Distributed prototyping from validated specifications

We present vpl2cxx, a translator that automatically generates efficient, fully distributed C++ code from high-level system models specified in the mathematically well-founded VPL design language. As the Concurrency Workbench of the New Century (CWB-NC) verification tool includes a front-end for VPL, designers may use the full range of automatic verification and simulation checks provided by this tool on their VPL system designs before invoking the translator, thereby generating distributed prototypes from validated specifications. Besides being fully distributed, the code generated by vpl2cxx is highly readable and portable to a host of execution environments and real-time operating systems (RTOSes). This is achieved by encapsulating all generated code dealing with low-level interprocess communication issues in a library for synchronous communication, which in turn is built upon the adaptive communication environment (ACE) client-server network programming interface. Finally, example applications show that the performance of the generated code is very good, especially for prototyping purposes. We discuss two such examples, including the RETHER real-time Ethernet protocol for voice and video applications.     

Supporting interactive collaboration on the Web with CORK

The World Wide Web has served as a medium for collaboration since its inception. Web-based collaboration has, however, been dominated by systems supporting asynchronous activities such as sharing documents and participating in discussion forums. Supporting interactive, synchronous collaboration on the Web has proven much more challenging. In this paper we describe three of the challenges encountered in the context of supporting network-based collaboration among middle and high school science students: integrating synchronous and asynchronous modes of interaction, minimizing consumption of bandwidth, and adapting non-collaborative software components for collaborative use. We then present the Content Object Replication Kit, a toolkit for building interactive Java-based collaborative systems for use on the Web.     

Rapid prototyping of an ATM programmable associative operator

In this paper, we describe a semi-automatic method for designing a programmable architecture related to high speed communication protocols. A case study of associative based architecture of high speed communication system is presented with a validation environment. The environment provides an interesting estimation using XILINX prototyping board including memories (content addressable memory, CAM, RAM, DPRAM). In our approach, we try to perform a rapid prototyping of such architecture and allow the designer to interact easily in order to customize the architecture according to application requirements. This method of validation provides important benefits in hardware prototyping: better validation environment and reduced time to give a real estimation for a large variety of applications.     

State-centric programming for sensor-actuator network systems

Distributed embedded systems such as wireless sensor and actuator networks require new programming models and software tools to support the rapid design and prototyping of sensing and control applications. Unlike centralized platforms and Web-based distributed systems, these distributed sensor-actuator network (DSAN) systems are characterized by a massive number of potentially failing nodes, limited energy and bandwidth resources, and the need to rapidly respond to sensor input. We describe a state-centric, agent-based design methodology to mediate between a system developer's mental model of physical phenomena and the distributed execution of DSAN applications. Building on the ideas of data-centric networking, sensor databases, and proximity-based group formation, we introduce the notion of collaboration groups, which abstracts common patterns in application-specific communication and resource allocation. Using a distributed tracking application with sensor networks, we'll demonstrate how state-centric programming can raise the abstraction level for application developers.     

An ECA object service to support active distributed objects

Existing Object Management Group (OMG) standards (such as the Common Object Request Broker Architecture specification) provide specific details on how to model distributed objects through the use of an object request broker. However, the specification provided by OMG is not sufficient. For example, it does not specify how active, distributed objects can perform certain functions in response to certain events. It also does not provide any details on how to implement an object service to support active, distributed objects. Such an object service can provide facilities for applications to define events and rules. In view of this, this paper identifies, explores, and provides an approach to model applications as active, distributed objects. The research specifically involves the design, development, and experimental demonstration of an object service based on an active, distributed object model. This object service allows applications to define events and rules. When an event occurs, the object service locates the rule objects and triggers them. It also provides transparency for the objects which generate events. To provide a specific context for the approach, an object service using the specifications provided by the OMG is designed and implemented. The class of application environments for which this approach is suitable and useful includes time-dependent applications and systems that require some form of action such as medical and geographic information systems, distributed work-flow management, distributed expert systems, and computer-integrated manufacturing.     

