Architecture for Cooperative Prefetching in P2P Video-on- Demand System

Most P2P VoD schemes focused on service architectures and overlays optimization without considering segments rarity and the performance of prefetching strategies. As a result, they cannot better support VCRoriented service in heterogeneous environment having clients using free VCR controls. Despite the remarkable popularity in VoD systems, there exist no prior work that studies the performance gap between different prefetching strategies. In this paper, we analyze and understand the performance of different prefetching strategies. Our analytical characterization brings us not only a better understanding of several fundamental tradeoffs in prefetching strategies, but also important insights on the design of P2P VoD system. On the basis of this analysis, we finally proposed a cooperative prefetching strategy called "cooching". In this strategy, the requested segments in VCR interactivities are prefetched into session beforehand using the information collected through gossips. We evaluate our strategy through extensive simulations. The results indicate that the proposed strategy outperforms the existing prefetching mechanisms.Comment: 13 Pages, IJCN

Web Caching and Prefetching with Cyclic Model Analysis of Web Object Sequences

Web caching is the process in which web objects are temporarily stored to reduce bandwidth consumption, server load and latency. Web prefetching is the process of fetching web objects from the server before they are actually requested by the client. Integration of caching and prefetching can be very beneficial as the two techniques can support each other. By implementing this integrated scheme in a client-side proxy, the perceived latency can be reduced for not one but many users. In this paper, we propose a new integrated caching and prefetching policy called the WCP-CMA which makes use of a profit-driven caching policy that takes into account the periodicity and cyclic behaviour of the web access sequences for deriving prefetching rules. Our experimental results have shown a 10%-15% increase in the hit ratios of the cached objects and 5%-10% decrease in delay compared to the existing schem

A Latency-Determining/User Directed Firefox Browser Extension

As the World Wide Web continues to evolve as the preferred choice for information access it is critical that its utility to the user remains. Latency as a result of network congestion, bandwidth availability, server processing delays, embedded objects, and transmission delays and errors can impact the utility of the web browser application. To improve the overall user experience the application needs to not only provide feedback to the end user about the latency of links that are available but to also provide them controls in the retrieval of the web content. This thesis presents a background and related work relating to latency and web optimization techniques to reduce this latency and then introduce an improvement to the ``latency aware" Mozilla Firefox extension which was originally developed by Sterbenz et. al., in 2002. This these describes the architecture and prototype implementation, followed with an analysis of its effectiveness to predict latency and future wor

Durability of Wireless Charging Systems Embedded Into Concrete Pavements for Electric Vehicles

Point clouds are widely used in various applications such as 3D modeling, geospatial analysis, robotics, and more. One of the key advantages of 3D point cloud data is that, unlike other data formats like texture, it is independent of viewing angle, surface type, and parameterization. Since each point in the point cloud is independent of the other, it makes it the most suitable source of data for tasks like object recognition, scene segmentation, and reconstruction. Point clouds are complex and verbose due to the numerous attributes they contain, many of which may not be always necessary for rendering, making retrieving and parsing a heavy task. As Sensors are becoming more precise and popular, effectively streaming, processing, and rendering the data is also becoming more challenging. In a hierarchical continuous LOD system, the previously fetched and rendered data for a region may become unavailable when revisiting it. To address this, we use a non-persistence cache using hash-map which stores the parsed point attributes, which still has some limitations, such as the dataset needing to be refetched and reprocessed if the tab or browser is closed and reopened which can be addressed by persistence caching. On the web, popularly persistence caching involves storing data in server memory, or an intermediate caching server like Redis. This is not suitable for point cloud data where we have to store parsed and processed large point data making point cloud visualization rely only on non-persistence caching. The thesis aims to contribute toward better performance and suitability of point cloud rendering on the web reducing the number of read requests to the remote file to access data.We achieve this with the application of client-side-based LRU Cache and Private File Open Space as a combination of both persistence and non-persistence caching of data. We use a cloud-optimized data format, which is better suited for web and streaming hierarchical data structures. Our focus is to improve rendering performance using WebGPU by reducing access time and minimizing the amount of data loaded in GPU. Preliminary results indicate that our approach significantly improves rendering performance and reduce network request when compared to traditional caching methods using WebGPU

