基於無線應用協定並具推播功能之行動網際網路應用開發平台

Abstract

我們提出一個基於無線應用協定並具推播功能之行動網際網路應用開發平台 － MAP。此平台是根據無線應用協定1.2版的標準所開發的，期能為身處在行動環境下的使用者提供更廣泛的服務。開發此平台的主要目標是要提供一個具有彈性、延展性，以及快速的應用開發環境，讓行動網際網路的應用服務能夠建置在此平台上。本平台包含四個主要元件之設計與實作：（1）可在個人手持式裝置上執行的無線應用協定微型瀏覽器，（2）在桌上型或筆記型電腦環境下使用的無線應用協定模擬器，（3）基於無線應用協定並具推播功能之代理閘道器 － MBL Gateway，以及（4）分散式行動代理人伺服器 － Wagent。此平台能夠讓行動使用者很方便地存取現有的資訊系統、企業內部網路及網際網路上的各種服務。它整合了行動代理人以及無線應用協定推播這兩大技術，將網際網路上的各項服務延伸到無線的環境中。此平台亦可以將緊急的訊息，例如重要新聞與股票漲跌等資訊，主動傳送到行動用戶的手持式裝置上，即時通知行動用戶。除此之外，為了展示此平台之多用途，我們也利用本平台開發出數項應用，如基於無線應用協定之入口網站、遠端遙控、電子郵件來信通知，以及行動影像播放程式等。我們也利用一個可以模擬真實網路流量的模型，對MBL Gateway做效能上的評估。實驗結果顯示MBL Gateway在平均反應時間上，的確較其他兩個參與評估的無線應用協定閘道器來得更有效率。在負載最大（有270個使用者同時存取閘道器）的情形下，MBL Gateway的平均反應時間比其他兩個閘道器分別減少25％與87％。

We propose a WAP-based and Push-enabled mobile Internet application platform, MAP, that was built according to WAP 1.2 specifications to provide extensive services for users in the mobile environment. The goal of this platform is to provide a flexible, scalable and rapid-service-creation environment for mobile Internet applications to dwell in. The MAP has four main components, which have been designed and implemented: (1) a WAP micro-browser for mobile devices, (2) a WAP simulator for desktops or notebooks, (3) a WAP Push proxy gateway－MBL Gateway, and (4) a distributed mobile agents server, Wagent. This platform enables mobile clients to access legacy information systems, Intranet and WWW services conveniently. It takes advantage of the benefits of the mobile agent paradigm and the WAP Push technologies to extend Internet services to wireless environments. It also enables to push critical information, such as news and stock prices to alert mobile users in real time. In addition, we have developed several sample applications, such as WAP Portal, WAP Remote Control, E-Mail Notification, and Mobile Video Player to illustrate the versatility of this platform. We also evaluate the performance of the MBL Gateway using a realistic traffic model. Experiment results show that the MBL Gateway is more efficient than the other two notable open source WAP gateways in term of average response time. The MBL Gateway reduces the average response time by 25﹪and 87﹪compared to the Standalone Kannel Gateway and Original Kannel Gateway under the highest load (270 request/sec when session arrival rateλ＝0.015).