A multimedia-enhanced collaborative learning environment

Abstract The proliferation of the Internet has brought about the notion of online virtual communities. One enabling technology for online communities is multiuser environments such as Multi-User Dimensions (MUDs) and Object-Oriented MUDS (MOOs). These text-based collaborative learning environments have recently have been integrated with the World Wide Web, thus harnessing the graphics and multimedia-rich environments available therein. Learners can directly experience, manipulate, and create objects in their rich multimedia form. MUDs and MOOs are augmented with synchronous collaboration technology that provided simultaneous control and viewing of shared documents and applications. In this paper, we describe a multimedia-enhanced MOO system called SpaceALIVE! and our experiences from a pilot project involving Singapore students who use SpaceALIVE! as a collaborative learning environment are reported.     

A Dynamic Light-Weight Group Service

The virtual synchrony model for group communication is a powerful paradigm for building distributed applications. Implementations of virtual synchrony usually use failure detectors and failure recovery protocols. In applications that require a large number of groups, significant performance gains can be attained if these groups share the resources required to provide virtual synchrony. A service that maps multiple user groups onto a small number of instances of a virtually synchronous implementation is called a light-weight group service. This paper describes a new design for the light-weight group protocols that enables such service to function transparently. We discuss how these protocols can be applied in dynamic environments, where group mappings cannot be defined a priori and may change over time. We show that it is possible to establish mappings that promote resource sharing and, at the same time, minimize interference. These mappings can be established in an automated manner, using heuristics applied locally at each node. Experiments using an implementation in the Horus system show that significant performance improvements can be achieved with this approach.     

Real-time image processing on a custom computing platform

The authors explore the utility of custom computing machinery for accelerating the development, testing, and prototyping of a diverse set of image processing applications. We chose an experimental custom computing platform called Splash-2 to investigate this approach to prototyping real time image processing designs. Custom computing platforms are emerging as a class of computers that can provide near application specific computational performance. We developed a real time image processing system called VTSplash, based on the Splash-2 general-purpose platform. Splash-2 is an attached processor featuring programmable processing elements (PEs) and communication paths. The Splash-2 system uses arrays of RAM based field programmable gate arrays (FPGAs), crossbar networks, and distributed memory to accomplish the needed flexibility and performance tasks. Such platforms let designers customize specific operations for function and size, and data paths for individual applications     

Promondia: a Java-based framework for real-time group communication in the Web

The World Wide Web has evolved from a distributed hypertext system to a platform-independent graphical user interface that integrates many network services. So far, its technology has restricted it mainly to applications for information retrieval.As networks become ubiquitious and more and more users have a permanent connection, there is an increasing demand for other network services, such as real-time data feeds, group communication, and teleconferencing. So far, these services have been provided by various proprietary software systems, which were hard to set up and use, and thus not very successful.Integrating real-time group communication services into the World Wide Web is a natural way to make them more accessible and will take the Web a step further on its way to becoming the universal network application.In this paper, we describe functionalities required for these services and present an implementation based on Sun Microsystem's Java² programming language. We focus on the high-level functionalities and abstractions, but also describe an object-oriented programming model for group communication systems.     

Language engineering techniques for the development of e-learning applications

In this paper we propose the use of language engineering techniques to improve and systematize the development of e-learning applications. E-learning specifications usually rely on domain-specific languages that describe different aspects of such final e-learning applications. This fact makes it natural to adopt well-established language engineering principles during the construction of these applications. These principles promote the specification of the structure and the runtime behavior of the domain-specific languages as the central part of the development process. This specification can be used to drive different activities: rapid prototyping, provision of authoring notations and tools, automatic model checking of properties, importation/exportation from/to standards, and deployment of running applications. This language engineering concept also promotes active collaboration between instructors (the users of the languages) and developers (the designers and implementers) throughout the development process. In this paper we describe this language-driven approach to the construction of e-learning applications and we illustrate all its aspects using a learning flow sequencing language as a case study.     

