Mirror‐based reflection in AmbientTalk

This paper introduces a novel mechanism to perform intercession (a form of reflection) in an object‐oriented programming language with the goal of making the language extensible from within itself. The proposed mechanism builds upon a mirror‐based architecture, leading to a reusable reflective application programming interface that cleanly separates interface from implementation details. However, support for intercession has been limited in contemporary mirror‐based architectures. This is due to the fact that mirror‐based architectures only support reflection explicitly triggered by metaprograms, while intercession requires reflection implicitly triggered by the language interpreter. This work reconciles mirrors with intercession in the context of an actor‐based, object‐oriented programming language named AmbientTalk. We describe this language's full reflective architecture, highlighting its novel mirror‐based approach to reflect upon both objects and concurrently executing actors. Subsequently, we apply AmbientTalk's mirror‐based reflection to implement two language features, which crucially depend on intercession, to wit future‐type message passing and leased object references. Copyright © 2008 John Wiley & Sons, Ltd.     

Visual programming with analogical representations: Inspirations from a semiotic analysis of comics

Analogical representations based on pictures of domain objects can be used in visual programming to provide a close mapping between the program and the resulting runtime display, which can make programming easier for children and other users. The use of graphical rewrite rules with before and after pictures is an example of this approach. Graphical rewrite rules have some similarities with comics strips, which also use picture sequences of graphical objects to describe dynamics in a static form. However, the visual language of comics is not used to its full potential in visual programming. We discuss how a semiotic analysis of comics can be used to address some of the limitations of graphical rewrite rules. We use a visual programming system we have designed to illustrate that comic strips can express more general computations and be more intuitive and flexible than traditional graphical rewrites. Our conclusion is that the visual language of comics has a strong potential for increasing the expressiveness and flexibility of visual programming with analogical representations of domain objects, while maintaining a direct mapping between the program representation and the runtime representation.     

Assessment of programming language learning based on peer code review model: Implementation and experience report

The traditional assessment approach, in which one single written examination counts toward a student’s total score, no longer meets new demands of programming language education. Based on a peer code review process model, we developed an online assessment system called EduPCR and used a novel approach to assess the learning of computer programming languages. Using this approach, students peer review programs written by other students, share ideas and make suggestions to achieve an objective of collaborative and interactive learning. Teachers assess and give scores to students based on their performance in writing, reviewing and revising programs and their abidance to a peer code review process. After using this approach in two courses in two consecutive semesters, we observed significant improvements of student learning in various aspects. We also conducted two questionnaire surveys and two interviews. The survey data and the interview report indicated that this assessment approach demonstrates high practical values in assessing student learning outcomes in programming languages. Additionally, this approach leads to several interesting research topics for future research in this field.     

Monaco—A domain-specific language solution for reactive process control programming with hierarchical components

In this paper, we present Monaco – a domain-specific language for developing event-based, reactive process control programs – and its visual interactive programming environment. The main purpose of the language is to bring process control programming closer to domain experts. Important design goals have therefore been to keep the language concise and to allow programs to be written that reflect the perceptions of domain experts. Monaco is similar to Statecharts in its expressive power, but adopts an imperative notation. Moreover, Monaco uses a state-of-the-art component approach with interfaces and polymorphic implementations, and enforces strict hierarchical component architectures that support hierarchical abstraction of control functionality. We present the main design goals, the essential programming elements, the visual interactive programming environment, results from industrial case studies, and a formal definition of the semantics of the reactive behavior of Monaco programs in the form of labeled transition systems.     

Unix tools as visual programming components in a GUI‐builder environment

Development environments based on ActiveX controls and JavaBeans are marketed as ‘visual programming’ platforms; in practice their visual dimension is limited to the design and implementation of an application's graphical user interface (GUI). The availability of sophisticated GUI development environments and visual component development frameworks is now providing viable platforms for implementing visual programming within general‐purpose platforms, i.e. for the specification of non‐GUI program functionality using visual representations. We describe how specially designed reflective components can be used in an industry‐standard visual programming environment to graphically specify sophisticated data transformation pipelines that interact with GUI elements. The components are based on Unix‐style filters repackaged as ActiveX controls. Their visual layout on the development environment canvas is used to specify the connection topology of the resultant pipeline. The process of converting filter‐style programs into visual controls is automated using a domain‐specific language. We demonstrate the approach through the design and the visual implementation of a GUI‐based spell‐checker. Copyright © 2001 John Wiley & Sons, Ltd.     

