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Semantic Annotation for Web Content Adaptation

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Title: Semantic Annotation for Web Content Adaptation


1
Semantic Annotation forWeb Content Adaptation
  • Unit 14 of Spinning the Semantic Web

2
Introduction
  • Necessary for Web contents to be adapted for
    transparent access from a variety of client
    agents (cellular phones, PDA)
  • A large, full-color image may be reduced with
    regard to size and color depth, removing
    unimportant portions of the content, when
    accessed by certain devices
  • Better presentation and faster delivery to client
    devices
  • Transcoding transformation of information from
    one form to another
  • Web content transcoding
  • Crucial for universal Web access under varying
    conditions that may depend on client
    capabilities, network connectivity, or user
    preferences

3
Composite Capabilities/ Preferences Profiles
(CC/PP)
4
Introduction
  • CC/PP stands for Composite Capabilities/Preference
    s Profile, and is a system for expressing device
    capabilities and user preferences.
  • The goal of the CC/PP framework is to specify how
    client devices express their capabilities and
    preferences (the user agent profile) to the
    server that originates content (the origin
    server). The origin server uses the "user agent
    profile" to produce and deliver content
    appropriate to the client device. In addition to
    computer-based client devices, particular
    attention is being paid to other kinds of devices
    such as mobile phones.

5
Devices
  • The web is accessed by various devices
  • PC, NoteBook, PDA, Mobile Phone
  • Each one having different capabilities
  • Hardwarescreen size/color, audio, bandwidth
  • Softwarempeg, mp3, 3GPP, AMR

6
CC/PP RDF
  • The CC/PP framework starts with RDF and then
    overlays a CC/PP-defined set of semantics that
    describe profiles.
  • CC/PP, RDF based profiler, is a collection of
    information of capabilities of hardware platform
    and system software, and preferences of the user.

7
Advantages of CC/PP
  • By only sending required content, no time or
    bandwidth is wasted sending unwanted content.
    This can also lead to faster page loading times.
  • A server can provide information to a more
    diverse range on browsers. This can not only be
    beneficial in economic terms, but also in terms
    of site accessibility.
  • You give the users what they want, not what you
    think they want.
  • So many

8
Deployment(Client Server Proxies)
9
Deployment (Server Proxy only)
10
Deployment (Client Proxy only)
11
Deployment (Ideal Approach)
12
CC/PP Query
13
Content adaptation
14
Two ways to use CC/PP profiles
  • Selection
  • If the web server has a set of pre-written web
    pages, suitable for a number of different
    devices, then the profile can be used to decide
    which of these pre-written pages is most suitable
    for the web browser.
  • Transformation
  • Web page content can be kept in a neutral format
    (e.g. XML). This can then be transformed into an
    appropriate format, using the profile to decide
    what that format is.

15
CC/PP Implementations
  • DICE
  • Hewlett Packard
  • DELI
  • Intel
  • Inria
  • Keio University - Portal
  • UMBC
  • JIGSAW
  • X-Smiles Browser
  • So many

16
Demonstrations
  • An example of RDF file and graph
  • A Demo Page presenting the functionality of the
    CC/PP protocol

17
Reference
  • http//www.w3c.org
  • http//www.w3.org
  • http//www.webstandards.org
  • http//www.ccpp.org/
  • http//dice.ccpp.info/
  • http//www.tml.hut.fi/Opinnot/Tik-111.590/2000/Pap
    ers/Rdf.html
  • http//castrato.ics.forth.gr/qh/
  • http//www.csse.monash.edu.au/projects/MobileCompo
    nents/projects/pda_doc_layout/seminar-html/

18
External Annotation Framework
19
Annotation Schemes
  • Inline annotation embed annotations in a Web
    document
  • Created as extra attributes of document elements
  • HTML browsers ignore unknown attributes in a HTML
    document
  • Ease of annotation maintenance, eliminating the
    bookkeeping task annotations with their target
    documents
  • Require annotators to have document ownership
  • External annotation separate annotation from the
    original document
  • Raise no issues related to document ownership
  • Facilitate the sharing and reuse of annotations
    across documents
  • Avoid the mixing of contents and metadata

20
Applications of Web Content Annotation
  • Discovery
  • Accurate searches of Web resources
  • Qualification
  • Descriptions of users preferences regarding
    privacy
  • Adaptation the focus of this unit

21
Overview of An Annotation-Based Transcoding
22
External Annotation Files
  • Contain metadata that address a part of a
    document to be annotated
  • XPath and XPointer are used to associate
    annotated portions of a document with annotating
    descriptions
  • A reference may point to a single element or a
    range of elements
  • If a target element has an ID attribute, the
    attribute can be used for direct addressing with
    the need for a long path expression
  • Use RDF as the fundamental syntax of annotation
    files
  • User preferences and device capability Composite
    Capability/Preference Profiles (CC/PP)
  • Document profiles (http//www.w3.org/TR/xhtml-prof
    -req/)

