Automating visual language generation

A system to generate and interpret customized visual languages in given application areas is presented. The generation is highly automated. The user presents a set of sample visual sentences to the generator. The generator uses inference grammar techniques to produce a grammar that generalizes the initial set of sample sentences, and exploits general semantic information about the application area to determine the meaning of the visual sentences in the inferred language. The interpreter is modeled on an attribute grammar. A knowledge base, constructed during the generation of the system, is then consulted to construct the meaning of the visual sentence. The architecture of the system and its use in the application environment of visual text editing (inspired by the Heidelberg icon set) enhanced with file management features are reported     

Automating the construction of domain-specific modeling languages for object-oriented frameworks

The extension of frameworks with domain-specific modeling languages (DSML) has proved to be an effective way of improving the productivity in software product-line engineering. However, developing and evolving a DSML is typically a difficult and time-consuming task because it requires to develop and maintain a code generator, which transforms application models into framework-based code. In this paper, we propose a new approach for extending object-oriented frameworks that aims to alleviate this problem. The approach is based on developing an additional aspect-oriented layer that encodes a DSML for building framework-based applications, eliminating the need of implementing a code generator. We further show how a language workbench is capable of automating the construction of DSMLs using the proposed layer.     

Supporting user-oriented analysis for multi-view domain-specific visual languages

The integration of usable and flexible analysis support in modelling environments is a key success factor in Model-Driven Development. In this paradigm, models are the core asset from which code is automatically generated, and thus ensuring model correctness is a fundamental quality control activity. For this purpose, a common approach is to transform the system models into formal semantic domains for verification. However, if the analysis results are not shown in a proper way to the end-user (e.g. in terms of the original language) they may become useless.In this paper we present a novel DSVL called BaVeL that facilitates the flexible annotation of verification results obtained in semantic domains to different formats, including the context of the original language. BaVeL is used in combination with a consistency framework, providing support for all steps in a verification process: acquisition of additional input data, transformation of the system models into semantic domains, verification, and flexible annotation of analysis results.The approach has been validated analytically by the cognitive dimensions framework, and empirically by its implementation and application to several DSVLs. Here we present a case study of a notation in the area of Digital Libraries, where the analysis is performed by transformations into Petri nets and a process algebra.     

A visual environment for visual languages

The visual environment GENGED supports the visual definition of visual languages (VLs). Each VL is defined by an alphabet and a grammar. From a specific VL-definition, a VL-specification is generated which is the input of a graphical editor allowing for syntax-directed editing of diagrams over the specified VL. GENGED as well as each VL is based on the well-defined concepts of algebraic graph transformation and graphical constraint solving. The underlying formalism is hidden from the user, but it is essential for a formal presentation and manipulation of graphical structures. In this contribution, the GENGED concepts and environment are briefly proposed and illustrated by the definition of a simple kind of the well-known statechart language.     

State transformation-based dynamic visual servoing for an unmanned aerial vehicle

In this paper, we propose a visual servoing control for a quadrotor unmanned aerial vehicle (UAV) which is based on a state transformation technique. The UAV is equipped with a single downwards facing camera, and the motion control objective is the regulation of relative displacement and yaw to a stationary visual target located on the ground. The state transformation is defined by a system of partial differential equations (PDEs) which eliminate roll and pitch rate dependence in the transformed image feature kinematics. A method for computing the general solutions of these PDEs is given, and we show a particular solution reduces to an established virtual camera approach. We treat point and line cases and introduce image moment features defined in the virtual camera image plane. Robustness of the control design is improved by accounting for attitude measurement bias, and uncertainty in thrust gain, mass, and image feature depth. The asymptotic stability of the closed-loop is proven. The method is based on a simple proportional-integral-derivative (PID) structure which can be readily implemented on-board. Experimental results show improved performance relative to previous work.     

Scaling up visual programming languages

The directness, immediacy, and simplicity of visual programming languages are appealing. The question is, can VPLs be effectively applied to large scale programming problems while retaining these characteristics. In scaling up, the problem is how to expand applicability without sacrificing the goals of better logic expression and understanding. From a size standpoint, scaling up refers to the programmer's ability to apply VPLs in larger programs. Such programs range from those requiring several days' work by a single programmer to programs requiring months of work, large programming teams, and large data structures. From a problem domain standpoint, scaling up refers to suitability for many kinds of problems. These range from visual application domains-such as user interface design or scientific visualization-to general purpose programming in such diverse areas as financial planning, simulations, and real time applications with explicit timing requirements. To illustrate the scaling up problem, we discuss nine major subproblems and describe emerging solutions from existing VPL systems. First, we examine representation issues, including static representation, screen real estate, and documentation. Next, we examine programming language issues-procedural abstraction, interactive visual data abstraction, type checking, persistence, and efficiency. Finally, we look at issues beyond the coding process     

Modeling visual interactive systems through dynamic visual languages

Visual interaction processes are modeled in this paper as sequences of visual sentences in which for each visual sentence only a limited set of user actions is possible. We introduce the notion of "dynamic visual language" as a weakly ordered set of visual sentences characterized by the presence of common elements. We present a formal model of derivation of visual sentences in a dynamic visual language in which each visual sentence specifies the possible actions which can be performed on it and the possible transformations it can go through. In this way, we offer a formal setting in which the interaction process can be formally specified. A user interface can be derived from the formal specification, so that it embeds proper context elements which limit user disorientation. The concepts are illustrated by the user interaction with a prototype of a digital library developed at the University of Bari.     