Techniques of data prefetching, replication, and consistency in the Internet

Internet has become a major infrastructure for information sharing in our daily life, and indispensable to critical and large applications in industry, government, business, and education. Internet bandwidth (or the network speed to transfer data) has been dramatically increased, however, the latency time (or the delay to physically access data) has been reduced in a much slower pace. The rich bandwidth and lagging latency can be effectively coped with in Internet systems by three data management techniques: caching, replication, and prefetching. The focus of this dissertation is to address the latency problem in Internet by utilizing the rich bandwidth and large storage capacity for efficiently prefetching data to significantly improve the Web content caching performance, by proposing and implementing scalable data consistency maintenance methods to handle Internet Web address caching in distributed name systems (DNS), and to handle massive data replications in peer-to-peer systems. While the DNS service is critical in Internet, peer-to-peer data sharing is being accepted as an important activity in Internet.;We have made three contributions in developing prefetching techniques. First, we have proposed an efficient data structure for maintaining Web access information, called popularity-based Prediction by Partial Matching (PB-PPM), where data are placed and replaced guided by popularity information of Web accesses, thus only important and useful information is stored. PB-PPM greatly reduces the required storage space, and improves the prediction accuracy. Second, a major weakness in existing Web servers is that prefetching activities are scheduled independently of dynamically changing server workloads. Without a proper control and coordination between the two kinds of activities, prefetching can negatively affect the Web services and degrade the Web access performance. to address this problem, we have developed a queuing model to characterize the interactions. Guided by the model, we have designed a coordination scheme that dynamically adjusts the prefetching aggressiveness in Web Servers. This scheme not only prevents the Web servers from being overloaded, but it can also minimize the average server response time. Finally, we have proposed a scheme that effectively coordinates the sharing of access information for both proxy and Web servers. With the support of this scheme, the accuracy of prefetching decisions is significantly improved.;Regarding data consistency support for Internet caching and data replications, we have conducted three significant studies. First, we have developed a consistency support technique to maintain the data consistency among the replicas in structured P2P networks. Based on Pastry, an existing and popular P2P system, we have implemented this scheme, and show that it can effectively maintain consistency while prevent hot-spot and node-failure problems. Second, we have designed and implemented a DNS cache update protocol, called DNScup, to provide strong consistency for domain/IP mappings. Finally, we have developed a dynamic lease scheme to timely update the replicas in Internet

A taxonomy of web prediction algorithms

Web prefetching techniques are an attractive solution to reduce the user-perceived latency. These techniques are driven by a prediction engine or algorithm that guesses following actions of web users. A large amount of prediction algorithms has been proposed since the first prefetching approach was published, although it is only over the last two or three years when they have begun to be successfully implemented in commercial products. These algorithms can be implemented in any element of the web architecture and can use a wide variety of information as input. This affects their structure, data system, computational resources and accuracy. The knowledge of the input information and the understanding of how it can be handled to make predictions can help to improve the design of current prediction engines, and consequently prefetching techniques. This paper analyzes fifty of the most relevant algorithms proposed along 15 years of prefetching research and proposes a taxonomy where the algorithms are classified according to the input data they use. For each group, the main advantages and shortcomings are highlighted. © 2012 Elsevier Ltd. All rights reserved.This work has been partially supported by Spanish Ministry of Science and Innovation under Grant TIN2009-08201, Generalitat Valenciana under Grant GV/2011/002 and Universitat Politecnica de Valencia under Grant PAID-06-10/2424.Domenech, J.; De La Ossa Perez, BA.; Sahuquillo Borrás, J.; Gil Salinas, JA.; Pont Sanjuan, A. (2012). A taxonomy of web prediction algorithms. Expert Systems with Applications. 39(9):8496-8502. https://doi.org/10.1016/j.eswa.2012.01.140S8496850239

Quality of Service Issues in Internet Web Services

Editorial special section on "Quality of Service Issues in Internet Web Services