Implementation of visual languages using pattern‐based specifications

The implementation of visual languages requires a wide range of conceptual and technical knowledge from issues of user interface design and graphical implementation to aspects of analysis and transformation for languages in general. We present a powerful toolset that incorporates such knowledge. Our toolset generates editors from high‐level specifications. A language is specified by identifying certain patterns in the language structure and selecting a visual representation from a set of precoined solutions. Visual programs are represented by attributed abstract trees. Therefore, further phases of processing visual programs can be generated by state‐of‐the‐art tools for language implementation. We demonstrate that even challenging visual languages can be implemented with reasonably little effort and with rather limited technical knowledge. The approach is suitable for a large variety of visual language styles. Copyright © 2003 John Wiley & Sons, Ltd.     

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.     

Early experience with the Visual Programmer's WorkBench

The Visual Programmer's WorkBench (VPW) addresses the rapid synthesis and customization of environments for the specification, analysis, and execution of visual programs. The goal of VPW is to enable the easy creation of environments for visual languages. The design of VPW and experience using it to generate a distributed programming environment for a concurrent visual language are described. A visual programming environment for the PetriFSA language generated with VPW is outlined. An overview is provided of the language definition model and its relation to the logical architecture of VPW. Details are given of the language specifications used in VPW, and its application in defining the PetriFSA language. A language-based environment for a specific visual language is generated in VPW from a specification of the syntactic structure, the abstract structure, the static semantics, and the dynamic semantics of the language. VPW is built around a model of distributed processing based on a shared distributed memory. This framework is used in defining the architecture of the environment and for the execution model of visual languages     

Automatic generation of visual programming environments

We have developed the visual language compiler-compiler (VLCC) system to automatically generate visual programming environments. VLCC is a grammar based system that can support implementation of any visual language by assisting the language designer in defining the language's graphical objects, syntax, and semantics. The final result of the generation process includes an integrated environment with a visual editor and a compiler for the defined visual language. In VLCC, graphical tools define visual languages to create both graphical objects and composition rules. Visual editors enable language designers to directly and visually manipulate the syntax of these languages. To capture the widest range of visual languages, the VLCC system can be configured for a specific language class. Different language classes can be characterized depending on their graphical objects' structure and on the way they can be composed. Also, box and arrow diagrams are defined for primitive objects with attaching points and for composition rules to join boxes and arrows at those attaching points. After choosing the visual language type to create, the designer can concentrate on language definition details. VLCC uses the positional grammar model as its underlying grammar formalism     

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.     

ＶＦＰ过程蓝图设计技术

Ｖisual FoxPro过程蓝科是一种面向Ｖisual FoxPro语言的程序处理逻辑图表化表示法,这种工程化表示法支持逻辑和实现两个层次的程序抽象表示,是一种简单实用、容易理解、结构良好的程序设计工具,并给出Ｖisual FoxPro过程蓝图的形式化模型和抽象逻辑结构图的图形表示方法。     

Specifying Graph-like Diagrams with Dia Gne

This extended abstract demonstrates that creating editors and environments for visual languages becomes considerably easier when restricting the class of visual languages. The presented approach considers graph-like languages whose diagrams consist of nodes and edges with different types. The specification method allows to describe such graphs in terms of their node and edge types and makes use of constraints in order to express syntactic properties. The DIA GEN system is used to generate running editors from such specifications.     

可视化语言文法形式化描述综述

可视化是人机交互的主要形式,可视化语言是计算机科学中一个重要研究领域,文法为可视化语言提供了一种有价值的形式化描述方法。本文基于可视化语言的特征,介绍了可视化语言文法形式化描述体系的基本理论,分析了几种典型形式模型,并探讨了当前的主要研究内容和面临的挑战。     

Miro: visual specification of security

Miro is a set of languages and tools that support the visual specification of file system security. Two visual languages are presented: the instance language, which allows specification of file system access, and the constraint language, which allows specification of security policies. Miro visual languages and tools are used to specify security configurations. A visual language is one whose entities are graphical, such as boxes and arrows, specifying means stating independently of any implementation the desired properties of a system. Security means file system protection: ensuring that files are protected from unauthorized access and granting privileges to some users, but not others. Tools implemented and examples of how these languages can be applied to real security specification problems are described     

VB过程蓝图

ＶＢ过程蓝图是一种面向Ｖｉｓｕａｌ　Ｂａｓｉｃ语言的程序处理逻辑图表化表示法。这种工程化表示法支持 逻辑和实现两个层次的程序抽象表示,是一种简单实用、容易理解、结构良好的程序设计工具。文中 给出ＶＢ过程蓝图的形式化模型,抽象逻辑结构图的图形表示方法,以及程序设计的基本过程。     

A Classification Framework to Support the Design of Visual Languages

An important step in the design of visual languages is the specification of the graphical objects and the composition rules for constructing feasible visual sentences. The presence of different typologies of visual languages, each with specific graphical and structural characteristics, yields the need to have models and tools that unify the design steps for different types of visual languages. To this aim, in this paper we present a formal framework of visual language classes. Each class characterizes a family of visual languages based upon the nature of their graphical objects and composition rules. The framework has been embedded in the Visual Language Compiler–Compiler (VLCC), a graphical system for the automatic generation of visual programming environments.     