Using visual languages in management

Recent great advances of information visualization and visual languages have not been utilized in the management field. This View point article advocates the use of appropriate visual languages in general and visualization in particular to maximize human's visual perceptual power for rapid and effective communication in management.     

Dynamic aspects of visual modelling languages

A large class of diagrammatic languages falls under the broad definition of “executable graphics”, meaning that some transformational semantics can be devised for them. On the other hand, the definition of static aspects of visual languages often relies on some form of parsing or constructive process. We propose here an approach to the definition of visual languages syntax and semantics based on a notion of transition as production/consumption of resources. Transitions can be represented in forms which are intrinsic to the diagrams or external to them. A collection of abstract metamodels is presented to discuss the approach.     

Defining visual languages for interactive computing

A novel definition of visual languages allows a uniform approach to satisfying the needs of visual reasoning faced in visual human-computer interaction. The way the machine associates a computational meaning with an image, and conversely, the way it generates an image on the screen from a computation are formally described. A definition of a visual sentence and of a visual language as a set of visual sentences is discussed. A hierarchy of visual languages is derived in relation to the requirements for intelligible, manageable and trustable interaction between humans and computers     

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.     

Automating the analysis of design component contracts

Software patterns are a new design paradigm used to solve problems that arise when developing software within a particular context. Patterns capture the static and dynamic structure and collaboration among the components in a software design. A key promise of the pattern‐based approach is that it may greatly simplify the construction of software systems out of building blocks and thus reuse experience and reduce cost. However, it also introduces significant problems in ensuring the integrity and reliability of these composed systems because of their complex software topologies, interactions and transactions. There is a need to capture these features as a contract through a formal model that allows us to analyze pattern‐based designs. In this paper, we provide an overview of a formal framework for ensuring the integrity of the compositions in object‐oriented designs by providing mathematically rigorous modeling and analysis techniques for object‐oriented systems comprising pattern‐based designs as the basic building blocks or design components. A case study related to a hypermedia Web‐based application has been presented to illustrate our approach in distributed systems. Copyright © 2005 John Wiley & Sons, Ltd.     

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.     

Cognitive effectiveness of visual instructional design languages

The introduction of learning technologies into education is making the design of courses and instructional materials an increasingly complex task. Instructional design languages are identified as conceptual tools for achieving more standardized and, at the same time, more creative design solutions, as well as enhancing communication and transparency in the design process. In this article we discuss differences in cognitive aspects of three visual instructional design languages (E²ML, PoEML, coUML), based on user evaluation. Cognitive aspects are of relevance for learning a design language, creating models with it, and understanding models created using it. The findings should enable language constructors to improve the usability of visual instructional design languages in the future. The paper concludes with directions with regard to how future research on visual instructional design languages could strengthen their value and enhance their actual use by educators and designers by synthesizing existing efforts into a unified modeling approach for VIDLs.     

Automating the analysis of variance of orthogonal designs

A new algorithm is presented which for the wide class of orthogonal designs is capable of deducing the appropriate analysis of variance from the design only. As a consequence the use of a model equation for specifying the analysis becomes dispensable. The proposed approach can simplify the analysis of complex models with iterative crossing and nesting of factors, where treatment factors have fixed and plot factors have random effects. An implementation is described and its use is illustrated with several examples.     

Automating trade-off analysis of security requirements

A key aspect of engineering secure systems is identifying adequate security requirements to protect critical assets from harm. However, security requirements may compete with other requirements such as cost and usability. For this reason, they may only be satisfied partially and must be traded off against other requirements to achieve “good-enough security”. This paper proposes a novel approach to automate security requirements analysis in order to determine maximum achievable satisfaction level for security requirements and identify trade-offs between security and other requirements. We also propose a pruning algorithm to reduce the search space size in the analysis. We represent security concerns and requirements using asset, threat, and goal models, initially proposed in our previous work. To deal with uncertainty and partial requirements, satisfaction security concerns are quantified by leveraging the notion of composite indicators, which are computed through metric functions based on range normalisation. An SMT solver (Z3) interprets the models and automates the execution of our analyses. We illustrate and evaluate our approach by applying it to a substantive example of a service-based application for exchanging emails.