The SADIe Transcoding Platform


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The World Wide Web (Web) is a visually complex, dynamic, multimedia system that can be inaccessible to people with visual impairments. SADIe addresses this problem by using Semantic Web technologies to explicate implicit visual structures through a combination of an upper and lower ontology. By identifying elements within the Web page, in addition to the role that those elements play, accurate transcoding can be applied to a diverse range of Websites.

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  • Hideous and messy for screen reader users due to a lack of semantics.
  • Sighted users can identify areas due to look and feel and presentation. However, this is not explicitly defined within the HTML therefore screen readers cannot convey this information to users.
  • We’re not the first. Two camps of transcoding methods, each with weaknesses and strengths.
  • Briefly talk about identifying areas; ditching bits we don’t need and rearranging the rest.
  • Take visual rendering information, which provides implicit knowledge and make it explicit.
  • Menu references the cnnNavigation CSS. To create a consistent look and feel all Web pages reference the single cnnNavigation definition.
  • Upper Ontology: Controlled set of terms that are applicable to all sites. Website specific ontology interfaces the heterogeneous terms of the CSS to the controlled vocabulary of the upper ontology. This implicitly annotates the XHTML, of which there are multiple pages. Creates a hybrid approach. Single accurate annotation applicable to a large number of Web pages.
  • Note that SADIe:xx refers to our central upper ontology. All website ontologies will refer to this giving a consistent interface. Blue circles represent css classes on the CNN Website. Ontology is about semantics, not names. We can work out cnnNavigation is probably a menu. What does cnnT1 do? All we know is that it’s high priority therefore important. We can change names and the model still works.
  • User access page as usual but SADIe proxy sits between traffic. On returning page, the proxy matches an ontology to the page using the ontology database. Ontology is queried eg give me all the CSS classes that I can remove Transcode parses DOM looking for elements that reference the returned set of classes from the query and performs appropriate operations. Removebable elements removed, menu pushed to the bottom etc.
  • Users can enter Website into the form al la Google
  • More advanced users can refine the transcoding options
  • We can link a Website to the transcoder. Give users a link for different versions. No additional overhead for developers.
  • SADIe’s great and just works.
  • The SADIe Transcoding Platform

    1. 1. The SADIe Transcoding Platform Darren Lunn, Sean Bechhofer and Simon Harper The University of Manchester School of Computer Science
    2. 2. The Web <ul><li>Designed with a focus on presenting information in a visual manner </li></ul><ul><ul><li>Images </li></ul></ul><ul><ul><li>Columned Layout </li></ul></ul><ul><ul><li>Chunks </li></ul></ul><ul><li>Some knowledge is only available implicitly from how the page looks </li></ul><ul><li>Can be difficult to access for users of screen readers </li></ul>
    3. 3. Implicit Knowledge = Advertisement = Banner = Main Content = Menu
    4. 4. Transcoding <ul><li>The adaptation of Web content to suit the needs of the browsing device </li></ul><ul><li>Heuristic Transcoding </li></ul><ul><ul><li>Uses rules / patterns </li></ul></ul><ul><ul><li>Can adapt a large number of pages </li></ul></ul><ul><ul><li>Can suffer from reduced accuracy issues </li></ul></ul><ul><li>Semantic Transcoding </li></ul><ul><ul><li>Uses annotations </li></ul></ul><ul><ul><li>Accurate adaptations </li></ul></ul><ul><ul><li>Time Consuming As Every Page Is Annotated </li></ul></ul>
    5. 5. SADIe in Action Image Advertisement Tabs Banner Main Menu Banner Headline Story Overview Main Story Story Overview Headline Main Story
    6. 6. SADIe Approach <ul><li>The visual rendering of a Web element informs the user of its purpose </li></ul><ul><li>The CSS defines the visual rendering </li></ul><ul><li>Identifying the purpose of a CSS definition implicitly identifies the purpose of the Web element </li></ul>
    7. 7. Exploiting CSS cnnNavigation{ float:left; border-width:0 1px 0 0; border-style:solid; . . . } CSS <ul class=&quot;cnnNavigation&quot;> <li><a href=&quot;/&quot;>Home</a></li> <li><a href=&quot;/WORLD/&quot;>World</a></li> <li><a href=&quot;/US/&quot;>U.S.</a></li> . . . </ul> (X)HTML
    8. 8. Annotation Through Ontology Upper Ontology . . . (X)HTML (X)HTML (X)HTML . . . CSS CSS CSS . . . Website Ontology
    9. 9. CNN (Partial) Ontology
    10. 10. Transcoding Architecture SADIe Proxy Web Page Identify Ontology Query Ontology Transcode Web page User
    11. 11. Basic User Interface
    12. 12. Advanced User Interface
    13. 13. Incorporated Into Website
    14. 14. Conclusions <ul><li>SADIe combines the benefits of both Heuristic and Semantic Transcoding </li></ul><ul><li>Annotation occurs at the CSS level using an ontology </li></ul><ul><li>One annotation propagates to all pages within the Website </li></ul><ul><li>Transcoding is achieved via a proxy </li></ul><ul><li>SADIe can be instigated via a User interface or embedded within a page </li></ul>
    15. 15. Questions?