Towards a communication model applied to the interface design process

The design of computational artifacts involves many communication acts occurring through different channels; usability tests, for example, have been used as a main communication channel between designers and users. Other channels used during the design process include requirement analysis, scenario construction, prototyping, etc. This work takes the Westley and MacLehan communication model and projects it into the context of interactive artifact design, resulting in a model of fractal nature. Some channels already present during the design process fit in well with the model we are proposing. It also reveals that other channels have not been explored in the global process of communication. Thus, we show how a semiotic-based analysis can unify techniques, methods and tools that support design, as well as make explicit the necessary interactions among designers, users and computers through different channels.     

学习对象元数据在远程教育有效利用研究

随着远程教育的不断发展,如何进行信息资源共享已经成远程教育发展中迫切需要解决的重要任务.在对远程教育中学习对象元数据应用和关键技术分析的基础上,研究在远程教育信息资源共享中如何有效利用学习对象元数据.     

Adapting paper prototyping for designing user interfaces for multiple display environments

A multiple display environment (MDE) networks personal and shared devices to form a virtual workspace, and designers are just beginning to grapple with the challenges of developing interfaces tailored for these environments. To develop effective interfaces for MDEs, designers must employ methods that allow them to rapidly generate and test alternative designs early in the design process. Paper prototyping offers one promising method, but needs to be adapted to effectively simulate the use of multiple displays and allow testing with groups of users. In this paper, we share experiences from two projects in which paper prototyping was utilized to explore interfaces for MDEs. We identify problems encountered when applying the traditional method, describe how these problems were overcome, and distill our experiences into recommendations that others can draw upon. By following our recommendations, designers need only make minor modifications to the existing method to better realize benefits of paper prototyping for MDEs.     

基于多维数据建模的一体化平台

基于快速原型开发思想,设计并实现了一个一体化的多维数据建模平台,该平台为OLAP应用系统设计人员提供了一个快速构建原型系统的支撑环境,采用图示化的方法描述了用户需求,经过简单的操作,可以演示对应的分析结果,便于用户修正与确认,并为系统设计人员提供了一个导向,加快了系统的开发速度。     

Rapid prototyping for DSP systems with multiprocessors

The authors describe the hardware and software of a system for prototyping digital-signal-processing applications by using commercially available digital-signal processors linked to form multiprocessors. The graphical programming environment makes it easier to program, compile, debug, and test DSP algorithms. The system reduces the cost of application prototyping, making it a feasible step at early design stages. To demonstrate the advantages of their approach, the authors explain how they prototyped a digital audio broadcast system. The complexities encountered highlight the limitations of the system     

Toward a cooperative programming framework for context-aware applications

OPEN is an ontology-based programming framework for rapid prototyping, sharing, and personalization of context-aware applications. Unlike previous systems that provide programming support for single group of users, OPEN provides different programming support for users with diverse technical skills. According to the programming requirements of different users, several cooperation patterns are identified, and the mechanisms to facilitate resource sharing and reuse are built into the framework. Three corresponding programming modes are elaborated by showing how a context-aware game has been developed with the support of the OPEN framework, and the usability of our system is validated through an initial user study.     

Supporting rapid design and evaluation of pervasive applications: challenges and solutions

Along with the improvement of the key technologies for pervasive computing, the design of applications itself has emerged as a notable research area. A design should decide which features go into the application of supporting its context-awareness and ascertaining how well those features add value for users with an acceptable user experience. This paper initially identifies the challenges in designing and evaluating pervasive applications. It then presents a condensed survey of prototyping techniques and existing toolkits with the aim of understanding how the design issues have been addressed by research prototypes. At the end, we describe various open issues with suggestions of possible ways to extend the capabilities of current prototyping toolkits.     

Multicast issues for collaborative virtual environments

Multicast networking lets designers use new communication patterns in computer graphics applications. This article introduces multicasting, explains how it differs from more traditional networking, and describes multicasting issues for the application designer