即時網頁應用伺服器推送架構

Abstract

本論文提出一個即時頻道推送架構，利用伺服器推送及鍵值資料庫技術，將一群個人電腦伺服器組成一個可以讓多個用戶端即時分享相同訊息。用戶端可以是瀏覽器或智慧型手機。當用戶端連線至網頁應用伺服器時，網頁應用伺服器會連結至即時頻道推送伺服器，即時頻道推送伺服器便會提供一個含有爪哇腳本語言的應用連線程式，瀏覽器利用此一連線程式，可以建立一個持續性且安全的的連線至即時伺服器推送系統中的資料頻道，以達到即時分享訊息的效果。智慧型手機利用連線程式直接連線並訂閱即時伺服器推送系統中的資料頻道。當新的訊息被推送到某一個特定的資料頻道時，此一訊息會被推送至所有訂閱於此一資料頻道的用戶端，進而達到達到同時收到相同的訊息。在企業應用上，即時頻道推送架構可以協助將傳統的網頁應用系統經由網頁服務應用介面的整合，轉換成一個可以即時分享的網頁應用系統。我們利用簡易的整合程序，完成一些整合應用系統範例，結果相當不錯。例如：整合谷歌地圖，建立一個即時地圖導引系統; 我們利用即時頻道推送架構，建立一個智慧型雙向簡訊系統，可以讓一群智慧型手機同時收到即時訊息。為了服務更多的同時連線用戶，從上千個至數十萬個同時連線用戶，我們設計一個可擴充的架構，可以利用多台個人電腦伺服器組成一個大型的即時頻道推送，實作的結果證明是可行的。

This dissertation presents a Real-Time Channel Push (RTCP) architecture, which applies Server Push and key-value database technologies in a pool of common PC servers, and thus enables many clients to share the same message real time. The clients can be browser or smart phone. When a client connects to a web 2.0 application which has an access to RTCP, the RTCP will provide the browser with a suitable JavaScript communication module to link it with RTCP persistently and securely. This module enables all browsers subscribed to the same RTCP data channel communicate with each other. In the aspect of smart phone application, it can direct access to RTCP data channel and communicate with all the browsers subscribed to the same RTCP data channel. When a message being pushed to this specified data channel, it is pushed to all subscribed clients and they will receive the same message at the same time. To enterprise application, RTCP architecture can help building a real-time intranet sharing environment via integrating the web 2.0 applications with RTCP server. Through simple web API, it is easy to convert web 2.0 applications into real-time sharing applications. Adopting the integration procedures, we have accomplished several web 2.0 integration applications and has demonstrated good results. For examples, we used RTCP solution as an interactive guide system for multiple browsers to share the same Google Maps location; we also used this solution as an intelligent Bi-Direction SMS[26] system on smart phone and send SMS to a group of users real time. In order to serve large amount of clients, i.e. from thousands up to hundreds of thousands of people, we designed an extensible RTCP architecture which could form a large RTCP system with many small PC servers. Experiment results have confirmed that the implementation of RTCP architecture is feasible.