Web Caching Research Articles

공개 키 기반의 계층 구조를 갖는 디지털콘텐트 분배 시스템의 설계

Generally, as for the multimedia high quality contents, an illegality facsimile is possible without a damage of a quality. Also a distribution of contents duplicated illegality in an Internet is giving a great economic loss to digital contents provider. Therefore, a study for security and efficient distribution of digital contents is required. The most important issues in a design of digital contents distribution system are a user convenience, an execution speed and a security. In this study, we designed digital contents distribution system that used a web caching technology and an encryption/decryption technique on hierarchical structure. The proposed system was the digital contents distribution system that improved a security and execution speed, a convenience of a user. Also it verified performance superiority of a proposed system by an examination.

Web caching: A way to improve web QoS

As the Internet and World Wide Web grow at a fast pace, it is essential that the Web's performance should keep up with increased demand and expectations. Web Caching technology has been widely accepted as one of the effective approaches to alleviating Web traffic and increase the Web Quality of Service (QoS). This paper provides an up-to-date survey of the rapidly expanding Web Caching literature. It discusses the state-of-the-art web caching schemes and techniques, with emphasis on the recent developments in Web Caching technology such as the differentiated Web services, heterogeneous caching network structures, and dynamic content caching.

Modeling TCP performance with proxies

This paper investigates TCP dynamics and performance over proxies that shorten the TCP feedback loop by segmenting the end-to-end connection. Such proxies are often used to improve the TCP performance, e.g. a splitting/spoofing proxy in satellite communication, and more commonly, a web cache. Through analysis, we attempt to develop a basic understanding of the properties of TCP dynamics when such proxies are used, and further obtain design principles of systems involving such proxies. We present simple models capturing some features of the proxy performance in both the lossless and lossy scenarios. Due to the complexity involved, detailed analysis is only available in the lossless scenario, and our discussion in the lossy scenario is largely limited to steady-state behavior. Nevertheless we are able to obtain useful insight. We identify conditions under which using a proxy provides significant or marginal performance gain by investigating factors including initial window size, congestion level of the proxy, and the level of asymmetry between the segments segregated by the proxy. We also discuss how these conditions affect the deployment and provisioning of such systems.

Cache Satellite Distribution Systems: Modeling, Analysis, and Efficient Operation

Web caches have become an integral component contributing to the improvement of the performance observed by Web clients. Cache satellite distribution systems (CSDSs) have emerged as a technology for feeding the caches with the information clients are expected to request, ahead of time. In such a system, the participating proxies periodically report to a central station about requests received from their clients. The central station selects a collection of Web documents, which are "pushed" via a satellite broadcast to the participating proxies, so that upon a future local request for the documents, they will already reside in the local cache, and will not need to be fetched from the terrestrial network. In this paper, our aim is addressing the issues of how to operate the CSDS, how to design it, and how to estimate its effect. Questions of interest are: 1) what Web documents should be transmitted by the central station and 2) what is the benefit of adding a particular proxy into a CSDS? We offer a model for CSDS that accounts for the request streams addressed to the proxies and which captures the intricate interaction between the proxy caches. Unlike models that are based only on the access frequency of the various documents, this model captures both their frequency and their locality of reference. We provide an analysis that is based on the stochastic properties of the traffic streams that can be derived from HTTP logs, examine it on real traffic, and demonstrate its applicability in selecting a set of proxies into a CSDS.

A shared cache solution for the home Internet gateway

With the advent of multiple PCs and smart appliances into the modern houses, home networking is becoming increasingly important. Caching at the home Internet gateway is an effective way to maximize the performance of home networking. In this paper, we present an efficient caching scheme that allows the sharing of caches among nearby home Internet gateways. Our new scheme reduces the duplicated copies of the same data items in total shared caches. It also reduces the message overhead of existing cache sharing schemes significantly. Prototype implementation and trace-driven simulations with actual Internet access traces show that the proposed cache sharing scheme outperforms the two well-known Web cache sharing schemes, the Internet cache protocol (ICP) and the cache array routing protocol (CARP) in terms of various performance measures.

상호참조시간을 고려한 단기간 임시지역성 측정

Temporal locality of Web server references is one of the important characteristics to be considered in the design of a Web caching strategy, and it is important to measure the temporal locality exactly. Various methods to estimate the temporal locality have been proposed, however, Web server designers have still troubles in its measurement by using the tools that don`t reflect the interarrival time of document requests. In this paper, we propose a measurement tool for short-term temporal locality based on request interarrival time, and discuss the simulation results based on the flares from NLANR and NASA Web sites. The results show that the proposed tool estimates the short-term temporal locality more exactly than that based on a stack.

On Expiration-Based Hierarchical Caching Systems

Caching is an important means to scale up the growth of the Internet. Weak consistency is a major approach used in Web caching and has been deployed in various forms. The paper investigates some fundamental properties and performance issues associated with an expiration-based caching system. We focus on a hierarchical caching system based on the time-to-live expiration mechanism and present a basic model for such system. By analyzing the intrinsic timing behavior of the basic model, we derive important performance metrics from the perspectives of the caching system and end users, respectively. Based on the results for the basic model, we introduce threshold-based and randomization-based techniques to enhance and generalize the basic model further. Our results offer some important insights into a hierarchical caching system based on the weak consistency paradigm.

