Design and Implementation of Audio/Video Collaboration System Based on Publish/subscribe Event Middleware

In this paper we present our A/V collaboration system based on our XGSP collaboration framework and NaradaBrokering messaging middleware. Using publish/subscribe event model, this system can provide videoconferencing services to heterogeneous endpoints such as H.323, SIP and Access Grid. This paper discusses the common a/v collaboration model shared by all kinds of A/V conferencing clients and introduces the details about how to implement such a model based on publish/subscribe event middleware

A study of publish/subscribe systems for real-time grid monitoring

Monitoring and controlling a large number of geographically distributed scientific instruments is a challenging task. Some operations on these instruments require real-time (or quasi real-time) response which make it even more difficult. In this paper, we describe the requirements of distributed monitoring for a possible future electrical power grid based on real-time extensions to grid computing. We examine several standards and publish/subscribe middleware candidates, some of which were specially designed and developed for grid monitoring. We analyze their architecture and functionality, and discuss the advantages and disadvantages. We report on a series of tests to measure their real-time performance and scalability

Building capacity in climate change policy analysis and negotiation: methods and technologies

Capacity building is often cited as the reason “we cannot just pour money into developing countries” and why so many development projects fail because their design does not address local conditions. It is therefore a key technical and political concept in international development. Some of the poorest countries in the world are also some of the most vulnerable to the impacts of climate change. Their vulnerability is in part due to a lack of capacity to plan and anticipate the effects of climate change on crops, water resources, urban electricity demand etc. What capacities do these countries lack to deal with climate change? How will they cope? What steps can they take to reduce their vulnerability? This innovative and high-profile research project was part of a larger project (called C3D) and conducted with non-governmental organisations in Senegal, South Africa and Sri Lanka. The research involved several participatory workshops and a questionnaire to all three research centres

Open Access to Resource Management in Multimedia Networks

The paper is dedicated to mechanisms for open access to resource management in the Internet Protocol (IP) multimedia networks. First we present the concept of IP Multimedia Subsystem (IMS) and explain the IMS functional architecture, principles of quality of service management and service control in IMS. Then we describe the idea behind the opening of network interfaces for third parties so that others besides the network operator can create and deploy services. Open Service Access (OSA) and Parlay appear to be the technologies for value-added service delivery in multimedia networks. In the paper we take a closer look to the Parlay/OSA interfaces that allow third party applications to access the resource management functions in IMS. OSA "Connectivity Manager" interfaces and OSA "Policy Management" interfaces are considered. Parlay X Web Services interfaces provide a higher level of abstraction than Parlay/OSA interfaces and gain an amazing amount of support among service developers. We address "Applicationdriven Quality of Service" Parlay X Web Service and "Policy" Parlay X Web Service also

Оптимизация алгоритмов распределения потоков мультимедийных данных между сервером и клиентом в приложениях видеоконференцсвязи

Optimization of working with multimedia resources on purpose reduce transmitted amount of data between users is one of the problems videoconferencing applications. The paper describes algorithms and software, that allows to made optimization of cross-platform videoconferencing application. The main stages of videoconferencing application are: creation and deletion of audio and video streams of data, their transmission from the server to the client and back, creation chains of streams and their search on the server. The above stages are presents in any videoconferencing application and they have to be optimized due to the presence that they contain key processes and the complexity of the architecture of the application. Therefore, in the course of work has been done simplification of the client part of the application and the reorganization of the structure of the server-side application. In transmit-receive mode of data developed application after optimization, compared with the program "Skype" was consuming almost 10 times less RAM and 2 times less CPU.Оптимизация работы с мультимедийными ресурсами с целью сокращения передаваемого объема данных между пользователями является одной из проблем приложений видеоконференцсвязи. В статье описаны алгоритмы и программные средства, позволившие провести оптимизацию разработанного кроссплатформенного приложения видеоконференцсвязи. Основными этапами работы средств видеоконференцсвязи являются: создание и удаление аудио- и видеопотоков данных, их передача от сервера к клиенту и обратно, создание цепочек потоков и их поиск на сервере. Вышеперечисленные этапы присутствуют в любом приложении видеоконференцсвязи и требуют оптимизации в связи с присутствием в них главных процессов и сложностью архитектуры самого приложения. Поэтому в ходе работы было выполнено упрощение клиентской части приложения и реорганизация структуры серверной части приложения. В режиме приема-передачи данных разработанное приложение после проведенной оптимизации по сравнению с программой «Skype» стало потреблять почти в 10 раз меньше оперативной памяти и в 2 раза меньше процессорного времени

