分散式物件技術在日益成熟之後，逐漸成為運算模式的主流。而W3C（World Wide Web Consortium）所制定的SOAP（Simple Object Access Protocol）是架構在XML（Extensible Markup Language）之上的分散式溝通協定，具有簡單、開放、標準化等特質。面對廣域網路的異質環境，若要實現分散式物件技術，SOAP會是一個真正跨平台、跨語言的解決方案。在這個新協定中，容錯技術的實作尚無標準，然而處於分散式環境的物件，可能因為主機故障或網路中斷等因素，無法正確運作。為了使系統能有更高的可用度（Availability），必須加入容錯技巧。
SOAP的規格定義中，並無物件註冊與找尋之相關規定，本論文乃提出具有容錯能力之Quorum-based Domain Name Service以實現此機制，並利用SOAP Message達成物件複製（Object Replication）。本系統內之物件皆以SOAP為訊息溝通協定，且已實現主體-備份（Primary-Backup）、動態投票（Dynamic Voting）、Quorum等不同的容錯策略，因此可稱為SOAP-based容錯物件服務平台。所有容錯策略均封裝在基礎類別（Base Class）中，應用物件開發人員可以利用繼承機制使其成果迅速獲得容錯能力。在電子商務領域中，容錯服務有其必要性，因此本平台可以應用於這類資訊系統的設計。最後，本論文實作了股市資訊、郵局帳號管理、聊天室等示範系統，藉以展現容錯平台之能力以及應用物件之實作方法。

With the rapid-growing popularity of distributed computing, a simple, open and standard protocol, SOAP (Simple object Access Protocol), over the interoperable environment is indispensable. Based on the technology of XML (Extensible markup language), SOAP will become a new cross-platform and cross-language solution of distributed computing. But, as an innovation standard for distributed computing, the lack of fault-tolerant ability for SOAP will limit its application. In order to increase the availability of business objects, an accretion of fault-tolerant capability on SOAP is essential.
Because of the shortage of Naming Service definition in SOAP specification, we propose a fault-tolerant Quorum-based Domain Name Service to meet this requirement. We use SOAP Message to realize object replication and inter-object communication, and then construct a SOAP-based Fault-tolerant Object Service Platform. It comprises base classes of Primary-Backup, Dynamic Voting and Quorum-based object. Taking advantage of object hierarchy, business object developers can build fault-tolerant object easily by inheritance mechanism. In the e-commerce transaction, fault-tolerant service is imperative; therefore our platform is necessary for enterprise-related information systems. We also implement some examples like Stock Quote, Post Office and Chat Room to demonstrate fault-tolerant ability of our platform and the practices of fault-tolerant business object.

[1] John J. Barton, Satish Thatte and Henrik Frystyk Nielsen, “SOAP Messages with Attachments,” HTTP DOC, December 2000,
http://www.w3.org/TR/SOAP-attachments
[2] Harmeet Bedi, Jonathan Chawke, Franciso Curbera, Glen Daniels, Doug Davis, Matthew J. Duftler, Kevin Mitchell, William Nagy, Scott Nichol, Sam Ruby, James Snell, Sanjiva Weerawarana, “Apache SOAP,”
http://xml.apache.org/soap
[3] Grady Booth, Ivar Jacobson and James Rumbaugh, “UML Distilled Second Edition,” Addison Wesley Longman, Inc. 2000.
[4] Don Box, David Ehnebuske, Gopal Kakivaya, Andrew Layman, Noah Mendelsohn, Henrik Frystyk Nielsen, Satish Thatte, Dave Winer, “Simple Object Access Protocol (SOAP) 1.1,” HTTP DOC, May 2000,
http://www.w3.org/TR/SOAP/
[5] T. D. Chandra and S. Toueg, “Unreliable failure detectors for reliable distributed systems,” J. ACM, vol. 43, pp.225-267, Mar. 1996.
[6] George Coulouris, Jean Dollimore and Tim Kindberg, “Distributed Systems Concepts and Design,” Addison-wesley 2001.
[7] Xavier Defago, Andre Schiper and Nicole Sergent, “Semi-Passive Replication,” Symposium on Reliable Distributed Systems. pp.43-50, 1998.
[8] Wolfgang Emmerich, Cecilia Mascolo and Anthony Finkelstein, “Implementing incremental code migration with XML,” Proceedings of the 22nd international conference on Software engineering. 2000, Limerick, Ireland, pp.397-406.
[9] R. Guerraoui and A. Schiper, “Fault-Tolerance by Replication in Distributed Systems,” Reliable Software Technologies, Springer-Verlag, pp.38-57, 1996.
[10] S. Jajodia and D. Mutchler, “Dynamic Voting,” ACM SIGMOD International Conference on Management of Data, pp.227-238, San Francisco, 1987.
[11] Pankaj Jalote, “Fault Tolerance in Distributed Systems,” Prentice-Hall International, Inc, 1994.
[12] “Java API for XML Messaging (JAXM),”
http://java.sun.com/xml/jaxm/
[13] Markus Lindermeier, “Load Management for Distributed Object-Oriented Environments,” In 2nd International Symposium on Distributed Objects and Applications (DOA'00), pages 59-68, Antwerp, Belgium. IEEE Computer Society, 2000.
[14] Silva L.M.; Batista V. and Silva J.G., “Dependable Systems and Networks,” Proceedings International Conference, New York, NY, USA 2000, pp-135-143.
[15] Brendan Macmillan, “Java Serialization to XML,”
http://www.csse.monash.edu.au/~bren/JSX/
[16] Brett McLaughlin, “JAVA and XML,” O’REILLY, June 2000.
[17] Seoyoung Park and Chisu Wu, “Intelligent search agent for software components,” Software Engineering Conference, 1999. (APSEC '99) Proceedings. Sixth Asia Pacific. pp. 154 – 161.
[18] Fred B. Schneider, “Implementing fault-tolerant services using the state machine approach: A tutorial,” ACM Computing Surveys 22, 4 (December 1990), pp.299-319.
[19] SCOTT SEELY, “SOAP: Cross Platform Web Service Development Using XML,” Prentice-Hall, Inc. 2002.
[20] Andreas Vogel and Keith Duddy, “JAVA Programming with CORBA,” John Wiley & Sons, Inc. 1998.
[21] Thomas Wolf and Alfred Strohmeier, “Fault Tolerance by Transparent Replication for Distributed Ada 95,” International Conference on Reliable Software Technologies - Ada-Europe'99, Santander, Spain, June 7-11 1999. pp.412-424.
[22] Ming-Jeng Yang, Yao-Ming Yeh and Yao-Ming Chang, ”Wireless Network Location Management with Quorum-based Systems,”
[23] Yeh Yao-ming, Sun Wen-Da and Chen Yeong-Sheng, “Object Replication and CORBA Fault-Tolerant Object Service,” Wu han University Journal of Natural Sciences, Vol.6, No.1-2, 2001, pp.268~277.