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Title: | 考慮地域鄰近性且群組化的點對點範圍查詢系統 A Proximity-Aware and Group-Based Peer-to-Peer System for Range Queries |
Authors: | Wing-Tat Wong 黃榮達 |
Advisor: | 莊裕澤(Yuh-Jzer Joung) |
Keyword: | 點對點網路,範圍查詢,鄰近性,群組化,負載平衡, Peer-to-Peer,Range Queries,Proximity,Grouping,Load Balance, |
Publication Year : | 2007 |
Degree: | 碩士 |
Abstract: | 在過去的幾年裡,點對點系統為大規模的分散式資訊系統形成一個強大的平台。在這種平台裡,搜尋系統裡的資源是十分重要的一種功能,並且已經有不少的研究提出方法來改善系統中搜尋的效能;然而,點對點平台並不是對於任何類型的查詢都能有效的支援,例如對於範圍查詢的支援仍然有限。要在點對點平台上有效的支援範圍查詢,首先我們必須解決影響效能的相關問題﹕系統內部的高通訊成本、點與點之間的負載不平衡以及維持系統裡物件的有效性。在過去的研究中雖然有針對單一問題提出不錯的解決方法;不過,因為這些問題之間存在著衝突性,所以尚未有一個系統可以同時有效地解決這些問題。在這篇論文裡,我們提出了一個可靠的點對點系統,它可以維持物件的有效性及有效地支援範圍查詢。我們的系統會考慮地域鄰近性及利用合作式的cache機制來處利高通訊成本的問題。同時,我們也會利用群組化的概念來解決地域鄰近性與負載平衡之間的衝突。在一個群組化的系統裡,每一個節點會被分派到不同的群組以提昇地域鄰近性的彈性,這樣可以增加實行負載平衡的可行性,因為物件會被均等地分配到不同的群組當中。
我們的實驗結果證明了我們的平台可以在一個高度不穏定的環境下維持正常的操作,而考慮地域鄰近性的機制也可以有系統化地降低通訊的成本;在另一方面,合作式的cache機制會經由降低系統裡搜尋的範圍以及貯藏物件的重複性來增加系統搜尋的效能。最後,我們所提出的負載平衡機制亦能夠以低成本在一個具有物件順序的限制情況下快速地平衡點與點之負載。 Peer-to-peer (P2P) systems have emerged promptly as a powerful platform for large-scale distributed information systems in recent years; important functionalities, such as searching, have been added to improve the system's lookup capability. In particular, range query is exceptionally demanded when a user does not know exactly what he/she is looking for, however, the efficient support of range queries in a P2P system is still a challenging problem. To resolve this problem, some other related issues must first be addressed, such as high communication overheads, load imbalance among peers and preservation of object availability. Several techniques have been proposed in each aspect, but it is difficult to incorporate all of them in a single range queries system due to the conflict among these techniques. In this thesis, we propose a fault-tolerable P2P system which guarantees object availability and supports range queries effectively. The system exploits proximity and cooperative caching to tackle the high communication overhead. By introducing the concept of grouping, the conflict between proximity and load balance can be resolved. Within a grouping environment, peers are divided into several groups to provide the flexibility of proximity and feasibility of load balance in a range queries system. Therefore, objects are evenly distributed among groups. Our results show that our platform is fault-tolerable in a highly dynamic environment. The impact of proximity is effective in reducing the communication overhead. Moreover, the cooperative cache scheme can improve search performance, decrease the query scope significantly and avoid redundancy. The load balance mechanism can quickly balance the load among peers under object ordering constraint environment with a low cost. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/28688 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 資訊管理學系 |
Files in This Item:
File | Size | Format | |
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ntu-96-1.pdf Restricted Access | 2.75 MB | Adobe PDF |
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