2,467 research outputs found

    Digital libraries on an iPod: Beyond the client-server model

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    This paper describes an experimental system that enhanced an iPod with digital library capabilities. Using the open source digital library software Greenstone as a base, this paper more specifically maps out the technical steps necessary to achieve this, along with an account of our subsequent experimentation. This included command-line usage of Greenstone's basic runtime system on the device, augmenting the iPod’s main interactive menu-driven application to include searching and hierarchical browsing of digital library collections stored locally, and a selection of "launcher" applications for target documents such as text files, images and audio. Media rich applications for digital stories and collaging were also developed. We also configured the iPod to run as a web server to provide digital library content to others over a network, effectively turning the traditional mobile client-server upsidedown

    Revista Economica

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    Dynamic Firewall Configuration Using Mobile Agents

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    The nearly omnipresence ofthe Internet and the steady increase ofwireless computing and mobile devices require highly dynamic adaptable distributed system architectures. Building such architectures needs a combination ofkey concepts from component technology and distributed systems. Mobile agents provide this combination. We use mobile agents as the building blocks ofacomponent-based system for remote supervision and control of both hard- and software in a distributed environment. In this paper we concentrate on the configuration ofindividual components and component relationships in our system. We identify requirements for remote configuration ofagent-based component systems and discuss architectural and user interface related issues ofour approaches. We use acode-on-demand approach for supporting elaborate user interfaces. We use a generative approach based on enhanced meta-information for reducing development effort. The presented approaches are applicable for remote configuration of component-based systems in general and consider additional requirements imposed through the use of mobile agenttechnology

    Using a Communication Model to Collect Measurement Data through Mobile Devices

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    Wireless systems and services have undergone remarkable development since the first mobile phone system was introduced in the early 1980s. The use of sensors in an Ambient Intelligence approach is a great solution in a medical environment. We define a communication architecture to facilitate the information transfer between all connected devices. This model is based in layers to allow the collection of measurement data to be used in our framework monitoring architecture. An overlay-based solution is built between network elements in order to provide an efficient and highly functional communication platform that allows the connection of a wide variety of devices and technologies, and serves also to perform additional functions such as the possibility to perform some processing in the network that may help to improve overall performance.Wireless systems and services have undergone remarkable development since the first mobile phone system was introduced in the early 1980s. The use of sensors in an Ambient Intelligence approach is a great solution in a medical environment. We define a communication architecture to facilitate the information transfer between all connected devices. This model is based in layers to allow the collection of measurement data to be used in our framework monitoring architecture. An overlay-based solution is built between network elements in order to provide an efficient and highly functional communication platform that allows the connection of a wide variety of devices and technologies, and serves also to perform additional functions such as the possibility to perform some processing in the network that may help to improve overall performance

    Using a Communication Model to Collect Measurement Data through Mobile Devices

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    Wireless systems and services have undergone remarkable development since the first mobile phone system was introduced in the early 1980s. The use of sensors in an Ambient Intelligence approach is a great solution in a medical environment. We define a communication architecture to facilitate the information transfer between all connected devices. This model is based in layers to allow the collection of measurement data to be used in our framework monitoring architecture. An overlay-based solution is built between network elements in order to provide an efficient and highly functional communication platform that allows the connection of a wide variety of devices and technologies, and serves also to perform additional functions such as the possibility to perform some processing in the network that may help to improve overall performance.Wireless systems and services have undergone remarkable development since the first mobile phone system was introduced in the early 1980s. The use of sensors in an Ambient Intelligence approach is a great solution in a medical environment. We define a communication architecture to facilitate the information transfer between all connected devices. This model is based in layers to allow the collection of measurement data to be used in our framework monitoring architecture. An overlay-based solution is built between network elements in order to provide an efficient and highly functional communication platform that allows the connection of a wide variety of devices and technologies, and serves also to perform additional functions such as the possibility to perform some processing in the network that may help to improve overall performance

    Building distributed sensor network applications using BIP

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    International audienceThe exponential increase in the demands for the deployment of large-scale sensor networks, makes the efficient development of functional applications necessary. Nevertheless, the existence of scarce resources and the derived application complexity, impose significant constraints and requires high design expertise. Consequently, the probability of discovering design errors, once the application is implemented, is considerably high. To address these issues, there is a need for the availability of early-stage validation, performance evaluation and rapid prototyping techniques at design time. In this paper we present a novel approach for the co-design of mixed software/hardware applications for distributed sensor network systems. This approach uses BIP, a formal framework facilitating modeling, analysis and implementation of real-time embedded, heterogeneous systems. Our approach is illustrated through the modeling and deployment of a Wireless Multimedia Sensor Network (WMSN) application. We emphasize on its merits, notably validation of functional and non-functional requirements through statistical model-checking and automatic code generation for sensor network platforms

    End-to-End Simulation of 5G mmWave Networks

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    Due to its potential for multi-gigabit and low latency wireless links, millimeter wave (mmWave) technology is expected to play a central role in 5th generation cellular systems. While there has been considerable progress in understanding the mmWave physical layer, innovations will be required at all layers of the protocol stack, in both the access and the core network. Discrete-event network simulation is essential for end-to-end, cross-layer research and development. This paper provides a tutorial on a recently developed full-stack mmWave module integrated into the widely used open-source ns--3 simulator. The module includes a number of detailed statistical channel models as well as the ability to incorporate real measurements or ray-tracing data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and highly customizable, making it easy to integrate algorithms or compare Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example. The module is interfaced with the core network of the ns--3 Long Term Evolution (LTE) module for full-stack simulations of end-to-end connectivity, and advanced architectural features, such as dual-connectivity, are also available. To facilitate the understanding of the module, and verify its correct functioning, we provide several examples that show the performance of the custom mmWave stack as well as custom congestion control algorithms designed specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and Tutorials (revised Jan. 2018

    Distributed control in virtualized networks

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    The increasing number of the Internet connected devices requires novel solutions to control the next generation network resources. The cooperation between the Software Defined Network (SDN) and the Network Function Virtualization (NFV) seems to be a promising technology paradigm. The bottleneck of current SDN/NFV implementations is the use of a centralized controller. In this paper, different scenarios to identify the pro and cons of a distributed control-plane were investigated. We implemented a prototypal framework to benchmark different centralized and distributed approaches. The test results have been critically analyzed and related considerations and recommendations have been reported. The outcome of our research influenced the control plane design of the following European R&D projects: PLATINO, FI-WARE and T-NOVA
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