LYU0101

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LYU0101
Second semester FYP Presentation 20012002

• Wireless Digital Information System

Supervisor Prof. Michael Lyu
Yeung Kam Wah
Lam Yee Gordon
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Overview

• Introduction
• Design Direction
• System Architecture
• Client Implementation
• Server Implementation
• Work Done

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Introduction

• PDA become more popular
• Computation power and Memory is increasing
• High Bandwidth Wireless Technology
• BlueTooth, Wireless LAN
• 3G
• Demand for provide content to PDA
• Provide location related information

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Wireless Digital Information System

• To build a generic system that allow company
  provide their content to user
• Support different application
• Support multimedia content
• Same client program for different server
• Search function

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Wireless Digital Information System

• Usage
• Shopping guild in a Shopping Mall
• Information search in an Exhibition
• Showing vacancy in a Car Park
• Digital video Library client

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Design Direction
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Design Direction

• Whats our goal? (in previous slide)
• Main Issues we need to concern
• Data (format, storage, types)
• Search Engine (vector,probabilistic model,
  indexing, ranking, relevance feedback)
• Platform (hand-held device)

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Concern 1Data

• Use XML as the primary data format
• To give our user a standard, feasible and
  extensible way to design the data structure
• separate the concern on the data and presentation
  of information
• Use XSL to change XML into information
• changes in module or client platform will not
  affect the data

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Concern 1Data

• Storing XML in Database
• Database provides us many useful services

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Concern 1Data

• Conversion between XML and Database
• Common Method
• Break down XML file into tree nodes and remember
  its children's node
• Need to have different schema
• Need to make use of DTD
• Our Method
• Break down XML file into tree nodes and remember
  the parent node.
• Only need one schema (parent id, node id, type,
  data)

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Concern 1Data
lt!ELEMENT author ( name, address )gt lt!ATTLIST author id ID REQUIREDgt lt!ELEMENT name(firstname?, lastname)gt lt!ELEMENT firstname(PCDATA)gt lt!ELEMENT lastname(PCDATA)gt lt!ELEMENT address ANY gt
A DTD definition
Visualization of DTD in Tree
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Concern 2 Searching

• Use Vector Model
• assign weight to index terms in queries and in
  XML file (from tf factor, term-frequency and idf
  factor, inverse document frequency)
• compute degree of similarity between each XML
  file and user query
• give ordering of XML file

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Concern 2 Searching

• A full inverted index is built.
• have a better ranking, e.g. search for ??, I
  prefer to have ?? in search result, rather than
  ???.
• can help in searching a whole phase.

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Concern 2 Searching

• Problem client may need only ten search results
  at a time, I cant send all the result to PDA
  client at a time !!!
• Solution NN-search Methods (R-tree, SS-tree,
  SR-tree, X-tree, MVP-tree, A-tree, VA-file)
• We choose VA-file

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Concern 2 Searching
VP-tree
A-tree
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Concern 2 Searching
VA-file
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Concern 2 Searching

• Reason for choosing VA-file
• performs much better than the others in
  high-dimension space(as number of index term may
  be over thousand)
• IO page, number of Vector calculation, CPU time
  in search
• CPU time on construction

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Concern 3 Client Platform

• We choose Pocket PC as our client platform
• Reason
• Pocket PC have better support in
• Internet
• Multi-Media
• Performance
• processing power of Pocket PC is higher than
  Palm OS nowadays

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System Architecture
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System Architecture
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System Architecture

• Server side
• XML Data is processed and stored in the database
• A set of XSL is used to format the output
• Client side
• Display information
• Send user requests to server

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Server Side

• Four main components at Server Side
• XML Pre-processor
• Search Engine
• XSL transformer
• TCP Server that Communicate with PDA client
• incoming Keyword search, Map search result, XSL
  and XML set
• outgoing HTML, Video xml definition (probably a
  very simple SMIL), Map xml definition
• Web server (images)
• MMS server (videos)

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XML Pre-processor
Vector and VA-file Builder
Vectors and VA-file
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The PDA Client
server
PDA Client
Control Component
Main Window
Image Window
Video Window
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The PDA Client

• Main Window
• HTML Viewer
• Supported by system provided DLL
• Interface for information displaying
• User event will pass to control component to
  handle

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The PDA Client

• Image Window
• Using to display image
• Points highlight feature
• Using as query input interface, user can select a
  rectangular area as query input

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The PDA Client

• Video/Audio window
• Supported by system provided COM Object
• Display video to user

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The PDA Client

• Why using HTML viewer as main interface
• Provide feasibility to different servers using
  their own interface
• HTML is widely used and designed for display
  information.
• Why using system provide library
• Simplify the program and slim the program size
• These component is optimized

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Work Done and Possible Extension
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Work Done

• 2001 July Aug
• Study different wireless network
• Study different PDA platform
• Build a trial application on Pocket PC
• 2001 Sep Dec
• Design the application and system architecture
• Build the Pocket PC client

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Work Done

• 2002 Jan April
• Study the searching algorithm
• Build the server
• Continue implement the Pocket PC client

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Q A Section