臺灣博碩士論文加值系統

溝通是合作的開始，而合作則是解決複雜問題的基礎。這個觀念也同樣適用於分散式系統。在分散式的環境中，彼此分散的程式單元以某種方式來互相傳遞訊息，並以此為基礎來分工合作解決較複雜的問題。設計一個分散式系統所牽涉到的問題非常多，但如何設計一個彈性，可靠且有效率的通訊子系統對於分散式系統的整體設計而言則至關重要。因此，本論文主要探討如何實作出一個通訊模式讓彼此分散的程式單元以更有彈性的方式來傳遞訊息。

去耦且多對多的通訊方式非常適合作為分散式系統中各個程式單元間的通訊模式。因為去耦型通訊可以讓分散式系統中各個程式單元間的通訊不受限於空間，時間及各自的程式流程。而多對多的通訊方式則允許分散式系統中的各個程式單元同時進行一對多的通訊。在本論文，我們探討如何以Java RMI 實作出這個通訊模式。我們研究 OMG Event Service 規範，因為此規範描述了此種通訊模式的基本架構。此外，被傳送訊息的 expressiveness 可以受益於 XML
技術，因此我們也探討如何讓我們的實作能傳送由 XML 所標記的訊息。我們以 JAXP 為主，讓我們的訊息傳遞服務能傳送由 JAXP 所產生的 DOM 物件。

Communication is a beginning of collaboration, and collaboration is a foundation for successfully solving complex problems. The notion is also applied to distributed systems. In the distributed and loosely-coupled environment, the distributed program units communicate with each other through some way and hence can collaborate to accomplish some complex tasks. There are many design issues when constructing distributed applications, and how to design a flexible, reliable, and efficient communicating subsystem is crucial to the design of distributed system. In this thesis, we study how to implement a flexible communication model so that distributed program units can transmit messages in a flexible way.
Decoupling and many-to-many communication model are appropriate for communication between distributed program units. Since decoupling communication paradigm supports decoupled interaction in space, time and flow among distributed program units in the distributed system. Furthermore, many-to-many communication paradigm allows distributed program units to execute one-to-many communication simultaneously. In this thesis, we study how to implement the decoupling and many-to-many feature using Java RMI. We study the specification of OMG Event Service because the specification specifies the basic architecture that supports decoupling and many-to-many communication model. In addition, expressiveness of transmitted messages can benefit greatly from XML technology. Besides that, we also study how to integrate XML-messaging into the implementation. We focus on JAXP and intend to make DOM objects generated by JAXP to be transimited by the messaging service.

1 INTRODUCTION………………………………………………………1

2 DECOUPLING AND MANY-TO-MANY COMMUNICATION……………4

2.1 Communication aradigm………………………………………4

2.2 OMG Event Service……………………………………………8

2.2.1 Event Service Overview…………………………………8

2.2.2 Event Service Interface………………………………12

3 XML MESSAGE PROCESSING………………………………………23

3.1 XML Processing Architecture……………………………24

4 IMPLEMENTATION DETAILS………………………………………27

4.1 Architecture…………………………………………………29

4.2 Initializing Message Channel…………………………30

4.3 Establishing Connection…………………………………32

4.4 Propagating Messages………………………………………34

5 CONCLUSIONS………………………………………………………39

REFERENCES …………………………………………………………41

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