Adaptive real-time predictive collaborative content discovery and retrieval in mobile disconnection prone networks

Emerging mobile environments motivate the need for the development of new distributed technologies which are able to support dynamic peer to peer content sharing, decrease high operating costs, and handle intermittent disconnections. In this paper, we investigate complex challenges related to the mobile disconnection tolerant discovery of content that may be stored in mobile devices and its delivery to the requesting nodes in mobile resource-constrained heterogeneous environments. We propose a new adaptive real-time predictive multi-layer caching and forwarding approach, CafRepCache, which is collaborative, resource, latency, and content aware. CafRepCache comprises multiple multi-layer complementary real-time distributed predictive heuristics which allow it to respond and adapt to time-varying network topology, dynamically changing resources, and workloads while managing complex dynamic tradeoffs between them in real time. We extensively evaluate our work against three competitive protocols across a range of metrics over three heterogeneous real-world mobility traces in the face of vastly different workloads and content popularity patterns. We show that CafRepCache consistently maintains higher cache availability, efficiency and success ratios while keeping lower delays, packet loss rates, and caching footprint compared to the three competing protocols across three traces when dynamically varying content popularity and dynamic mobility of content publishers and subscribers. We also show that the computational cost and network overheads of CafRepCache are only marginally increased compared with the other competing protocols

Developing Peer-To-Peer Web Applications

As the virtual world grows more complex, finding a standard way for storing data becomes increasingly important. Ideally, each data item would be brought into the computer system only once. References for data items need to be cryptographically verifiable, so the data can maintain its identity while being passed around. This way there will be only one copy of the users family photo album, while the user can use multiple tools to show or manipulate the album. Copies of users data could be stored on some of his family members computer, some of his computers, but also at some online services which he uses. When all actors operate over one replicated copy of the data, the system automatically avoids a single point of failure. Thus the data will not disappear with one computer breaking, or one service provider going out of business. One shared copy also makes it possible to delete a piece of data from all systems at once, on users request. In our research we tried to find a model that would make data manageable to users, and make it possible to have the same data stored at various locations. We studied three systems, Persona, Freenet, and GNUnet, that suggest different models for protecting user data. The main application areas of the systems studied include securing online social networks, providing anonymous web, and preventing censorship in file-sharing. Each of the systems studied store user data on machines belonging to third parties. The systems differ in measures they take to protect their users from data loss, forged information, censorship, and being monitored. All of the systems use cryptography to secure names used for the content, and to protect the data from outsiders. Based on the gained knowledge, we built a prototype platform called Peerscape, which stores user data in a synchronized, protected database. Data items themselves are protected with cryptography against forgery, but not encrypted as the focus has been disseminating the data directly among family and friends instead of letting third parties store the information. We turned the synchronizing database into peer-to-peer web by revealing its contents through an integrated http server. The REST-like http API supports development of applications in javascript. To evaluate the platform’s suitability for application development we wrote some simple applications, including a public chat room, bittorrent site, and a flower growing game. During our early tests we came to the conclusion that using the platform for simple applications works well. As web standards develop further, writing applications for the platform should become easier. Any system this complex will have its problems, and we are not expecting our platform to replace the existing web, but are fairly impressed with the results and consider our work important from the perspective of managing user data

Energy-efficient cloud computing application solutions and architectures

Environmental issues are receiving unprecedented attention from business and governments around the world. As concern for greenhouse, climate change and sustainability continue to grow; businesses are grappling with improving their environmental impacts while remaining profitable. Many businesses have discovered that Green IT initiatives and strategies can reform the organization, comply with laws and regulations, enhance the public appearance of the organization, save energy cost, and improving their environmental impacts. One of these Green IT initiatives is migrating or building the business applications in the cloud. Cloud computing is a highly scalable and cost-effective infrastructure for running enterprise and web applications. As a result, building enterprise systems on cloud computing platform is increasing significantly today. However, cloud computing is not inherently proposing energy efficiency solutions for these businesses. In this thesis, a concept has been developed to support organizations choosing suitable energy-efficient cloud architecture while moving their application to the cloud or building new cloud applications. Thus, the concept focuses on how to employ the cloud computing technology as an energy efficient solution from the application perspective. The main idea applied in the concept is identifying architectures for cloud applications depending on the inherent properties of cloud computing such as virtualization and the elasticity that can make them green potential, and identifying correlations between these architectures with already identified business process patterns used in green business process design. Alongside with these correlations, the application has been decomposed into basic technical and business attributes that can describe the application. The relations between these attributes and the cloud architectures have been defined. The relations between the different components the application attributes, application architectures, and the green patterns can lead to not only the energy-efficient cloud architecture for the business application, but also to the architectures that can achieve the organization technical and business requirements. Prototypically, a recommender system has been implemented that supports the identification of suitable energy-efficient cloud application architectures in addition to the cloud migration decision

