Modeling and Using Context in Adapting Applications to Pervasive Environments

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Modeling and Using Context in Adapting
Applications to Pervasive Environments

• Tarak Chaari, Dejene Ejigu,
• Frédérique Laforest and Vasile-Marian Scuturici

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OUTLINE

• Introduction
• The scope of this paper
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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What is context?

• Fuzzy and general word
• Where are we? What we are doing?
• 1996, Browns definition
• Location, identity, application and time
• 2001, Deys definition
• Any information characterizing an entity
• An entity is a person, a location, an object
• The most general and adopted definition
• Too vague and it does not help modelling the
  context

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context definition and properties

• Definition context is the set of external
  parameters that can modify the behaviour of an
  application by defining new views on its data and
  services
• Wingorad something is context because of the way
  it is used in interpretation, not due to its
  inherent properties
• Example GPS coordinates in a healthcare
  application / in traffic regulation application
• Context parameters are transparent to the user
• New instance new contextual situation
• These precisions help adding context awareness
  to non adapted application

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Context Awareness

• Definition
• The ability of acquiring context knowledge
• adaptation to the context change
• Requirements
• Capture
• Interpret
• Store/Disseminate
• Adapt

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Motivations

• Existing solutions
• specific to particular concerns
• a lot of interest on how to capture context
• Lack of a comprehensive context model
• formality
• expressiveness
• Lack of a concrete approach to adapt applications
  to context
• generic adaptation strategy
• dynamic adaptation

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OUTLINE

• Introduction
• The scope of this paper
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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SECAS Project

• Simple Environment for Context Aware Systems
• Generic and comprehensive platform
• Creating new context-aware applications
• Adapting existing legacy applications to new
  contexts

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SECAS Architecture
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OUTLINE

• Introduction
• The scope of this paper
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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Context Modeling

• Context (Subject, Predicate, Value, Time,
  Certainty)
• Example (Bob, isLocatedIn, room305,
  Fri-23-jun-2006-120000-GMT, 0.85)
• Intelligence and semantics processing
• (VideoService, runsOn, PDA-01)
• (PDA-02, runs, VideoService)
• (realPlayer, runsOn, laptop-01)
• ? devices that can run Video Services

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Ontology for context modeling
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Example of a context ontology
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OUTLINE

• Introduction
• The scope of this paper
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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Applications Functional Model

• Functional Model application services
  description services dependences
• XML deployment descriptor (extension of pnml)

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Service Adaptation strategy
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Service adaptation entity

• Adapter (proxy)

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Service adaptation rules

• Pairs (context situation, adaptation action)
• Context situation Logical expressions of
  context predicates
• Adaptation action a list of adaptation
  operators
• Operators on the functional model
• Operators on the inputs and outputs of services
• Operators on service versions
• Example

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OUTLINE

• Introduction
• The scope of this work
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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SECAS Administration User Interface
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Context1 Doctor1 using SICOM on a standard PC
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Context2 Doctor1 using SICOM on a smartPhone

• E1 E2
  E3 E4
• E5 E6
  E6

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OUTLINE

• Introduction
• The scope of this paper
• Context Modeling
• Adaptation strategy to context
• Implementation
• Conclusions

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Conclusions

• A comprehensive Context model based on ontology
  representation
• An extensible adaptation platform to
• create context aware applications
• adapt existing applications to context
• Platform under development
• Services adaptation module completed and
  validated
• Content adaptation module
• User interface adaptation module

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Question time !

• ?