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 Institute of Computer Science

Device Independence Access for the World-Wide Web

An area of interest of the Advanced Computing Systems team is how to minimize latency for content transfers and achieve fast access over low bandwidth links for thin clients. we are mainly target at developers of web technologies and users that access the web via lightweight devices (PDA's, mobile phones,etc). In order to achieve that functionality, we build a system that it is capable of serving appropriate content to various devices that access the web. The variety of devices that are currently capable of accessing the web is large and is still growing. Not all the devices used today have the same capabilities of handling and presenting all the available data of the web. For that reason we serve each device with appropriate content that it can handle and present to the user.

Content Transcoding and Selection techniques.

We use the technique of transcoding and the selection of the content in order to fit the content to the capabilities of each device. From the other hand the question that arises is "How do you know the capabilities of each device?". The capabilities and even some of preferences of user that handles the device are known becauses of the use of the CC/PP protocol. The CC/PP protocol delivers information to the content servers and proxies. This information includes the device capabilities (e.g hardware and software characteristics) and some user preferences. Similar information is transferred with the HTTP protocol through the User-Agent and Access fields. The CC/PP protocol intends to organise and structure this information through the use of XML and RDF languages.

This protocol can work with two different ways.

  • As a standalone protocol performing separately from the HTTP and
  • work within the HTTP protocol as described in the HTTP-ex framework

In our system we follow the second approach of embedding the CC/PP information into the HTTP through the addition of extra header fields.

The transcoding from the other hand we decided that it can be performed in the server or proxy level of the client-server comunication workflow. The data included from the new CC/PP header called Profile had to be appropriately retrieved from the server or proxy respectively. According to that need and the tools that we used we implemented a new CC/PP module for the Apache Web Server. Details of how we implemented that module you can find at an old document that we had written when we were still in the development stage (ccpp_position.pdf).

To download and install the module to the Apache server you can visit the:

 

Demo Pages

In order to see the module working we have installed two CC/PP aware Apache servers (1.x , 2.x).
Below you can see a demonstration of this module's operation:

 

Final Edition

There is a final edition of our module mod_ccpp. This module provides appropriate content both for mobile devices (gif image files, amr audio files and 3gp video files) and Pocket Pc devices (gif image files, mp3 audio files and mpeg video files). This version works under win32 platform.

To download and install the module to the Apache Web Server (for windows) you can visit the:

Also, you can visit our demo web page for this edition (This page was demonstrated in the final review of Question How project which took place at Brussels on September 16, 2003):

[TV over IP] demo page included

 

CCPP Application

There is a ccpp aware application for Pocket PC devices.

Tranfer the cab file to the Pocket Pc for the application to be installed.

You need to have .NET Compact Framework installed in the PocketPC Device.

People

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This activity was partly supported by grant IST-2000-28767 from the European Union's Information Society Programme to the Question How project.

 
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