Understanding the performance of interactive applications

Many if not most computer systems are used by human users. The performance of such interactive systems ultimately affects those users. Thus, when measuring, understanding, and improving system performance, it makes sense to consider the human user's perspective. Essentially, the performance of interactive applications is determined by the perceptible lag in handling user requests. So, when characterizing the runtime of an interactive application we need a new approach that focuses on the perceptible lags rather than on overall and general performance characteristics. Such a new characterization approach should enable a new way to profile and improve the performance of interactive applications. Imagine a way that would seek out these perceptible lags and then investigate the causes of these lags. Performance analysts could simply optimize responsible parts of the software, thus eliminating perceptible lag for interactive applications. Unfortunately, existing profiling approaches either incur significant overhead that makes them impractical for an interactive scenario, or they lack the ability to provide insight into the causes of long latencies. An effective approach for interactive applications has to fulfill several requirements such as an accurate view of the causes of performance problems and insignificant perturbation of the interactive application. We propose a new profiling approach that helps developers to understand and improve the perceptible performance of interactive applications and satisfies the above needs

ASCI visualization tool evaluation, Version 2.0

The charter of the ASCI Visualization Common Tools subgroup was to investigate and evaluate 3D scientific visualization tools. As part of that effort, a Tri-Lab evaluation effort was launched in February of 1996. The first step was to agree on a thoroughly documented list of 32 features against which all tool candidates would be evaluated. These evaluation criteria were both gleaned from a user survey and determined from informed extrapolation into the future, particularly as concerns the 3D nature and extremely large size of ASCI data sets. The second step was to winnow a field of 41 candidate tools down to 11. The selection principle was to be as inclusive as practical, retaining every tool that seemed to hold any promise of fulfilling all of ASCI`s visualization needs. These 11 tools were then closely investigated by volunteer evaluators distributed across LANL, LLNL, and SNL. This report contains the results of those evaluations, as well as a discussion of the evaluation philosophy and criteria

Quantum Portal

Este relatório enquadra-se no curso de Mestrado em Engenharia Informática - Computação Móvel da Escola de Tecnologia e Gestão do Instituto Politécnico de Leiria. O objetivo deste relatório é descrever todo o processo em relação ao estágio de 9 meses que foi realizado na empresa Domatica, bem como o trabalho que foi desenvolvido durante o estágio. Este relatório apresenta informações sobre o local do estágio, o trabalho desenvolvido durante o período de estágio e as conclusões extraídas após a conclusão do estágio. Todo o trabalho realizado foi dedicado ao portal Quantum node. Quantum Node Portal funciona como um Portal de Gestão de Informação e Dispositivos. Ele fornece aos clientes instalações como monitorar nós que estão localizados em diferentes locais. O nosso portal de projetos lida com informação sobre os Quantum Nodes dos vários clientes. A informação inclui o status (on-line / off-line), a localização, a visão dos detalhes dos nós, para reivindicar os nós pelo processo de autenticação e também o gerenciamento dos nós e contas de usuários, armazenando a informação atual do nó atualizada pelos clientes, focando principalmente na apresentação de dados visuais sob a forma de tabelas e gráficos e fornece segurança para o Portal Quantum

Big Data Security (Volume 3)

After a short description of the key concepts of big data the book explores on the secrecy and security threats posed especially by cloud based data storage. It delivers conceptual frameworks and models along with case studies of recent technology