The document describes an infrastructure for managing context information from mobile devices and making it available to applications and services. The infrastructure includes a context manager that stores current and historical context data and allows providers to supply context and consumers to access it. An implementation of the infrastructure was tested at varying scales and showed it could support multiple concurrent providers and consumers, though performance issues arose with large amounts of context data or high numbers of participants. Future work is needed to further optimize performance and add security and privacy capabilities.

1. An Infrastructure to Provide Context-Aware
Information and Services to Mobile Users
UCAmI 2012
Pablo Curiel, Ana B. Lago
DeustoTech - Deusto Institute of Technology, University of Deusto
http://www.morelab.deusto.es
December 4, 2012
Infrastructure to Provide Context-Aware… 1/26

2. Outline
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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3. Introduction
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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4. Mobile devices’ ecosystem
► Mobile devices play a prominent role in our lives.
►6 cellular subscriptions for every 7 people in the world.
► Emergence of the Smartphones
► Powerful hardware
► Permanent connectivity
► Equipped with numerous sensors
► Ability to execute a great diversity of applications
► Provide richer and better context information than ever
before
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5. The Objective
► Build an infrastructure which
► Manages the context information in mobile environments
► Makes it available for the rest of the entities in the
environment
► Enable
► The provision of relevant information and services to end-
users.
► Mobile application and services to adapt their behaviour to
meet user needs.
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6. The Infrastructure
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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7. Infrastructure
► The context management infrastructure…
Context Manager
Context Broker
Consumers
Providers
Context
Context
Query Subscription
Manager Manager
Current Context
Context History
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8. Providers
► Entities which provide context information to
Providers
the system
Context
► Physical sensors, end-user mobile devices,
social networks, mobile services, etc.
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9. Consumers
Entities that make use of context information
Consumers
►
Context
to adapt their behaviour or to take decisions
► Mobile application and services
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10. The Context Manager
► Central element
Context Manager
► Context repository
► Stores the context information Context Broker
retrieved from the sources Query Subscription
Manager Manager
► Allows consumers to access it
► Data-centric approach
► Comprised of various independent
Current Context
components Context History
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11. The Context Manager
► Current Context
► Stores the context information which is valid in
each moment
Current
► Follows the ontological model shared by the Context
whole system.
► Context History
► Keeps track of the changes taken place in the
context information Context
History
► Storage policies
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12. The Context Manager
► Context Broker.
► Manages access to current and
history context repositories.
► Receives context information from
Context Broker
the sources and stores it in the
Query Subscription
current context Manager Manager
► Moves outdated information to the
context history
► Responds consumers’ requests
querying these two repositories
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13. The Context Manager
► Context Broker.
► Two subcomponents
► Query Manager Query
► Synchronous access Manager
► Subscription Manager
► Asynchronous access Subscription
Manager
► Register subscriptions and receive notifications
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14. Context Manager API
► Unique entry point to the Context Manager functionality
► Exposes methods that enable context source and
consumers to work with context information
► Query the context repositories
► Subscribe to context information changes
► Add/Remove context information
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15. Implementation
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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16. Implementation
► Java
► OSGi
► Jena2 and Jenabean
► RESTful API
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17. Evaluation
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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18. Starting scenario
► Suggest plans to friends depending on their location and
availability.
► Android end-user app ► Contextual service
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19. Tests design
► And starting from this scenario...
► Tests where
► The contextual service acts as context source, periodically
(every 5s) adding alerts for the end-user application
► The end-user application
► Queries periodically (every 1s) for these alerts
► Registers asynchronous subscriptions to receive them
► In each of these tests the number of context source and
consumers interacting with the context manager varies
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20. Tests results
► Effect of different number of concurrent sources
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21. Tests results
► Effect of different instance count in the current context
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22. Tests results
► Effect of different number of concurrent consumers
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23. Tests results
► Comparison between using Jena and Jena+Jenabean
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24. Conclusion
Introduction
The Infrastructure
Implementation
Evaluation
Conclusion
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25. Conclusions
► The implemented prototype and the tests carried out
have shown
►A functional system which complies with the defined
requirements
► Is extensible
► However, performance issues were observed
► The number of concurrent sources increases
► The context space held by the context manager grows
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26. Future Work
► Removing or replacing Jenabean
► Privacy and security policies
► Trustin context providers
► Control access for context consumers
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27. An Infrastructure to Provide Context-Aware
Information and Services to Mobile Users
Pablo Curiel
{pcuriel@deusto.es}
DeustoTech - Deusto Institute of Technology, University of Deusto
http://www.morelab.deusto.es
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