Extending local context-based specifications of visual languages

In this paper we present a framework for the fast prototyping of visual languages exploiting their local context based specification.In previous research, the local context specification has been used as a weak form of syntactic specification to define when visual sentences are well formed. In this paper we add new features to the local context specification in order to fully specify complex constructs of visual languages such as entity-relationships, use case and class diagrams. One of the advantages of this technique is its simplicity of application and, to show this, we present a tool implementing our framework.Moreover, we describe a user study aimed at evaluating the effectiveness and the user satisfaction when prototyping a visual language.     

An approach to the formal specification of computer graphics systems

This paper discusses the approach to formal specification of computer graphics systems developed by the ANSI X3H3 committee (Computer Graphics Programming Languages) in the United States. ANSI's specification philosophy aims to gradually replace existing informal English language specifications with more formal ones without sacrificing the readibility and usefulness of standards documents. The specification techniques used are derived from those presently employed in the specification of computer communication protocols and the specification of software systems, not those used for the specification of programming languages. The specifications consist of three parts: the interface between both graphics and the host language and graphics and the graphical display device, the structure of the graphics system, and the functions that are performed by the graphics system. The specifications are based on abstract data types. These data types, together with the operations which can be performed on them, are used to describe the structure and functions of the graphics system. Using these techniques, X3H3 has developed a complete formal specification for a minimal graphics system. Extracts from this specification are included here.     

Formalizing visual interaction with historical databases

Recent database applications are typically oriented towards a large set of non-expert users, and therefore, they need to be equipped with suitable interfaces facilitating the interaction with the system. Moreover, the incorporation of the time dimension in database systems is a desirable feature. Indeed, several temporal data models and the corresponding textual query languages have been proposed. However, there is a limited amount of research concerning the investigation of user-oriented languages for querying temporal databases. Our proposal addresses such a need. In particular, we propose a visual query environment, namely Temporal Visual Query Environment (TVQE) which provides an easier interaction of the user with temporal databases. The system adopts a diagrammatic representation of the database schema (including temporal classes and relationships) and a “graphical notebook” as interaction metaphor. In our approach, non-database experts are released from syntactical difficulties which are typical of textual languages, and they can easily express temporal queries by means of elementary graphical operations (e.g. click on a node label). Differently from many proposals in the field of visual query languages, the language underlying TVQE is provided with formal syntax and semantics. It is based on a minimal set of temporal graphical primitives (TGPs), which are defined on a Temporal Graph Model (TGM), with visual syntax and object-based semantics. In this paper we mainly concentrate on the formal aspects of TVQE, and provide some hints on the visual interaction mechanisms and implementation issues.     

Query by diagram: A visual environment for querying databases

In recent years, several attempts have been made to define query languages characterized by both high expressive power and easy query formulation. Several issues concern graphical applications, based on the diagrammatic representation of a semantic model and visual interaction. This paper describes the architecture and the implementation of a graphical query system, based on the diagrammatic representation of entity relationship schemata. The query language underlying the system allows the formulation of recursive queries; moreover, user interaction in both managing diagrams and expressing queries is simplified by the presence of a fully visual environment and a rich set of interaction strategies.     

Implementation of rule-based information systems for integratedmanufacturing

Focuses on the development of a methodology within a software environment for automating the rule-based implementation of specifications of integrated manufacturing information systems. The specifications are initially formulated in a natural language and subsequently represented in terms of a graphical representation by the system designer. A new graphical representation tool is based on updated Petri nets (UPN) that we have developed as a specialized version of colored Petri nets. The rule-based implementation approach utilizes the similarity of features between UPN and the general rule specification language used for the implementation. The automation of the translation of UPN to the rule specification language is expected to considerably reduce the life-cycle for design and implementation of the system. The application presented deals with the control and management of information flow between the computer-aided design, process planning, manufacturing resource planning and shop floor control databases. This provides an integrated information framework for computer integrated manufacturing systems     

ALCHEMIST: A General Purpose Transformation Generator

ALCHEMIST is a general purpose transformation generating environment, which supports specification, generation and execution of data transformations. ALCHEMIST allows an abstract specification of the transformation through a window-based interface and supports the generation and compilation of transformation program code from these specifications. Unlike compiler-compilers, ALCHEMIST is intended to automate building transformations between two complex representation formats and is thus especially suitable for constructing transformations between database tools, CASE tools, graphical editors or text formatters. In this paper we describe the design principles and the structure of ALCHEMIST, and demonstrate its use. We also discuss our experiences with several example transformations and present a real-life case study of using ALCHEMIST for interfacing two software development environments.     

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.