在許多領域的研究中，從 P2P 系統裡找資料已經變得愈來愈重要。在所有查詢相關的研究中， 能找出排名前K個物件的 Top-K 查詢在很多 P2P 網路應用是很急需的。然而，把在P2P 系統中導入 Top-K 技術會面臨一些困難： P2P 系統中有大量的電腦節點 (Peer)、每個 Peer 的行為不受拘束、 Peer 所含有的資料變動性很大。在這種情況之下，如果直接導入專為靜態環境和固定資料資料而設計的傳統 Top-K 技術將會產生過多、而且不必要的通訊量，進而影響整個 P2P 系統的效率。針對這些問題，我們在這篇論文中提出了一個有效的方法可以在 P2P 系統中執行連續性的 Top-K 查詢。這個架在 Superpeer 架構上的方法包含了1)可以掌握所有 Peer 最新動態的更新機制、和2)處理 Superpeer 之間資料傳遞的分散機制。根據我們的實驗結果，這個方法可以提供不錯的結果，同時也能減少了相當可觀的通訊量。

The research regarding locating specified resources in peer-to-peer (P2P) systems has become more and more important in many research communities nowadays. Among all query-related studies, the technique of top-k queries, which can locate the k objects with the highest overall rankings, is urgently demanded in many network applications. However, employing traditional top-k techniques in P2P systems faces some problems. P2P systems are characterized by large-scale, free peer behaviors, and dynamic data. Under the circumstances, the techniques designed for static environments and data would probably generate many unnecessary traffic messages and consume huge computation cost. To ease these problems, we propose an effective solution for continuous top-k query in P2P systems in this paper. The proposed technique, based on superpeer topology, consists of a reliable update mechanism between peers and a distributing mechanism between superpeers. As the experimental results show, the proposed technique can provide comparable results while reducing considerable communication cost.

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