23
Framework of External Annotation
24
Association
  • How to select an annotation file for a Web
    document
  • Implicitly ? by means of a structural analysis of
    the subject document
  • Explicitly ? by means of ltlinkgt tag
  • An annotation file can be associated with a
    single document file, but the relation is not
    limited to one-to-one
  • Many annotation files for one Web document
  • One annotation file for multiple Web documents
  • Useful when it is necessary to annotate common
    parts of Web documents, such as page headers,
    company logo images, and sidebar menus

25
Annotation-Based Transcoding System
26
Overview
  • Content can be adapted on a content server, a
    proxy, or a client terminal
  • An adaptation engine should not be forced to
    reside in any particular location
  • Use a proxy-based approach for content adaptation

27
Transcoding Architecture
  • Intermediary
  • Computational entities that reside along the Web
    transaction path
  • Facilitate an approach to making ordinary
    information streams into smart streams that
    enhance the quality of communication
  • An intermediary processor or a transcoding proxy
    can operate on a document to be delivered and
    transform the contents with reference to
    associated annotation files

28
Authoring-Time Transcoding
  • Requirement for authoring-time transcoding
  • WYSIWYG editor
  • Let the annotator to navigate from an existing
    annotation to a portion of an annotated document
    designated by XPath / Xpointer
  • Verify the results of content adaptation through
    a previewer
  • Authoring-time transcoding is crucial when
    annotations are employed for content adaptation,
    rather than discovery or qualification of
    contents
  • Content adaptation often changes the structure of
    original documents as the results of transcoding

29
Authoring-Time Transcoding
30
WYSIWYG Annotation Tool
31
HTML Page Splitting for Small-Screen Devices
32
Annotation Vocabulary
  • An annotation vocabulary for HTML page splitting
    needs to be specified to constrain the
    possibilities for decomposition, combination, and
    partial replacement of contents
  • Annotation of Web Content for Transcoding
  • Alternatives
  • Provide alternative representations of a document
    or any set of its elements
  • Color image ? grayscale image
  • A transcoding proxy selects the alternative that
    best suits the capabilities of the requested
    client device
  • Elements in the annotated document can then be
    altered either by replacement or by on-demand
    conversion

33
Annotation Vocabulary (Cont.)
  • Splitting Hints
  • An HTML file that can be shown as a single page
    on a normal desktop PC may be divided into
    multiple pages on clients with smaller display
    screens
  • pcdGroup specifies a set of elements to be
    considered as a logical unit and provides hints
    for determining appropriate page break points
  • Selection Criteria
  • Help a transcoding module select, from
    alternatives, the one that best suits the client
    device
  • pcd role ? value attribute (proper content, side
    menu, decoration)
  • pcdimportance ? priority (low important content
    may be ignored or displayed in a smaller font)

34
Annotation Descriptions
35
Adaptation Engine
  • Run on an intermediary server called WBI
  • Flow chart
  • Upon receipt of the request from a client
    browser, an original page is retrieved for the
    first time from a content server.
  • The editor component of the plugin tries to find
    the locations of annotation files
  • If it is specified in a link element in an HTML
    header section, retrieve the designated
    annotation file.
  • Lookup in a table for the mapping between an URL
    of the original page and that of an annotation.
    If it is found, retrieve the designated
    annotation file.
  • Otherwise, the original page is returned as it is
    and the session is terminated.

36
Adaptation Engine (Cont.)
  • Flow Chart (Cont.)
  • The generator component of the plugin generates a
    current page to be returned.
  • Taking account of client capabilities included in
    an HTML request header, the generator extracts a
    portion of a document object tree and returns a
    sub-tree to the client

37
Adaptation Engine System Flow
38
Application to Real-Life HTML Pages
  • The Web page used as an example is a news page
    from a corporate Web site
  • The news page consists of three tables stacked
    from top to bottom.
  • The top and middle tables correspond respectively
    to a header menu and a search form.
  • The bottom table is used for layouting.

39
Layout of A Real-Life News Page
40
Annotations for Splitting the News Page
41
Annotation for fragmentation of an actual news
page
42
Screen copy of a small display preview on an
authoring tool
43
Comparison of display contents on a small-screen
device
44
Splitting Result
  • The page splitting not only reduces the content
    to be delivered, but also places the primary
    content near the top of the fragmented page that
    is provides with navigational features
  • Placing navigational features (menu bars etc.)
    near the top of pages
  • Placing key information at the top of pages
  • Reducing the amount of information on the page
  • page fragmentation based on semantic annotation
    will be more appropriate than page transformation
    done by solely syntactic information (removing
    white spaces, shrinking or removing images)
  • Semantic rearrangement is one of the critical
    limitations of the syntactic transformation
    approach.
  • The navigational features achieved by this
    semantic annotation are noteworthy from the
    perspective of Web content accessibility.

45
Issues
  • Consistency between an Original Document and Its
    Annotation
  • Necessary to provide a way of keeping them
    synchronized
  • Extensibility
  • Custom-tailored transcoding module that runs
    without any external meta-information.
  • Using a general-purpose transformation engine,
    such as XSLT, which employs externally provided
    transformation rules
  • Task-specific ? semantics
  • Roles such as header, auxiliary, and layouter
    supplement semantics that cannot be fully
    prescribed in the definitions of Web document

46
Comparison of transcoding approaches in terms of
extensibility
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