Towards Syntax-Aware Editors for Visual Languages

Editors for visual languages should provide a user-friendly environment supporting end users in the composition of visual sentences in an effective way. Syntax-aware editors are a class of editors that prompt users into writing syntactically correct programs by exploiting information on the visual language syntax. In particular, they do not constrain users to enter only correct syntactic states in a visual sentence. They merely inform the user when visual objects are syntactically correct. This means detecting both syntax and potential semantic errors as early as possible and providing feedback on such errors in a non-intrusive way during editing. As a consequence, error handling strategies are an essential part of such editing style of visual sentences.In this work, we develop a strategy for the construction of syntax-aware visual language editors by integrating incremental subsentence parsers into free-hand editors. The parser combines the LR-based techniques for parsing visual languages with the more general incremental Generalized LR parsing techniques developed for string languages. Such approach has been profitably exploited for introducing a noncorrecting error recovery strategy, and for prompting during the editing the continuation of what the user is drawing.     

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.     

Visual Language Parsing in GenGEd

GenGEd supports the visual specification of visual languages and the generation of syntax-directed editors. However, syntax-directed editing is not always desired by the user. Therefore we extended GenGEd by parsing facilities which allow for free editing as well.     

A bootstrap approach to visual user-interface design and development

An approach to the design of effective computer-based systems is discussed. This approach exploits the user's traditional diagrammatic notations in an effort to achieve usability for experts other than computer professionals. Notations are formalized as visual languages, thus allowing the design of visual editors, interpreters, and compilers. The users themselves exploit these tools to define a hierarchy of environments by a bootstrapping approach. By navigating within these environments, they can progressively design visual interfaces and computing tools that allow them not only to execute the required computational tasks, but also to gain insight into and control the computational process, and check the results.     

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     

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.     

Pictorial Representation and Metaphor in Visual Language Design

This paper reports the results of seven different experiments, assessing the benefit that users gain from the inclusion of pictorial features such as pictorial metaphor, visual mnemonics or support for visual imagery in visual languages. The experiments are based on typical programming tasks such as problem solving, construction and interpretation. They employed a number of experimental languages, including both implicit pictorial representations and explicitly verbal metaphorical explanations. The results of these experiments indicate that special design considerations apply to visual languages. Direct application of Graphical User Interface metaphors does not result in automatic improvements in usability of visual languages for typical programming tasks. Visual languages can benefit from pictorial mnemonics, but systematic explanatory metaphors (whether visual or verbal) are less useful than consistent presentation of language abstractions.     

可视化查询语言CQL的实现

为使得许多非计算机专业的用户,尤其是未接受过数据库编程语言训练的用户,能够独立操纵一个数据库系统,有效地解决工作、生活中的问题,我们研究并提供了一种空间数据库可视化查询语言CQL。借助该语言,用户可以直观、方便地操纵数据库系统或查询数据库信息。本文介绍了CQL语言的语素、语义、语法及语用的定义,同时给出了CQL编辑器、编译器和查询结果可视化的设计方法。     

A Principled Approach to Grammars for Controlled Natural Languages and Predictive Editors

Controlled natural languages (CNL) with a direct mapping to formal logic have been proposed to improve the usability of knowledge representation systems, query interfaces, and formal specifications. Predictive editors are a popular approach to solve the problem that CNLs are easy to read but hard to write. Such predictive editors need to be able to “look ahead” in order to show all possible continuations of a given unfinished sentence. Such lookahead features, however, are difficult to implement in a satisfying way with existing grammar frameworks, especially if the CNL supports complex nonlocal structures such as anaphoric references. Here, methods and algorithms are presented for a new grammar notation called Codeco, which is specifically designed for controlled natural languages and predictive editors. A parsing approach for Codeco based on an extended chart parsing algorithm is presented. A large subset of Attempto Controlled English has been represented in Codeco. Evaluation of this grammar and the parser implementation shows that the approach is practical, adequate and efficient.     

CEViNEdit: improving the process of creating cognitively effective graphical editors with GMF

Software and Systems Modeling - The rise of domain-specific (Visual) languages and the inherent complexity of developing graphical editors for these languages have led to the emergence of proposals...     