基于标记语言的并行多核编程方法

提出一种在多核平台上的快速多线程编程模型ThreadXML。该模型通过使用标记语言形式,提高程序的开发效率,支持可视化,增强并行程序设计的移植性。其中,语言模型编译器的实现采用代码模板技术和面向对象技术相结合的方式,能将ThreadXML源代码转换成目前可执行的程序代码,辅助可视化工具采用图元对象和代码模板技术实现。     

COCOVILA – Compiler-Compiler for Visual Languages

A compiler-compiler for visual languages is presented. It has been designed as a framework for building visual programming environments that translate schemas into textual representation as well as into programs representing the deep meaning of schemas. The deep semantics is implemented by applying attribute grammars to schema languages; attribute dependencies are implemented as methods of Java classes. Unlike compiler-compilers of textual languages, a large part of the framework is needed for support of interactive usage of a visual language.     

Generating tools from graph-based specifications

This paper describes an approach for generating graphical, structure-oriented software engineering tools from graph-based specifications. The approach is based on the formal meta modeling of visual languages using graph rewriting systems. Besides the syntactical and semantical rules of the language, these meta models include knowledge from the application domains. This enables the resulting tools to provide the user with high level operations for editing, analysis and execution of models. Tools are constructed by generating source code from the meta model of the visual language, which is written in the very high level programming language PROGRES. The source code is integrated into a framework which is responsible for the invocation of commands and the visualization of graphs. As a case study, a visual language for modeling development processes together with its formal meta model is introduced. The paper shows how a process management tool based on this meta model is generated and reports on our experiences with this approach.     

Structure and software tools of AIDA

AIDA consists of a set of software tools to allow for fast development and easy-to-maintain Medical Information Systems. AIDA supports all aspects of such a system both during development and operation. It contains tools to build and maintain forms for interactive data entry and on-line input validation, a database management system including a data dictionary and a set of run-time routines for database access, and routines for querying the database and output formatting. Unlike an application generator, the user of AIDA may select parts of the tools to fulfill his needs and program other subsystems not developed with AIDA. The AIDA software uses as host language the ANSI-standard programming language MUMPS, an interpreted language embedded in an integrated database and programming environment. This greatly facilitates the portability of AIDA applications. The database facilities supported by AIDA are based on a relational data model. This data model is built on top of the MUMPS database, the so-called global structure. This relational model overcomes the restrictions of the global structure regarding string length. The global structure is especially powerful for sorting purposes. Using MUMPS as a host language allows the user an easy interface between user-defined data validation checks or other user-defined code and the AIDA tools. AIDA has been designed primarily for prototyping and for the construction of Medical Information Systems in a research environment which requires a flexible approach. The prototyping facility of AIDA operates terminal independent and is even to a great extent multi-lingual. Most of these features are table-driven; this allows on-line changes in the use of terminal type and language, but also causes overhead. AIDA has a set of optimizing tools by which it is possible to build a faster, but (of course) less flexible code from these table definitions. By separating the AIDA software in a source and a run-time version, one is able to write implementation-specific code which can be selected and loaded by a special source loader, being part of the AIDA software. This feature is also accessible for maintaining software on different sites and on different installations.     

基于代码结构知识的软件文档语义搜索方法

自然语言文本形式的文档是软件项目的重要组成部分.如何帮助开发者在大量文档中进行高效、准确的信息定位,是软件复用领域中的一个重要研究问题.提出了一种基于代码结构知识的软件文档语义搜索方法.该方法从软件项目的源代码中解析出代码结构图,并以此作为领域特定的知识来帮助机器理解自然语言文本的语义.这一语义信息与信息检索技术相结合,从而实现了对软件文档的语义检索.在StackOverflow问答文档数据集上的实验表明,与多种文本检索方法相比,该方法在平均准确率（mean average precision,简称MAP）上可以取得至少13.77%的提升.     

