Download - Exposing Semantics to Drive Transcoding
Exposing Semantics To
Drive Transcoding
Darren Lunn, Sean Bechhofer and
Simon Harper
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Summary
• Visual Rendering Can Provide Semantic Information
• Semantics Can Be Used to Drive a Transformation Process
• Poor Design Decisions Can Hinder Flexibility and Adoption
• A Well Defined Model and a Little Pragmatism Goes a Long Way
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The Web
• Focuses on Presenting Information in a
Visual Manner
– Images
– Columns
– Chunks
• Some Knowledge is only Available
Implicitly from the Page Rendering
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Implicit Knowledge
Advertisement
Banner
Menu
Main Content
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Assistive Technology
• Visually Impaired Users use Assistive
technologies e.g. Screen Readers
– Render Pages Sequentially in Audio
– Achieved by Accessing the Underlying HTML
• Focus on Visual Presentation Rather than
Content Hampers This
– Particularly if Attention is Not Paid to Coherent Design
– Subtleties of Visual Presentation Can be Lost
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Accessing CNN In Audio
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Screen Readers
• Traversal of Content is Serial– Top-to-bottom
– Left-to-Right
• Important Information may not be Encountered Until Later On.
• Information Such as Menus may be Repeated for Every Page– Tiresome if the User has to Wait for the Menu for Each
Page
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SADIe Approach
Banner
Banner
Menu
Headline Story Overview
Tabs
Advertisement
Image
Main Story
Heading
Story Overview
Main Story
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Original Annotation Solution
• Use an Ontology as an Abstraction to
represent Basic Concepts Appearing in
the Page
• Annotate the CSS Rather than the Page
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Proposed Solution
HTML
CSS
OntologyTransformed
Page
Rendered
Page
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Two-Part Ontology
• An Upper Ontology Provides Basic
Information about Authoring Concepts
• This is Extended to Provide information
about Particular Style Sheets
• The Definitions in these Ontologies
Provide the Annotation of the CSS
Elements
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Architecture
Application
HTMLCSS
Upper Ontology
Site-Specific Extension
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Overarching Aim
• Describe Semantic Structure of
Websites
• Use Inference Engines to Determine
Relationships Between Elements of the
Website
• Transcode Website Based on these
Relationships
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Success?
• Transcoding was Successful on a
Diverse Range of CSS-based Sites
• User Studies Demonstrated the
Usefulness of the Transformations
• But the Model had Weakness that
Limited The Approach
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Application Functionality vs.
Semantic Structure
SADIe
Removable NonRemovable
Priority Menu
Medium LowHigh
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Application Functionality vs.
Semantic Structure
Menu
Removable
High Priority
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Separate Functionality From
Domain Knowledge
• We Advocate Separation of Structure
(HTML) from Presentation (CSS)
• Also Separate Knowledge from
Application Functionality
– Split Ontology Into Two
– Push More Computation into the Application
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Why Separate
• Adds Flexibility to the Overall
Application
• Adds Flexibility to the Overall Approach
• Easier For Designers to Construct
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General Relationships
• CNN_AdBox is Contained Within a
2ColumnFloat
• 2ColumnFloat is Removable Therefore
CNN_AdBox is Removable
• What If CNN_AdBox is Not Removable?
<pclass=“2ColumnFloat”>
<divclass=“CNN_AdBox”>...</div>
</p>
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Class Containment
High Priority Removable
CNN_AdBox 2ColumnFloat
isContained Within
hasPriority isRemovable
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Only Within That Instance
• CNN_AdBox is Contained Within a
2ColumnFloat Only Within this Instance
• CSS Properties Can Still be Applied
Even If CNN_AdBox is Not Contained
Within 2ColumnFloat
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A Little Testing Goes A Long
Way
• Small Scale Testing Brings to Light
Errors of Modelling
• Can not Expect To Know Everything
Without Real World Case Studies
• Prevents Effort of Reengineering
• Prevents Loss of Faith in the Tool
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Be Pragmatic
• Designers are Not Ontology Engineers
• Significant Overhead Will Hinder
Adoption
• Balance Between Minimal Effort but
Enough Knowledge to not be Hindered
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New SADIe Architecture
Application
HTMLCSS
Structural Ontology
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CSS Role Property
• Add a New Role to the CSS
• Still Validates
• Explicitly States What the Class Represents
• Values Based on WAfA Ontology– Ontology of Accessibility and Web Authoring Concepts
2ColumnFloat{
-uom-structural-role:LinkedMenu;
...
}
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Benefits
• Less Overhead to Expose Semantics
• Non Destructive
• Still Provide Same Functionality
– New Transformations being Investigated
• Other Uses of the Exposed Semantics
– AiSC
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Conclusion
• Visual Rendering Can Provide Semantic Information
• Semantics Can Be Used to Drive a Transformation Process
• Poor Design Decisions Can Hinder Flexibility and Adoption
• A Well Defined Model and a Little Pragmatism Goes a Long Way
