engineering large application frameworks containing both inheritance and aggregation. This experience could be of great use when, for example, thinking about the development of ontologies.
These examples—and many others—seem to suggest that researchers from both fields should have a field day collaborating: On the surface this looks like a match made in heaven. But is that the case?
This talk will explore the opportunities for cross-fertilization of the two research fields by presenting a set of concrete examples. In addition to the opportunities it will also try to identify cases of fools gold (pyrite), where the differences in method, tradition, or semantics between the two research fields may lead to a wild goose chase.
Abraham Bernstein


A Unified Format for Language Documents

We have analyzed a substantial number of language documentation artifacts, including language standards, language specifications, language reference manuals, as well as internal documents of standardization bodies. We have reverse-engineered their intended internal structure, and compared the results. The Language Document Format (LDF), was developed to specifically support the documentation domain. We have also integrated LDF into an engineering discipline for language documents including tool support, for example, for rendering language documents, extracting grammars and samples, and migrating existing documents into LDF. The definition of LDF, tool support for LDF, and LDF applications are freely available through SourceForge.
Vadim Zaytsev, Ralf Lämmel

Canonical Method Names for Java

Using Implementation Semantics to Identify Synonymous Verbs
Programmers rely on the conventional meanings of method names when writing programs. However, these conventional meanings are implicit and vague, leading to various forms of ambiguity. This is problematic since it hurts the readability and maintainability of programs. Java programmers would benefit greatly from a more well-defined vocabulary. Identifying synonyms in the vocabulary of verbs used in method names is a step towards this goal. By rooting the meaning of verbs in the semantics of a large number of methods taken from real-world Java applications, we find that such synonyms can readily be identified. To support our claims, we demonstrate automatic identification of synonym candidates. This could be used as a starting point for a manual canonicalisation process, where redundant verbs are eliminated from the vocabulary.
Einar W. Høst, Bjarte M. Østvold


Bringing Context to Mobile Platform Programming
Thanks to steady advances in hardware, mobile computing platforms are nowadays much more connected to their physical and logical environment than ever before. To ease the construction of adaptable applications that are smarter with respect to their execution environment, the context-oriented programming paradigm has emerged. However, up until now there has been no proof that this emerging paradigm can be implemented and used effectively on mobile devices, probably the kind of platform which is most subject to dynamically changing contexts. In this paper we study how to effectively realise core context-oriented abstractions on top of Objective-C, a mainstream language for mobile device programming. The result is Subjective-C, a language which goes beyond existing context-oriented languages by providing a rich encoding of context interdependencies. Our initial validation cases and efficiency benchmarks make us confident that context-oriented programming can become mainstream in mobile application development.
Sebastián González, Nicolás Cardozo, Kim Mens, Alfredo Cádiz, Jean-Christophe Libbrecht, Julien Goffaux

Short Papers and Demos: Modeling

The Level-Agnostic Modeling Language

As an alternative modeling infrastructure and paradigm, multi-level modeling addresses many of the conceptual weaknesses found in the four level modeling infrastructure that underpins traditional modeling approaches like UML and EMF. It does this by explicitly distinguishing between linguistic and ontological forms of classification and by allowing the influence of classifiers to extend over more than one level of instantiation. Multi-level modeling is consequently starting to receive attention from a growing number of research groups. However, there has never been a concrete definition of a language designed from the ground-up for the specific purpose of representing multi-level models. Some authors have informally defined the “look and feel” of such a language, but to date there has been no systematic or fully elaborated definition of its concrete syntax. In this paper we address this problem by introducing the key elements of a language, known as the Level-Agnostic Modeling Language (LML) designed to support multi-level modeling.
Colin Atkinson, Bastian Kennel, Björn Goß

Debugging in Domain-Specific Modelling

An important obstacle to the wide-spread adoption of model-driven development approaches in industry is the lack of proper debugging facilities. Software debugging support is provided by a combination of language and Integrated Development Environment (IDE) features which enable the monitoring and altering of a running program’s state. In Domain-Specific Modelling (DSM), debugging activities have a wider scope: designers debug model transformations (MTs) and synthesized artifacts, while domain-specific modellers debug their models, unaware of generated artifacts. This work surveys the state-of-the-art of debugging in the context of DSM and proposes a mapping between debugging concepts (e.g., breakpoints, assertions) in the software and DSM realms.
Raphael Mannadiar, Hans Vangheluwe

COPE – A Workbench for the Coupled Evolution of Metamodels and Models

Model-driven software development promises to increase productivity by offering modeling languages tailored to a problem domain. Consequently, an increasing number of modeling languages are built using metamodel-based language workbenches. In response to changing requirements and technologies, the modeling languages and thus their metamodels need to be adapted. Manual migration of existing models in response to metamodel adaptation is tedious and error-prone. In this paper, we present our tool COPE to automate the coupled evolution of metamodels and models. To not lose the intention behind the adaptation, COPE records the coupled evolution in an explicit history model. Based on this history model, COPE provides advanced tool support to inspect, refactor and recover the coupled evolution.
Markus Herrmannsdoerfer

Short Papers and Demos: Transformations and Translations

DSLTrans: A Turing Incomplete Transformation Language

In this paper we present DSLTrans: a visual language and a tool for model transformations. We aim at tackling a couple of important challenges in model transformation languages — transformation termination and confluence. The contribution of this paper is the proposition of a transformation language where all possible transformations are guaranteed to be terminating and confluent by construction. The resulting transformation language is simple, turing incomplete and includes transformation abstractions to support transformations in a software language engineering context. Our explanation of DSLTrans includes a complete formal description of our visual language and its properties.
Bruno Barroca, Levi Lúcio, Vasco Amaral, Roberto Félix, Vasco Sousa