A Graph-Rewriting Visual Language for Database Programming

Textual database programming languages are computationally complete, but have the disadvantage of giving the user a non-intuitive view of the database information that is being manipulated. The visual languages developed in recent years have allowed naive users access to a direct representation of data, often in a graph form, but have concentrated on user interface rather than complex programming tasks. There is a need for a system which combines the advantages of both these programming methods.We describe an implementation of Spider, an experimental visual database programming language aimed at programmers. It uses a graph-rewriting paradigm as a basis for a fully visual, computationally complete language. The graphs it rewrites represent the schema and instances of a database.The unique graph-rewriting method used by Spider has syntactic and semantic simplicity. Its form of algorithmic expression allows complex computation to be easily represented in short programs. Furthermore, Spider has greater power than normally provided in textual systems, and we show that queries on the schema and associative queries can be performed easily and without requiring any additions to the language.     

Improving App Inventor usability via conversion between blocks and text

We have developed TAIL, a textual programming language isomorphic to the blocks language of MIT App Inventor (AI), and have extended AI with code blocks, a novel mechanism that enables bidirectional conversions between blocks and text fragments. TAIL improves AI׳s usability by facilitating the reading, writing, and sharing of programs, and may also ease the transition from blocks to text programming.     

End-User Visualization and Manipulation of Distributed Aggregate Data

Aggregate visualization and manipulation enables the viewing and interaction of dynamically changing data sets in a graphically meaningful way. However, off-the-shelf applications typically provide only limited ways to view static aggregates and generally do not support manipulation of aggregate data through the resulting visualization. To be fully dynamic, an aggregate visualization should be customizable to suit the individual's needs and should allow end-users to modify the data through direct manipulation. This paper describes a software system that empowers end-users to create interactive aggregate visualizations through a visual language interface. Included are mechanisms for specifying how aggregate data is processed from multiple sources of a distributed application, providing functionality similar to project, select, join, and cross product of relational databases. This approach gives end-users the power to create customized, interactive visualizations of dynamically changing aggregate data without the need for textual programming.     

Embed finite domain constraint programming into Java and some Web‐based applications

Although constraint programming has attracted much attention in logic programming, nowadays the importance to integrate constraints with imperative programming is widely acknowledged. In particular, in artificial intelligence domains, the benefits deriving from merging constraint‐based programming with object‐oriented paradigms seem to be still more attractive because of the lack of ‘pure’ AI languages in supporting structured representations. This work presents the extension of the Java language towards finite domain constraint programming. This extension has been possible thanks to a high‐level approach to low‐level resource management: the sleeper mechanism. As practical results, this paper shows how Java programmers can develop meaningful applications in which finite domain constraints have been extensively used, as in the design of visual, interactive, user‐interface environments in a client–server architecture. Copyright © 1999 John Wiley & Sons, Ltd.     

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.     

Evidence in favor of visual representation for the dataflow paradigm: An experiment testing LabVIEW's comprehensibility

This paper reports an experiment that examined the comprehensibility of the LabVIEW programming representation. LabVIEW is a visual programming language (VPL) based on the dataflow paradigm. The experiment compared LabVIEW to a semantically equivalent textual language using three types of tasks: (1) tracing problems: given code and input values, subjects were asked what output the code would produce if executed. (2) Parallelism problems: given code with several program statements highlighted, subjects were asked about the sequence in which those statements could execute. (3) Debugging problems: given code and its specifications, subjects were asked to find a logic error in the code. The experiment measured the subjects’ time to solve the problems and accuracy of the answers. The subjects were upper-level university students who were intermediate-level programmers with no prior exposure to LabVIEW. Their performances showed differences due to representation for all three task types. Subjects using the textual representation completed the tracing problems significantly faster than subjects using the visual representation. In contrast, subjects using the visual representation were significantly faster for the parallelism problems and significantly more accurate for both the parallelism and debugging problems. These results contribute clear evidence for selected benefits of a visual representation for small-sized code segments, evidence that LabVIEW succeeds in highlighting data dependencies, and evidence that LabVIEW helps programmers to maintain an overview of their code. The authors consider the implications of these results for VPLs more generally.