The Semantic Grid: A future e-Science infrastructure

e-Science offers a promising vision of how computer and communication technology can support and enhance the scientific process. It does this by enabling scientists to generate, analyse, share and discuss their insights, experiments and results in an effective manner. The underlying computer infrastructure that provides these facilities is commonly referred to as the Grid. At this time, there are a number of grid applications being developed and there is a whole raft of computer technologies that provide fragments of the necessary functionality. However there is currently a major gap between these endeavours and the vision of e-Science in which there is a high degree of easy-to-use and seamless automation and in which there are flexible collaborations and computations on a global scale. To bridge this practice–aspiration divide, this paper presents a research agenda whose aim is to move from the current state of the art in e-Science infrastructure, to the future infrastructure that is needed to support the full richness of the e-Science vision. Here the future e-Science research infrastructure is termed the Semantic Grid (Semantic Grid to Grid is meant to connote a similar relationship to the one that exists between the Semantic Web and the Web). In particular, we present a conceptual architecture for the Semantic Grid. This architecture adopts a service-oriented perspective in which distinct stakeholders in the scientific process, represented as software agents, provide services to one another, under various service level agreements, in various forms of marketplace. We then focus predominantly on the issues concerned with the way that knowledge is acquired and used in such environments since we believe this is the key differentiator between current grid endeavours and those envisioned for the Semantic Grid

A Cloud Infrastructure for Multimedia Conferencing Applications

Conferencing enables the conversational exchange of media between several parties. Conferencing applications are among important enterprise applications nowadays. However, fine grained scalability and elasticity remain quite elusive for multimedia conferencing applications, although they are key to efficiency in the resource usage. Cloud computing is an emerging paradigm for provisioning network, storage, and computing resources on demand using a pay-per-use model. Cloud-based conferencing services can inherent several benefits such as resource usage efficiency, scalability and easy introduction of different types of conferences. This thesis relies on a recently proposed business model for cloud-based conferencing. The model has the following roles: conferencing substrate provider, conferencing infrastructure provider, conferencing platform provider, conferencing service provider, and broker. Conferencing substrates are generally atomic and served as elementary building blocks (e.g. signalling, mixing) of conferencing applications. They can be virtualized and shared among several conferencing applications for resource efficiency purposes. Multiple conferencing substrates provided by different conferencing substrate providers can be combined to build a conferencing service (e.g. a dial-out signalling substrate and an audio mixer substrate can be composed to build a dial-out audio conference service). This thesis focuses on the conferencing infrastructure provider and conferencing substrate provider roles. It proposes a virtualized cloud infrastructure for multimedia conferencing applications. This infrastructure relies on fine grained conferencing substrates (e.g. dial-out signalling, dial-in signalling, audio mixer, video mixer, floor control, etc.) and offers several advantages in addition to fine grained scalability and elasticity (e.g. assembling substrates on the fly to build new conferencing applications). An architecture is proposed to realize the roles of conferencing infrastructure provider, conferencing substrate provider and their interactions. A resource allocation mechanism for conferencing substrates is also proposed. We have also built a prototype with Xen as the virtualization platform and validated the architecture. Performance has also been evaluated

Performance evaluation of information and communications technology infrastructure for smart distribution network applications

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.Current electrical networks require secure, scalable and cost-effective Information and Communications Technology (ICT) solutions to facilitate the novel functionalities required by Smart Grids. Countries around the globe are investigating alternative energy sources to mitigate the current energy crisis and environmental issues experienced by many countries due to global warming, rapid growth of population, inefficient energy management, dwindling fossil fuel resources, etc. Therefore, alternative or renewable energy sources, such as wind, solar, hydro, combined heat and power, etc., are required to mitigate such a crisis and such sources will also need to be integrated in to the power grid in a distributed manner. Such distributed energy sources are mainly connected to the distribution networks and introduce huge challenges to the distribution network operator (DNO). Many of these challenges cannot be dealt with effectively using existing network operation mechanisms therefore the research and development of novel ICT solutions to support smart distribution network operation is required. This research investigated suitable ICT solutions to enable the Smart Grid to tackle these challenges and proposes ICT infrastructure models that can be used for simulation studies in order to investigate cost-effective, scalable and secure solutions for the DNOs. Initially, a Quality of Service (QoS) monitoring test-bed was proposed to evaluate the performance of bandwidth intensive applications, such as smart meter data transmission. Simulation studies for different communication technologies, cellular and Power Line Communication (PLC), were also carried out and the simulation models were verified using experimental test results. Finally, the modelling and analysis of smart metering infrastructure was carried out using simulation and extensive studies were performed to evaluate the data transmission rate performance for different configurations of smart meters and concentrators