Adaptive Object Inclusion in AHA!

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Adaptive Object Inclusion in AHA!

• Paul De Bra
• Ad Aerts
• Bart Berden
• Barend de Lange

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Topics

• The AHA! Project
• Adaptive Object Inclusion
• Stable Presentations
• Conclusions / Future Work

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The AHA! Project

• AHA! Adaptive Hypermedia Architecture
• Open Source project, Web-based adaptive engine
• Built on Java Servlet technology, XML and XHTML
• General-purpose user-model and adaptation rules
• Data storage (domain, adaptation, user model)
  using XML files or mySQL database
• High-level authoring of domain- and adaptation
  model through Java Applets
• Compilers from authoring to engine structures

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Main AHA! Engine Features

• AHA! mainly reacts to page accesses
• Each resource (page) is associated with a concept
• The access event triggers rules that update
  attributes of user model concepts
• Each attribute update may trigger more rules that
  update more attributes of more concepts
• Links in the requested page are annotated based
  on expressions on attribute values
• Fragments and objects are conditionally included
  based on expressions on attribute values

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Adaptive Object Inclusion

• Reasons for adaptive object inclusion
• prerequisite explanation (include when needed to
  understand concept)
• comparative or additional explanation (include
  when user is ready for it)
• choose between media items (text, audio, image,
  video)
• same object may be included in different pages
  having separate objects eliminates redundant
  copies

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Adaptive Object Inclusion in AHA!

• Adaptation Rules determine inclusion of objects
• casegroup works like a switch statement in C
  to decide which object to include
• the inclusion causes a new access event
  triggering the adaptation rules of the included
  object
• included objects can thus influence how object
  inclusion and link adaptation works for objects
  further down on the same page

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Potential Problems with Object Inclusion

• When an object is included in several pages or
  several times on a page
• each access to the object triggers adaptation
• the user may not recognize the adapted object or
  page when it is revisited
• When many objects are included on a page
• the page is difficult to author (many object
  tags)
• it is difficult for an author to remember what
  the (possible) contents of the page is

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Stable Presentations in AHA!

• Adaptation is less noticeable when it is done
  once, when the user first sees the object (or
  page)
• stable forever (one-time adaptation)
• stable for one session (adaptation reoccurs in
  the next session)
• stable as long as an expression remains true
  (stable until some threshold is reached)

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Handling Many Small Fragments

• AHA! 3.0 is backward compatible with AHA! 2.0
• conditional inclusion of fragments through if
  statements inside the page
• all possible variations are visible to the author
• the if statements cause pages not to be in
  standard xhtml
• conditionally included fragments do not generate
  an event (and thus do not generate any user model
  update)

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Conclusions / Future Work

• Object inclusion and stable presentations make
  AHA! a more versatile/powerful as an AHS
• Using these features effectively is not trivial
  for authors we need authoring tools that use
  high-level structures
• one such tool is an Interbook to AHA! compiler
  (but that does not use object inclusion or stable
  presentations yet because Interbook does not use
  them)
• more tools are being developed in the ADAPT
  project (101144-CP-1-2002-NL-MINERVA-MPP)