Modeling User Input and Hypermedia Dynamics in Hera

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Modeling User Input and Hypermedia Dynamics in
Hera

• Databases and Hypermedia Group

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Outline

• Modern WIS
• Hypermedia Dynamics
• Hera
• Modeling Dynamics in Hera (Example)
• Implementation
• Conclusion

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Modern WIS

• Have broad and heterogeneous audience
• Have typically distributed and heterogeneous data
  sources
• Provide complex services
• Adapt to concrete users, groups
• Adapt to concrete environments (communication
  channels, user devices)

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Hypermedia Dynamics

• What is the functionality of WIS, what services
  do they offer (business logic)
• How users interact with WIS, what is the
  navigation structure, how users input information
  (navigation structure)
• How users actions influence hypermedia
  presentation of WIS (e.g. personalization)

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Hera Methodology

• Model-driven methodology, defines design phases
• Conceptual Design that results in Conceptual
  Model (CM, describes data content used for
  generation of hypermedia presentations)
  construction
• Application Design that results in Application
  Model (AM, describes the navigation structure and
  functionality) construction
• Presentation Design that results in Presentation
  Model (PM, describes spatial layout and rendering
  of hypermedia presentations) construction

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Hera Models

• Fully specify dynamic hypermedia applications
  hence, there is no need of additional programming
• Are used by a generic Hera engine for generation
  of hypermedia application pages (by on-demand
  instantiations of model subsets)

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Conceptual Model

• Defines the data content in terms of RDFS
  (concepts, attributes, properties)

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Application Model

• Navigation structure of a hypermedia application
  on top of CM
• Hypermedia dynamics (navigation structure updates
  and application functionality) of a hypermedia
  application

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Navigation Structure in Application Model

• Navigation nodes (pages) specification in terms
  of slices (collections of concepts attributes to
  be displayed)
• Node composition in terms of slice aggregation
  relationships
• Navigation edges (hyperlinks) in terms of slice
  references

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Dynamics in Application Model

• User input specification in terms of Input Forms
• Application context (state) specification in
  terms of Application Context Model
• Context manipulation specification in terms of
  queries

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Application Context Model

• Extends CM with additional data structures needed
  for application functionality (to store
  application/navigation state, user inputs, user
  model, etc.)
• Example storing the user selection (shopping
  basket)

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Slices

• Meaningful collection of attributes of one or
  more related concepts
• Represent a presentation page or its part

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Input Forms

• Specify user data entries contain sets of input
  fields with
• Input method (selection from offered items, text
  input, etc.)
• How the offered items are created (for
  selections)
• Determine data manipulation operation associated
  with a form (form processing)

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AM Example
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Data Manipulations

• Update application context information
• Defined as SeRQL queries
• Used for processing forms (handle user input)
• Q1 creates instances of SelectedPainting
  according to the SelectForm form content

CONSTRUCT PltrdftypegtacmSelectedPaintinggt
FROM PltrdftypegtcmPainting
ltcmanamegtPaname WHERE Paname IN SELECT
Faname FROM SFltformanamegtFaname,
SFltrdfIDgtFormName
WHERE FormName SelectForm
creates
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Hera Architecture

• Defines how the models are used for automatic
  generation of hypermedia presentation

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Hera Implementation

• HPG 2.0 (Hera Presentation Generator, dynamic
  version) implemented in Java as a servlet
• Uses RDF API HP Jena for RDF data transformations
  based on RDFS models (CM, AM)
• Can use XForms processor
• Uses Sesame as main content repository and
  application context repository uses SeRQL/RQL as
  query languages
• Set of graphical tools for designers for CM and
  AM based on Visio

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Conclusion

• Advantages of Hera approach
• It is Model-driven leads to a good separation of
  concerns
• Uses Semantic Web specification languages models
  are flexible and have explicit semantics, easy to
  check for consistency and correctness
• No need of extra programming all aspects of a
  designed system are captured in high-level models

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Future Work

• Going towards higher level functional
  specification, e.g. rules instead of queries
• Using OWL (DL) model specification for higher
  expressive power and possibility of reasoning on
  models (consistency and correctness checking)
• Incorporating web services into WIS applications
• Using possible separate (configurable) Hera
  components, like adaptation component,
  presentation component in different legacy
  systems

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Questions?