線上即時訊息系統之研究

Abstract

本篇論文介紹線上即時訊息系統的基本模組，並介紹系統所提供之服務及其兩種運作模式 ─ 擷取模式及訂閱模式，擷取模式有反應時間過慢的缺點，而訂閱模式有連線數目過多的缺點。 本論文提出一種新的運作模式 ─ 混合模式，來改善上述之缺點。然後我們會研究及探討線上即時訊息系統在設計上與實作上需注意的要點，及可能會遇到的問題和解決方式。最後，我們設計並實作出一套線上即時訊息軟體，藉以測試系統在各種運作模式下的效果及效能。

In this thesis, we introduce the basic models of presence and instant messaging systems, and introduce the services and two kinds of operating models ─ the fetching model and the subscribing model. The fetching model has a drawback of slowly response time, and the subscribing model has a drawback of too many connections. In this thesis, we propose a new kind of operating model ─ the hybrid model, which we can use less connections while retaining fast response time. Then, we will research and discuss some design and implementation issues. Finally, we design and implement a messenger to investigate the feasibility and test the performance.