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研究生:盧正隆
研究生(外文):Jeng-Lung Lu
論文名稱:適應性租約:一個在WWW快取伺服器上的同步機制
論文名稱(外文):Adaptive Leases:A Strong Consistency Mechanism for WWW Proxy
指導教授:簡榮宏簡榮宏引用關係
指導教授(外文):Rong-Hong Jan
學位類別:碩士
校院名稱:國立交通大學
系所名稱:資訊科學系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:中文
論文頁數:40
中文關鍵詞:快取快取伺服器同步租約適應性租約全球資訊網
外文關鍵詞:ProxyCacheConsistencyWWWLeaseAdaptive Lease
相關次數:
  • 被引用被引用:1
  • 點閱點閱:491
  • 評分評分:
  • 下載下載:20
  • 收藏至我的研究室書目清單書目收藏:0
WWW的興起為網路流量帶來驚人的成長,造成網路的壅塞與伺服器負荷的增加。快取(cache)在網際網路上被廣為使用,它可以減低網路流量,減少存取延遲與減輕伺服器的負荷,然而要保證快取內資料的正確性,快取同步技術隨之興起。目前常見的快取同步之研究有:適應性存活時間(Adaptive TTL)、每讀詢問(Poll-Each-Read)、伺服器通知(Callback)與租約(Lease)等方法。如何決定物件在快取伺服器中的存活時間是一個重要的問題,我們提出了一種適應性租約(Adaptive Lease)的方式來決定物件的存活時間,它不但可以達到強同步的效果,還可以減少傳統方法在記憶體以及頻寬使用上的浪費。此外,我們也利用實驗來瞭解快取伺服器的容量大小和系統效能之間的關係,而結果顯示兩者之間並無明顯的關係。最後我們用數學的模式來分析在相同的租約存活時間下所需要傳送的訊息(messages)數量,並且用模擬方式來驗證理論值的正確性。
Caching objects can reduce network traffic, client response time and server memory usage. However, to make sure that cached copy is up-to-date or not, cache consistency mechanism should be maintained. There are several well-known approaches to maintain cache consistency: Adaptive TTL, Poll-Each-Read, Callback and Lease, but how to choose the object’s lifetime is a trade-off problem. In this thesis, we propose an Adaptive Lease approach to determine caching object’s lifetime. This approach can not only achieve strong consistency, but also reduce server memory usage and control message transmission. Furthermore, we find out the relationship between cache size and system performance. The simulation result shows their relationship is very slightly. Finally, we estimate the control messages transmitted for Constant Lease approach by mathematical analysis and use trace-based simulation to verify our estimation.
1. Introduction
2. Related Work
2.1 Weak Cache Consistency Approach
2.1.1 Adaptive TTL Approach
2.1.2 Two-State TTL Approach
2.2 Strong Cache Consistency Approach
2.2.1 Poll-Each-Read Approach
2.2.2 Callback(Invalidation) Approach
2.2.3 Lease Approach
3. Adaptive Lease Approach
3.1 Zipf-Like Distribution
3.2 Adaptive Lease Approach
3.3 Simulations
3.3.1 Summary of Log Files
3.3.2 Simulation Results
4. Estimation of Control Messages Transmission
4.1 Definition of Access Cycle
4.2 Expected Control Messages
4.3 Simulation
5. Conclusion
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"Summary Cache: A Scalable Wide-Area Web Cache Sharing Protocol", IEEE/ACM Transactions on Networking, Vol. 8, June 2000, pp.
281 -293.
[2] A. Mahanti, C. Williamson, and D. Eager, University of Saskatchewan, "Traffic Analysis of a Web Proxy Caching Hierarchy", IEEE Network, May/June 2000, pp. 16 -23.
[3] W. Meira, E. Fonseca, C. Murta, and V. Almeida,
"Analyzing performance of cache server hierarchies", IEEE
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[4] P. Cao, and C. Liu, "Maintaining Strong Cache Consistency In WWW", IEEE Transactions on Computers, Vol. 47 Issue: 4, April
1998, pp. 445 -457.
[5] J. Yin, L. Alvisi, M. Dahlin, and C. Lin,
"Volume Leases for consistency in large-scale systems", IEEE
Transactions on Knowledge and Data Engineering, vol. 11,
July-Aug. 1999, pp. 563 -576.
[6] V. Cate, "Alex - A Global Filesystem", Proc. USENIX File Sys. Wksp., May 1992, pp. 1 -12.
[7] Squid proxy cache server and its user guide.
Available on-line at http://www.squid-cache.org/.
[8] J. Gwertzman, and M. Seltzer, "World-Wide Web Cache Consistency", in Proc. 1996 Usenix Technical Conference, (San Diego, CA), January 1996.
[9] C. Gary, and D. Cheriton, "Lease: An Efficient
Fault-Tolerant Mechanism for Distributed File Cache Consistency", Proc. 12th ACM Symb. Operating Systems Principles, pp. 522 -525, 1992
[10] J. Yin, L. Alvisi, and M. Dahlin, "Using Leases to Support Server-Driven Consistency in Large-Scale-Systems", Proc. 18th Int''l Conf. Distributed Computing Systems}, May 1998.
[11] V. Duvvuri, P. Shenoy, and R. Tewari, "Adaptive Leases: a strong consistency mechanism for the World Wide Web", IEEE Proc. 19th Annual Joint Conference of the IEEE Computer and Communications Societies, vol. 2, 2000, pp. 834 -843.
[12] X. Chen, and P. Mohapatra, "Lifetime Behavior and Its
Impact on Web Caching", Internet Applications, 1999. IEEE Workshop on , 1999 pp. 54-61.
[13] V. Jacobson. "Congestion Avoidance and Control", In Proc. SIGCOMM ''88 Workshop, pp. 314-329. ACM SIGCOMM, ACM Press, August 1988. Stanford, CA.
[14] R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, and T. Berners-Lee, Hypertext Transfer Protocol -- HTTP/1.1, RFC 2616, June 1999.
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