Translator Generation Using ART

ART (Ambiguity Resolved Translators) is a new translator generator tool which provides fast generalised parsing based on an extended GLL algorithm and automatic generation of tree traversers for manipulating abstract syntax. The input grammars to ART comprise modular sets of context free grammar rules, enhanced with regular expressions and annotations that describe disambiguation and tree modification operations using the TIF (Tear-Insert-Fold) formalism. ART generates a GLL parser for the input grammar along with an output grammar whose derivation trees are the abstract trees specified by the TIF tree modification operations.
Adrian Johnstone, Elizabeth Scott

Empirical Language Analysis in Software Linguistics

Software linguistics is the science of software languages. In this short paper, we sketch the general discipline of software linguistics, but our focus is on one part of it: empirical analysis of software languages. Such analysis is concerned with understanding language usage on the grounds of a corpus. In this short paper, we sketch a survey on empirical language analysis, and we argue that the research method of content analysis is needed for a thorough survey.
Jean-Marie Favre, Dragan Gasevic, Ralf Lämmel, Ekaterina Pek

Interactive Disambiguation of Meta Programs with Concrete Object Syntax

In meta-programming with concrete object syntax, meta programs can be written using the concrete syntax of manipulated programs. Quotations of concrete syntax fragments and anti-quotations for meta-level expressions and variables are used to manipulate the abstract representation of programs. These small, isolated fragments are often ambiguous and must be explicitly disambiguated with quotation tags or types, using names from the non-terminals of the object language syntax. Discoverability of these names has been an open issue, as they depend on the (grammar) implementation and are not part of the concrete syntax of a language. Based on advances in interactive development environments, we introduce interactive disambiguation to address this issue, providing real-time feedback and proposing quick fixes in case of ambiguities.
Lennart C. L. Kats, Karl T. Kalleberg, Eelco Visser

Domain-Specific Languages

Evaluating a Textual Feature Modelling Language: Four Industrial Case Studies

Feature models are commonly used in software product line engineering as a means to document variability. Since their introduction, feature models have been extended and formalised in various ways. The majority of these extensions are variants of the original tree-based graphical notation. But over time, textual dialects have also been proposed. The textual variability language (TVL) was proposed to combine the advantages of both graphical and textual notations. However, its benefits and limitations have not been empirically evaluated up to now. In this paper, we evaluate TVL with four cases from companies of different sizes and application domains. The study shows that practitioners can benefit from TVL. The participants appreciated the notation, the advantages of a textual language and considered the learning curve to be gentle. The study also reveals some limitations of the current version of TVL.
Arnaud Hubaux, Quentin Boucher, Herman Hartmann, Raphaël Michel, Patrick Heymans

Extending DMM Behavior Specifications for Visual Execution and Debugging

Dynamic Meta Modeling (DMM) is a visual semantics specification technique targeted at behavioral languages equipped with a metamodel defining the language’s abstract syntax. Given a model and a DMM specification, a transition system can be computed which represents the semantics of that model. It allows for the investigation of the model’s behavior, e.g. for the sake of understanding the model’s semantics or to verify that certain requirements are fulfilled. However, due to a number of reasons such as tooling and the size of the resulting transition systems, the manual inspection of the resulting transition system is cumbersome.
One solution would be a visualization of the model’s behavior using animated concrete syntax. In this paper, we show how we have enhanced DMM such that visual execution and debugging can be added to a language in a simple manner.
Nils Bandener, Christian Soltenborn, Gregor Engels

Analysing the Cognitive Effectiveness of the BPMN 2.0 Visual Notation

BPMN 2.0 is an OMG standard and one of the leading process modelling notations. Although the current language specification recognises the importance of defining a visual notation carefully, it does so by relying on common sense, intuition and emulation of common practices, rather than by adopting a rigorous scientific approach. This results in a number of suboptimal language design decisions that may impede effective model-mediated communication between stakeholders. We demonstrate and illustrate this by looking at BPMN 2.0 through the lens of the Physics of Notations, a collection of evidence-based principles that together form a theory of notation design. This work can be considered a first step towards making BPMN 2.0’s visual notation more cognitively effective.
Nicolas Genon, Patrick Heymans, Daniel Amyot

Featherweight TeX and Parser Correctness

TeX (and its LaTeX incarnation) is a widely used document preparation system for technical and scientific documents. At the same time, TeX is also an unusual programming language with a quite powerful macro system. Despite the wide range of TeX users (especially in the scientific community), and despite a widely perceived considerable level of “pain” in using TeX, there is almost no research on TeX. This paper is an attempt to change that.
To this end, we present Featherweight TeX, a formal model of TeX which we hope can play a similar role for TeX as Featherweight Java did for Java. The main technical problem which we study in terms of Featherweight TeX is the parsing problem. As for other dynamic languages performing syntactic analysis at runtime, the concept of “static” parsing and its correctness is unclear in TeX and shall be clarified in this paper. Moreover, it is the case that parsing TeX is impossible in general, but we present evidence that parsers for practical subsets exists.
We furthermore outline three immediate applications of our formalization of TeX and its parsing: a macro debugger, an analysis that detects syntactic inconsistencies, and a test framework for TeX parsers.
Sebastian Thore Erdweg, Klaus Ostermann


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