LYU0101 - PowerPoint PPT Presentation

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LYU0101

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Break down XML file into tree nodes and store as tuples (parent id, node id, type, data) ... MMS server (videos) XML Pre-processor. Vector and. VA-file Builder ... – PowerPoint PPT presentation

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Title: LYU0101


1
LYU0101
Second semester FYP Presentation 20012002
  • Wireless Digital Information System

Supervisor Prof. Michael Lyu
Yeung Kam Wah
Lam Yee Gordon
2
Overview
  • Introduction
  • Design Direction
  • System Architecture
  • Work Done
  • Possible Improvement

3
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

4
Wireless Digital Information System
  • To build a generic system that allow company
    provide their content to user
  • Support different application
  • Single client for different server
  • Search function
  • Support multimedia content

5
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

6
Design Direction
7
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)

8
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

9
Concern 1Data
  • Storing XML in Database
  • Database provides us many useful services, e.g.
    building different kinds of indexing on data,
    concurrency control, recoverability of data, etc.
  • Break down XML file into tree nodes and store as
    tuples (parent id, node id, type, data)
  • easy for locate and update the data in XML
  • reform the XML on need

10
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

11
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.

12
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 !!! (in decreasing of the
    similarity, just like have different result page
    in google)
  • NN-search Methods (R-tree, SS-tree, SR-tree,
    X-tree, MVP-tree, A-tree, VA-file)
  • We choose VA-file

13
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
  • Characteristics of VA-file
  • no MBRs, no Tree, use approximation linear
    search, just build a small filter file

14
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

15
System Architecture
16
System Architecture
17
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
  • Displace information
  • Send user request to server

18
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,
    ltXSL,XMLgt
  • outgoing HTML, Video xml definition (probably a
    very simple SMIL), Map xml definition
  • Web server (images)
  • MMS server (videos)

19
XML Pre-processor
Vector and VA-file Builder
Vectors and VA-file
20
The PDA Client
  • The four main components
  • Control component
  • Main window
  • Video window
  • Image window

21
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

22
The PDA Client
  • Video/Audio window
  • Supported by system provided COM Object
  • Display video to user
  • Image Window
  • Using to display image
  • Points highlight feature
  • Using as query input interface, user can select a
    rectangular area as query input

23
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 components
  • Simplify the program and slim the program size
  • These component is optimized

24
Work Done and Possible Improvement
25
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 Packet PC client

26
Work Done
  • 2002 Jan April
  • Study the searching algorithm
  • Build the server
  • Continue implement the Pocket PC client

27
Possible Improvement
  • At Server Side
  • relevance feedback (improvement on query)
  • caching (better performance)
  • At Client side
  • enhancement on the Main window, Image window and
    Video window

28
Q A Section
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