隨著網際網路 (Internet)﹑分散式系統及以及物件導向 (object-oriented) 技術的發展，以分散式物件為基礎的分散式處理也越形重要。而OMG (Object Management Group) 所制定的CORBA (Common Object Request Broker Architecture)﹐因為其具備開放﹑標準化的特質﹐所以備受程式設計人員的青睞。
目前在CORBA 3.0上已經制定了15個共通物件服務規範 (Common Object Service Specification﹐COSS) 來協助分散式應用程式的開發﹐但是至今尚無容錯服務相關標準的制定。然而﹐分散式應用程式仍然必須面對與解決不可預期的程序故障﹑主機故障或是通訊網路中斷等等故障的產生。
在這篇論文中﹐我們在CORBA的環境上提出了一個以重複物件 (replicated object) 為基礎的容錯物件服務 (Fault-Tolerant Object Service﹐簡稱FTOS)。在FTOS中﹐包含了動態投票 (dynamic voting) 機制以及物件複製機制。物件式動態投票機制使用多數決 (majority) 投票策略以確保在故障情況下﹐物件狀態仍維持一致性。而物件複製機制則可以協助系統管理人員輕易地複製及啟動物件。在實作上﹐我們依照COSS的規格定義了一個程式庫﹐程式設計人員可以利用所提供的程式庫﹐輕易地製作出具有容錯能力的分散式應用程式。

With the development of Internet, distributed systems and object-oriented technology, object-based distributed processing is more and more important. CORBA (Common Object Request Broker Architecture), established by OMG (Object Management Group) has been highly valued by programmers because of its property of openness and standardization.
CORBA 3.0 provides 15 COSS (Common Object Service Specification) for distributed application development, but none of them provides fault-tolerance related services exists now. However, distributed applications still have to face and deal with many fault-tolerant issues such as unpredictable process failures, host failures and networks partition.
In this paper, we propose a replicated object based Fault-Tolerant Object Service (FTOS) for CORBA environment. Two fault-tolerant mechanisms are provided in FTOS including dynamic voting mechanism and object replication mechanism. The dynamic voting mechanism uses majority voting strategy to ensure object state consistency in failure situations. The object replication mechanism can help system administrators to replicate and start-up objects easily. Our implementation provides a library according to the style of COSS. With this library, programmers can develop distributed applications with fault-tolerance capability very easily.

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