• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.8C
• /
• pp.670-679
• /
• 2012

The recent dissemination of cloud computing makes the amount of data storage to be increased and the cost of storing the data grow rapidly. Accordingly, data and service requests from users also increases the load on the cloud storage. There have been many works that tries to provide low-cost and high-performance schemes on distributed file systems. However, most of them have some weaknesses on performing parallel and random data accesses as well as data accesses of frequent small workloads. Recently, improving the performance of distributed file system based on caching technology is getting much attention. In this paper, we propose a CHPC(Cloud storage High-Performance Caching) framework, providing parallel caching, distributed caching, and proxy caching in distributed file systems. This study compares the proposed framework with existing cloud systems in regard to the reduction of the server's disk I/O, prevention of the server-side bottleneck, deduplication of the page caches in each client, and improvement of overall IOPS. As a results, we show some optimization possibilities on the cloud storage systems based on some evaluations and comparisons with other conventional methods.

• Journal of information and communication convergence engineering
• /
• v.8 no.3
• /
• pp.245-250
• /
• 2010

To support various bandwidth requirements for many kinds of devices such as PC, notebook, PDA, cellular phone, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. Due to huge size of streaming media, we proposed the 3 kinds of segmentation - PT-2, uniform, bitrate-based segmentation. And to reduce the CPU cost of transcoding video, we proposed the DQS service policy. In this paper, we simulate the combined our previous two researches that are bitrate-based segmentation and DQS(Degraded Quality Service) policy. Experimental results show that the combined policy outperforms companion schemes in terms of the byte-hit ratios and delay saving ratios.

• Journal of Information Technology and Architecture
• /
• v.10 no.2
• /
• pp.159-167
• /
• 2013

Web Services offer many benefits over other types of middleware in distributed computing. However, usage of Web Services results in large network bandwidth since Web Services use XML-based protocol which is heavier than binary protocols. Even though there have been many researches to minimize the network traffic and bandwidth usages of Web Services messages, none of them are solving problem clearly yet. In this paper, we propose a transparent proxy with cache to avoid transfer of repeated SOAP data, sent by Web Service to an application. To maintain the cache consistency, we introduce publish/subscribe paradigm using WS-Eventing between the proxy and Web Service. The implemented system based on our proposed architecture will not compromise the standards of Web Service. The evaluation of our system shows that caching SOAP messages not only reduces the network traffic but also decreases the request delays.

• The KIPS Transactions:PartC
• /
• v.10C no.1
• /
• pp.87-94
• /
• 2003

As the number of the Internet users increases explosively, a solution for this problem is web caching. So, many techniques on improving cache server performance have been suggested. In this paper, we analyze the cause of the bottleneck in cache servers, and propose an arbitral thread and delayed caching mechanism as a solution. We use an arbitral thread in order to provide a quick service to user requests through eliminating the ready multi-thread search problem in case of disk writing operation. We also use delayed caching in order to provide stable system operation through avoiding overloaded disk operation and queue threshold. Proposed cache server is implemented through modification on SQUlD cache server, and we compare its performance with the original SQUID cache server.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06a
• /
• pp.421-423
• /
• 2006

본 논문에서는 무선 인터넷 프록시 서버 클러스터를 사용하여 무선 인터넷의 문제와 요구들을 캐싱(Caching), 압축(Distillation) 및 클러스터(Clustering)를 통하여 해결하려고 한다. 무선 인터넷 프록시 서버 클러스터에서 고려되어야 하는 것은 시스템적인 확장성, 단순한 구조, 캐시간 협동성(Cooperative Caching), Hot Spot에 대한 처리 등이다. 본 연구자들은 기존 연구에서 시스템적인 확장성과 단순한 구조물 가지는 CD-A라는 구조를 제안하였으나 캐시간 협동성이 없다는 단점을 가진다. 이의 개선된 구조로 해쉬를 이용하여 사용자의 요청을 처리하는(캐시간 협동성을 가지는) 구조를 생각해 볼 수 있으나 이 역시 Hot Spot을 처리할 수 없다는 단정을 가진다. 이에 본 논문에서는 시스템적인 확장성, 단순한 구조, 캐시간 협동성, Hot Spot을 처리할 수 있는 공유 스토리지 기반의 무선 인터넷 프록시 서버 클러스터를 제안한다. 제안된 방법은 하나의 캐시 디렉토리를 공유하는 방법으로 기존구조의 장점과 캐시간 협동성 및 Hot Spot을 처리할 수 있다는 장점을 가진다. 16대의 컴퓨터를 사용하여 실험을 수행하였고 실험 결과 Hot Spot 상황에서 제안된 방법이 높은 성능 향상을 가짐을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.70.3-70
• /
• 2001