面向对象的逻辑图示语言

本语言介绍了图示语言基本概念及其特点，在事件驱动机制的基础上提出了逻辑驱动机制和多表达式结构，对函数式语言、逻辑语言和面向对象语言进行了理论上的分析，提出了它们在本质相容性和统一性并阐述了这三种技术在我们开发的逻辑图示语言Ｖｉｌｏｇ中的结合。     

Time Automaton: A visual mechanism for temporal querying

Available visual temporal querying tools do not provide the means for formulating complex temporal queries. For these queries users have to adopt text-based querying languages, such as SQL. The problem, however, is that using text-based languages is less comfortable than using visual tools and, most important, in some cases temporal queries can be extremely difficult to formulate for users that do not possess programming competences. In this paper we propose the Time Automaton, a highly flexible visual mechanism that enables the formulation of a large set of different types of temporal queries, ranging from the simple to the most complex ones. To prove its practical application we created a tool that implements the mechanism and used it to analyze a real dataset. Time Automaton was validated against a representative sample of temporal queries extracted from the matured OWL-Time Ontology. In order to understand if users, with or without programming competences, could understand and use the Time Automaton we conducted a usability experiment.     

Exploiting XPG for Visual Languages Definition, Analysis and Development

In this paper we present the approach based on the formalism of Extended Positional Grammars (XPG) for specifying, designing and implementing visual languages. Special emphasis is put on describing the benefits deriving from the use of such formalism. Indeed, it allows us to exploit the well-established theoretical background and techniques developed for string languages in the setting of visual languages. As a matter of fact, an efficient syntactic analysis of visual languages can be effectively perfomed by using a suitable extension of LR techniques. Moreover, syntax-direct translations can be used to verify properties of visual sentences during a semantic analysis phase. Finally, a visual environment for a target visual language can be automatically generated by exploiting a YACC-like tool based on XPG.     

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     

Leveraging declarative languages in web application development

Web Applications have become an omnipresent part of our daily lives. They are easy to use, but hard to develop. WYSIWYG editors, form builders, mashup editors, and markup authoring tools ease the development of Web Applications. However, more advanced Web Applications require servers-side programming, which is beyond the skills of end-user developers. In this paper, we discuss how declarative languages can simplify Web Application development and empower end-users as Web developers. We first identify nine end-user Web Application development levels ranging from simple visual customization to advanced three-tier programming. Then, we propose expanding the presentation tier to support all aspects of Web Application development. We introduce a unified XForms-based framework—called XFormsDB—that supports both client-side and server-side Web Application development. Furthermore, we make a language extension proposal—called XFormsRTC—for adding true real-time communication capabilities to XForms. We also present XFormsDB Integrated Development Environment (XIDE), which assists end-users in authoring highly interactive data-driven Web Applications. XIDE supports all Web Application development levels and, especially, promotes the transition from markup authoring and snippet programming to single and unified language programming.     

On the Geometric Modelling of Visual Languages

We present arguments for the complementary role that intrinsically geometric models of visual languages can play in many applications, alongside non-geometry based models (such those based on graph grammars, logical predicates or algebraic structures). We characterise which models are intrinsically geometric, and illustrate the concept by providing such a model for higraphs. Further, we examine the relevance of geometric models to the design and implementation of tools which effectively support users in working with visual languages.     

Building syntax-aware editors for visual languages

Syntax-aware editors are a class of editors prompting users into writing syntactically correct programs by exploiting visual language syntax. They are particularly useful in those application domains where the way a visual symbol spatially relates to others depends from the context. This does not mean constraining users to enter only correct syntactic states in a visual sentence, rather it means detecting both syntax and potential semantic errors as early as possible, and providing error feedbacks in a non-intrusive way during editing. As a consequence, error handling strategies are an essential part of this editing style.In this work, we present a strategy for the automatic generation of syntax-aware visual language editors integrating incremental subsentence parsers into freehand editors. The proposed parsing strategy has turned out to be useful in many application domains involving spatial information systems, thanks to the possibility of interactively prompting feasible visual sentence extensions, and to the presence of a non-correcting error recovery strategy. A first experimental prototype implementing the whole approach has been embedded into the VLDesk system, and empirical studies have been performed in order to verify the performance and the effectiveness of the proposed approach.     

Unscrambling non-sequential programs

Certain types of computer language popular in areas such as decision support systems have the property that language statements need not be written in execution sequence, as the correct evaluation order can be established by dependency analysis. The uncontrolled use of these ‘nonsequential’ languages can lead to the development of programs and systems that are difficult to comprehend and maintain. This paper describes a method of clustering such code statements into sequential (procedural) modules to clarify visual presentation. The technique is based on depth-first search of directed graphs and will group those statements which are most strongly related to each other into a module.