The dark side of the Web

With the advent of large-scale, wide-area networking testbeds, researchers can deploy long-running services that interact with other resources on the Web. While such interaction can easily attract clients and traffic, our experience suggests that projects accepting outside input and interacting with outside resources must carefully consider the avenues for abuse of such services. The CoDeeN Content Distribution Network, deployed on PlanetLab, uses a network of caching Web proxy servers to intelligently distribute and cache requests from a potentially large client population. Due to CoDeeN's non-commerical nature, content is not pushed/advertised by content providers, but instead is pulled by clients who have configured their browsers to use CoDeeN.In effect, CoDeeN is one of the largest "open" proxy networks in the world, and therefore draws unwanted attention from malicious users. This paper discusses our experiences with undersirable traffic on CoDeeN, the mechanisms we developed to curtail it, and the future directions for such work. We believe that this work provides a safe alternative to open proxies and will encourage others to deploy similar systems. Some of the security mechanisms we are developing are suitable for ISPs to deploy on their own networks to detect misbehaving customers before problems arise. Finally, other research projects that allow "open" access to Web resources may face similar situations, and may be able to adopt similar mechanisms.

객체 참조 특성 기반의 분할된 영역 웹 캐시 대체 기법

일반적으로 웹 기반 시스템의 성능을 높이기 위하여 웹 캐시를 사용하며, 대체 기법은 웹 캐시의 성능에 큰 영향을 미친다. 웹 캐시를 위한 대체 기법은 메모리 영역의 대체 기법과는 다르게, 대체되는 단위가 웹 객체이다. 또한 웹 객체는 사용자 참조 특성의 편차가 매우 크다. 따라서 웹 캐시론 위한 대체 기법은 이러한 웹 객체의 특성을 충분히 반영할 수 있어야한다. 하지만 기존의 기법에서는 이러한 특성을 충분히 반영하고 있지 못하다. 본 연구의 주된 관점은 참조특성 분석, 객체적중률의 향상, 응답시간의 개선이다. 이를 위해 로그분석을 이용하여 웹 객체의 참조특성을 분석하고, 이 참조특성의 분석 결과를 기반으로 분할된 웹 캐시 대체 기법을 제안하고 실험하였다. 실험 결과에서는, 제안 기법이 기존의 기법에 대해 객체 적중률과 응답속도의 성능이 개선되었음을 확인할 수 있다. Generally we use web cache in order to increase performance of web base system, and a replacement technique has a great influence on performance of web cache. A web cache replacement technique is different from a replacement technique of memory scope, and a unit substituted for is web object Also, as for the web object, a variation of user reference characteristics is very great. Therefore, a web cache replacement technique can reflect enough characteristics of this web object. But the existing web caching techniques were not able to reflect enough these object reference characteristics. A principal viewpoint of this study is reference characteristic analysis, an elevation of an object hit rate, an improvement of response time. First of all we analyzed a reference characteristics of an web object by log analysis. And we divide web cache storage scope using the result of reference characteristics analysis. In the experiment result, we can confirm that performance of an object-hit ratio and a response speed was improved than a conventional technique about a proposal technique.

A survey of Web cache replacement strategies

Web caching is an important technique to scale the Internet. One important performance factor of Web caches is the replacement strategy. Due to specific characteristics of the World Wide Web, there exist a huge number of proposals for cache replacement. This article proposes a classification for these proposals that subsumes prior classifications. Using this classification, different proposals and their advantages and disadvantages are described. Furthermore, the article discusses the importance of cache replacement strategies in modern proxy caches and outlines potential future research topics.

Review of Web caching and replication by Michael Rabinovich and Oliver Spatscheck. Addison Wesley 2002.

Review of Web caching and replication by Michael Rabinovich and Oliver Spatscheck. Addison Wesley 2002.

Research feature - Scaling web services with capacity provision networks

With the increasing proliferation of c-commerce and e-business activities, many service providers are turning to Web caching solutions to move important content and processes closer to end users. Uncertainties in user demand and rapid market changes pose significant impediments to effective cache planning and deployment solutions, however. The authors have developed capacity provision networks to support a specific type of Web caching in the vertical segment of ISPs, NSPs, and similar entities. In this scenario, an entity can be a provider at one time and a user at another, depending on cache capacity requirements.

Preserving peer replicas by rate-limited sampled voting

The LOCKSS project has developed and deployed in a world-wide test a peer-to-peer system for preserving access to journals and other archival information published on the Web. It consists of a large number of independent, low-cost, persistent web caches that cooperate to detect and repair damage to their content by voting in "opinion polls." Based on this experience, we present a design for and simulations of a novel protocol for voting in systems of this kind. It incorporates rate limitation and intrusion detection to ensure that even some very powerful adversaries attacking over many years have only a small probability of causing irrecoverable damage before being detected.

