行動代理者(Mobile agent)是可在一異質網路系統(Heterogeneous network system)內從一主機(Host)遷移(Migrate)至另一主機併和其他代理者及分散資源系統(Distributed resources)溝通及交互作用(Interact)之軟體程式。它們特別適合用來發展分散式及網路上的應用系統。而行動計算(Mobile computing)在近年來漸漸得到更多的重視，因為更多的專業人士發覺了使用行動平台(Mobile platform)，如行動電腦(Mobile computer)及個人資料擷取器(PDA)以無線網路連接上有線網路後，可隨時隨地、了無限制擷取廣大而分散在各處的資訊的好處。
雖然有相當多的學術及商業應用上的研究，但是行動代理者系統容錯機制的研究仍然尚未明朗，使得行動代理者系統的可靠性令人質疑。使用者無法確定派遣出去代理者能否順利完成任務，而這也是行動代理者技術一直尚未被導入至實際應用領域的一個重要原因。本研究的主要目的是設計一套能夠與現存的行動代理者系統整合，並賦予行動代理者系統容錯能力的基礎架構。本研究所提出的設計，以階層式架構為基礎，並融合集中式容錯機制架構與分散式容錯機制架構的優點，且具有良好的擴充性及可靠性。

Mobile agents are software programs that can migrate from host to host and interact with other agents and distributed resources in a heterogeneous network. They are therefore particularly effective for developing distributed applications. Mobile computing is also gaining more and more popularity in the recent years as professionals discover the benefits of being able to connect to the vast of distributed information resources at all times without any spatial constraints.

Although mobile agents have attracted considerable interest in academia and business application, fault tolerance for mobile agent systems is an unsolved topic. Therefore the reliability of mobile agent systems is doubtful. The agent owner cannot be sure about whether the agent can complete its task successfully or may fail. Thus, mobile agent technology is not applied to real applications so far. The purpose of our research is to propose an essential framework that can integrate with mobile agent systems. The proposed architecture will combine advantages of centralized fault tolerant mechanism and distributed fault tolerant mechanism, and achieve scalability and reliability.

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