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Context-Awareness on Mobile Devices – the Hydrogen Approach

Context-Awareness on Mobile Devices – the Hydrogen Approach. Sangkeun Lee. Context-Awareness for Mobile Devices. Support context-awareness for considering Special requirements of mobile devices regarding the limitations of network connections, computing power

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Context-Awareness on Mobile Devices – the Hydrogen Approach

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  1. Context-Awareness on Mobile Devices – the Hydrogen Approach Sangkeun Lee

  2. Context-Awareness for Mobile Devices • Support context-awareness for considering • Special requirements of mobile devices regarding the limitations of network connections, computing power • Requirements for an architecture of a framework to support context-awareness on mobile devices • Lightweightness • Extensibility • Robustness • Meta-Information • Context-Sharing • Separiting the concerns of context sensing from the application is needed

  3. Hydrogen Context-Framework • Three architecture • Application Layer • Management Layer : Context Server • Provide simple methods for the applications for retrieving or subsribing to a context • Adaptor Layer • Responsible to get information from sensors • Reusability, Exchangeability of sensors & adoptors

  4. Implementation – the Hydrogen Approach • Prototype Implementation • PersonalJavavirtual machines Jeode, J2ME, iPAQs, PocketPC 2002 • Context • Time, Location, Device, User, Network • ContextClient • Responsible for communication : open ports, queries data • Context Server • Java Executable object • Communication in two forms : XML-streams, serialized Java objects • Extensibility • toXML(), fromXML() • Open Issues • Comprehensive Context Model • XML Protocols • Context Sharing

  5. CASS- Middleware for Mobile Context-Aware Applications Sangkeun Lee

  6. General • CASS (Context-awareness sub-structure) • Server based extensibile middleware to support context-aware applications on mobile devices • High-level context data abstraction • Separation of context based inferences from application code • Configurable by users

  7. CASS Overview • Requirements • Support many of context sources • Provision for context history • Support for context interpretation • Support higher-level abstraction of contexts • Should be event-based, extensible framework • Transparent use of distributed sources of context • Separation of application procedure • Architecture • CASS Applications do not need to store low-level details of context sources and communicate with individual source • CASS Middleware does that • Design • SensorListener listens for updates and stores context information • ContextRetriever retrieves stored context • ChangeListener allows a mobile computer to listen for context events

  8. Data Management & Inference • CASS uses a database for persistent data store • The database is server-based that does not suffer from the storage space and performance • Data can be read and manipulated using SQL • Not only context, domain knowledge and rules can be stored too • Inference Engine • Forward Chaining

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