World Wide Wait: A Study of Internet Scalability and Cache-Based Approaches to Alleviate It

The Internet is growing rapidly in terms of both use and infrastructure. Unfortunately, demand is outpacing the capacity of the infrastructure, as evidenced by unacceptably long response times. To support current load and further growth, we must address this problem. Several caching strategies have been proposed in the literature; many have been implemented to improve the quality of service on the Web. In this paper, we identify the main causes of delay on the Web, and provide a review of the various caching strategies employed to mitigate these delays. We also survey the application of Operations Research/Management Science (OR/MS) techniques to caching on the Web. Finally, we identify several open OR/MS research problems related to Web caching.

Estimating frequency of change

Many online data sources are updated autonomously and independently. In this article, we make the case for estimating the change frequency of data to improve Web crawlers, Web caches and to help data mining. We first identify various scenarios, where different applications have different requirements on the accuracy of the estimated frequency. Then we develop several "frequency estimators" for the identified scenarios, showing analytically and experimentally how precise they are. In many cases, our proposed estimators predict change frequencies much more accurately and improve the effectiveness of applications. For example, a Web crawler could achieve 35% improvement in "freshness" simply by adopting our proposed estimator.

On scalable and locality-aware web document sharing

We propose a scalable Web document sharing infrastructure model called Browsers-Aware Proxy Server. In this design, a proxy server connecting to a group of networked clients maintains an index file of data objects of all clients’ browser caches. If a user request misses in its local browser cache and the proxy cache, the browsers-aware proxy server will search the index file attempting to find it in another client's browser cache before sending the request to an upper level proxy or the Web server. If such a request does hit in a remote client, this client will directly forward the data object to the requesting client; or the proxy server fetches the data object from this client and then forwards it to the requesting client. The contributions of this caching model are twofold. First, we show that the amount of sharable data in browser caches is significant and can be utilized for document sharing among clients to improve Web caching performance and scalability. Second, the browsers-aware model can effectively and further improve Web prefetching performance. The browsers-aware model and its supported prefetching technique build a strong locality-aware Internet environment to make Web accesses fast with low communication costs. Conducting trace-driven simulations, we show the effectiveness of the browsers-aware model, and its unique advantages to facilitate prefetching.

Delay sensitive least frequently used algorithm for replacement in web caches

Caching at proxy servers plays an important role in reducing the response time, network delays, and load on the Web servers. The performance of caching depends critically on the design of the cache replacement algorithm. Most of the cache replacement algorithms consider only Hit-Ratio or Byte-Hit-Ratio, and ignore the fetch time of the documents to the cache. In this paper, a new delay conscious cache replacement algorithm has been proposed. The proposed algorithm considers the retrieval time of the document from servers in addition to the frequency of references to the document, the document size, and an ageing factor and maximizes a performance metric called Communication Delay Ratio (CDR). 1 1 CDR is defined as the ratio of reduction in delay due to caching to the delay without caching. The new algorithm has been tested and compared to the existing policies such as, LRU, LFU, LNC-R-W3, and Greedy-Dual-Size Frequency.

Web cache optimization with nonlinear model using object features

In this paper, Web cache optimization by utilizing syntactic features extracted from cache objects is studied. A nonlinear model is used to predict the value of each cache object by using features from the HTTP responses of the server, the access log of the cache, and from the HTML structure of the object. In a case study, linear and nonlinear models are used to classify about 50,000 HTML documents according to their popularity. The nonlinear model yields classification percentages of 64 and 74 for the documents to be stored or to be removed from the cache, respectively. A synthetic workload is then used to study the performance gain from the classifier in a conventional Least Recently Used cache model. The results suggest that the proposed approach can improve the performance of the cache substantially.

Web-log mining for predictive web caching

Caching is a well-known strategy for improving the performance of Web-based systems. The heart of a caching system is its page replacement policy, which selects the pages to be replaced in a cache when a request arrives. In this paper, we present a Web-log mining method for caching Web objects and use this algorithm to enhance the performance of Web caching systems. In our approach, we develop an n-gram-based prediction algorithm that can predict future Web requests. The prediction model is then used to extend the well-known GDSF caching policy. We empirically show that the system performance is improved using the predictive-caching approach.

An overview of DNS-based server selections in content distribution networks

With the explosive growth of the Internet, many new online services and applications are emerging. Some popular applications impose new challenges to the traditional Internet architecture and protocols. To alleviate the scalability burden in delivering popular Internet services to a large number of users, Web caching and content distribution technologies have been proposed, developed and deployed. Both approaches are designed to bring Web content closer to users and to improve their perceived quality of online experience. This paper surveys content distribution networks (CDNs), and in particular, their domain name system (DNS)-based server selection schemes. To bridge the gap between underlying principles and current practices, we choose a commercial content delivery provider, Akamai, as our focal case study. We first unveil Akamai’s content delivery network, as well as its site and object delivery technologies. We then examine the DNS-based server selection schemes and their variants in detail. Moreover, we offer some performance insights and discussions on their built-in strengths and weaknesses that are also applicable to other CDN providers.