An Architecture for Adaptive Content Extraction in Wireless Networks Phil West Greg Foster Peter Clayton Submitted to the South African Telecommunications Networks & Applications Conference (SATNAC) 2005

Overview Scenario Proxy Server Spatial Representation Tag Extraction Personalization Monitoring Network Conditions Adaptive Extraction Architecture – Putting it all together Current Work

Scenario

Proxy Server Crunch 2.0 Open-source, Java project Thread-based proxy server Extensible Plugins using reflection Each plugin receives a DOM tree representation of the content Contains an extraction module Advertisements Plain text from HTML – For visually impaired users Link lists Empty tables

Spatial Representation Process: Parse HTML into DOM tree Render the nodes using ICEBrowser SDK Extract boundbox for each node Generate image based on coordinates Scaled to fit on PDA screen Create HMTL image map to allow navigation

Spatial Representation Issues Script Algorithm complexity Depth of trees Size of nodes Other approaches Use for special cases –Structured HTML/XML

Tag Extraction Extract rich content Simply replace tags with links Issues: May lose context – extracted content displayed in a new window

Personalization Server-side SQL database stores session preferences for each user –ipaddress; settings{spatial,video,sound,etc} Settings for each request them obtained from DB Client-side Default settings stored locally Browser Helper Object (BHO) as a plug-in for Internet Explorer BHO listens for navigate2 events Appends settings to request if (first request of session || settings have been altered)

Monitoring Network Conditions WinPcap – Windows Packet Capture Library Used to access network statistics Implemented a class in C++ Java Wrapper Class Exposes Native Methods Provides: Bytes per second Packets per second Also Track: Number of connections (in a defined time period)

Adaptive Extraction Load Testing Microsoft Application Centre Test Proxy Sniffer Created test web pages Load test these pages, accessed through the proxy server Content extracted at increasing levels of network usage 1 st : Video and sound 2 nd : Script 3 rd : Images Increase the number of possible simultaneous connections

Putting it all Together Adaptive Content Extraction Architecture

Putting it all Together Provides: Mark-up language, content extraction system for use with wireless networks Users have the ability to select only the content they desire Implications for pay-for-data billing schemes Functionality is provided to allow users to personalize their extraction settings Algorithm for automatically adapting extraction settings according to varying network conditions Preliminary results show this allows more users to access the network without losing performance 2 “real world” implementations

Current Work Adapting the approach for use with slide show presentations Will be presented at the 4 th World Conference on mLearning Functionality to annotate content Delta correction Usability study Investigating alternative HTML renderers For use with the spatial representation algorithm More in-depth testing of the adaptive system