In this paper, we suggest a kernel level multi thread web accelerator (called the SCALA-AX), which significantly improves the performance of the web soerver. In comparison with a conventional proxy web cache that is generally called a caching server and a simple content-copy based system, the primary functions and goals of SCALA-AX are designed to maximize the content services of a front end web server with high performance. Specifically, the SCALA-AX runs on the kernel level of a web sorrel, based on the newest caching techniques. Moreover, the SCALA-AX supports the http 1.1 protocol and allows the dynamic pages as well as static pages to be processed.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.05a
• /
• pp.125-128
• /
• 2007

최근 사용자의 멀티미디어 서비스 요구가 보편화되면서 네트워크에 걸리는 부하가 늘어나게 되었고, 사용자들이 미디어를 다운로드한 후 플레이하는 방법보다 스트리밍 서비스를 선호함에 따라 실시간성이 더욱 중요시되고 있다. 웹 서비스에 전통적으로 사용되는 프록시 서버는 네트워크의 가장자리에 위치하여 클라이언트와 서버 사이의 거리 때문에 발생하는 문제를 주로 해결한다. 하지만 고 대역폭과 긴 서비스 시간이라는 특징을 가지는 멀티미디어 스트리밍 서비스에서는 전통적인 웹 프록시의 장점을 제대로 활용하기 어렵다. 본 논문에서는 미디어 스트리밍 서비스에서 네트워크 트래픽을 감소시키고 서비스 지연시간을 줄이기 위한 새로운 캐슁 전략을 제안한다. 제안된 전략에서 프록시 서버는 미디어 데이터의 일부와 미디어의 프리픽스를 캐슁하여 클라이언트가 요청한 미디어를 바로 인접한 프록시에서 찾도록 하여, 고 대역폭을 사용하는 스트리밍 시스템에서 네트워크 부하와 초기 지연을 줄인다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.6
• /
• pp.346-353
• /
• 2002

The explosive increase of World Wide Web usage has incurred significant amount of network traffic and server load. To overcome these problems, web proxy caching replicates frequently requested documents in the web proxy closer to the users. Cache utilization depends on the replacement policy which tries to store frequently requested documents in near future. Temporal locality and Zipf frequency distribution, which are commonly observed in web proxy workloads, are considered as the important properties to predict the popularity of documents. In this paper, we propose a novel cache replacement policy, called Adaptive LFU (ALFU), which incorporates 1) Zipf frequency distribution by utilizing LFU and 2) temporal locality adaptively by measuring the amount of the popularity reduction of documents as time passed efficiently. We evaluate the performance of ALFU by comparing it to other policies via trace-driven simulation. Experimental results show that ALFU outperforms other policies.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06a
• /
• pp.339-340
• /
• 2008

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.10c
• /
• pp.355-357
• /
• 2003

본 논문은 기존에 제시되었던 협동적 캐슁 프록시 서버의 구조에 프록시 서버에 독립적인 prefix 배치와 프록시 서버간의 suffix 공유라는 동작을 추가하여, 무선 상에서의 효율적인 멀티미디어 콘텐츠 스트리밍이 가능하도록 하였다. 제안한 구조에 적합한 동작방법과 알고리즘 및 이에 따른 prefix의 특성을 제시하며, 콘텐츠 초기 지연 시간의 감소와 서버저장 능력 향상에 대한 성능 개선 효과를 기술한다.