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題 名 | 行動計算系統中之毀壞復原演算法=An Efficient Rollback Recovery Algorithm for Distributed Mobile Computing Systems |
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作 者 | 陳裕賢; 張育霖; | 書刊名 | 統計與資訊評論 |
卷 期 | 5 1999.09[民88.09] |
頁 次 | 頁31-46 |
分類號 | 448.82 |
關鍵詞 | 行動計算系統; 檢查點; 毀壞復原; 行動主機; Mobile computing systems; Checkpoints; Crash recovery; Mobile hosts; |
語 文 | 中文(Chinese) |
中文摘要 | 無線通訊技術快速的發展使得行動計算系統(mobile computing system)得以實現,而應用程式欲發揮新運算環境的優點勢必充份運用其特性。其中毀壞復原在行動計算系統中更是一值得研究探討的問題。在論文中對於行動計算系統環境我們提出一個有效率的毀壞復原演算法。在系統正常運作中或執行毀壞復原演算法時,兩者皆不需維持或尋找”全域之一致性檢查點”(Global Consistent C heckpoint 簡稱GCC)且當系統執行毀壞復原程序時,僅要求與損壞的行動電腦有訊息相依的行動電腦回復至最近之訊息事件而非GCC。系統正常運作時在有線網路中,行動電腦基地站〈mobile support station簡稱MSS〉間之訊息複雜為O(n□_□),而在無線網路中為O(1),也就是在行動電腦回應MMS的確認訊息中附帶一”接收事件序號(event number)”。在演算法中,MSS利用矩陣n□_□*n□_□〈其中n□_□為行動計算系統中行動電腦之總數,n□_□為一無線通訊網路所含蓋範圍中行動電腦之總數〉,記錄整個行動計算系統環境中行動電腦間訊息相依的資訊。同時,我們亦討論了兩個相關的議題「重傳遺失的訊息」及「清除過時的訊息記錄」。在重傳遺失訊息的問題中,我們在每個MSS維護兩個大小為n□_□*n□_□的矩陣SENT及RECEIVED,用以記錄系統中MH間收送訊息的個數。在執行復原程序時,僅需比較MH間訊息送收之個數即可得知是否有遺失之訊息,進而決定需重傳之訊息為何。在處理過時的訊息記錄中,MSS利用相依矩陣即可快速的判斷出過時的訊息記錄,而且此作業並不影響系統中其他MH的運作。 |
英文摘要 | One major breakthrough on the communication society recently is the extension of networking from wired to wireless networks. This ahs made possible creating a mobile distributed computing environment and has brought us several new challenges in distributed protocol design. Obviously, wireless networks do have some fundamental differences from wired networks that need to be paid special attention of, such as lower communication bandwidth compared to wired networks, limited electrical power due to battery capacity, and mobility of processes. These new make traditional recovery algorithm unsuitable. In order to cope with these problems, the tasks of logging and recovery procedure are performed by the MSSs. In this paper, we propose an efficient algorithm with O(n□) message complexity where n, is the total number of mobile hosts (MHs) related to the failed MH. In addition, these MHs only need to rollback once and can immediately resume its operation without waiting for any coordination message from other MHs. During normal operation, the application message needs O(1) additional information when it transmitted between MHs and mobile support stations (MSSs). Each MSS must keep an n□*n□ dependency matrix, where n□ is the total number of MHs in the system and n□ is the total number of MHs in its cell. Finally, two related issues of resending lost messages and garbage collection are also considered. |
本系統中英文摘要資訊取自各篇刊載內容。