The Context Toolkit

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The Context Toolkit

• A toolkit approach to providing support for
  Context-Aware Application Development

Presentation By John Bodily
The Context Toolkit was Developed At Georgia Tech
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..but before we start..

• A few questions
• What is a context-aware application?
• What are the characteristics of a context-aware
  application?
• Is context easy to use in practice?

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What is a context-aware application?

• According to the makers of the context toolkit
• We define applications that use context to
  provide task-relevant information and/or services
  to a user to be context-aware. 1
• Another Definition
• Such context aware systems adapt according to
  location of use, the collection of nearby people,
  hosts, accessible devices, as well as to changes
  to such things over time. 2

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Characteristics of a context-aware application

• Integrated Sensors
• Computing done in a distributed fashion
  (fixed/mobile)
• Adaptation to context

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Context, is it easy to use?

• In practice no
• No agreement on how to handle context data
• Unconventional acquisition sensors
• Distributed sources
• Fluctuating context and environment

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How can we make using context easier?

• Georgia Tech solution
• The Context Toolkit

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The Context Toolkit

• We have built an Architecture, the Context
  Toolkit, that contains a combination of features
  and abstractions to support context-aware
  application builders.3 Anind Dey
  

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Context Toolkit Features

• Context information can be accessed remotely over
  a network
• Platform independence
• Interpretation of context
• Aggregation of context
• Independence and persistence of context widgets
• Storage of a context history
• Separation of concerns

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User input vs. Context Input

• Similarities
• Input from several possibly heterogeneous
  devices.
• Need for abstraction of hardware details.
• Desire for reuse.
• Differences
• Context information must be collected from
  distributed sources
• Input not from user but the users environment

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Context Toolkit Infrastructure

• Context Widgets Basic building block, provides
  abstraction of sensor details.
• Context Servers Abstraction to provide
  aggregation of context data from context widgets
• Context Interpreter Takes input from context
  widgets and outputs it in a way that a set of
  applications can use.

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Context Widget

• Abstracts sensor details.
• Provides a common paradigm for context-aware
  applications.
• Allows reuse of code and persistence.
• Tailors sensor information to the needs of the
  application.
• Have attributes and behaviors.

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How are they used?

• Applications use context widgets as follows
• Applications subscribe to widgets that they need
  data from, a widget could be local or remote.
• Widgets perform callbacks to the application when
  something interesting happens, passing data back
  to the application in a form that the application
  requires.

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Example of a Widget
Table 1 Definitions of the IdentityPresence
widget. 3
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Another Example
Table 2. Attributes and callbacks of the Activity
Widget 3
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Other Widgets

• Server Widget A widget that provides
  aggregation of context data by subscribing to
  several widgets. The application the subscribes
  to the server and can get all the data it needs
  from one source.

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Other Widgets Continued..

• Interpreter Widget A widget that takes
  low-level input from another widget processes it
  and outputs reformatted data when certain
  conditions that an application is interested in
  are met.

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Applications

• In/Out Board Uses IdentityPresence
• Information Display
• DUMMBO Whiteboard capture and access

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So.what doesnt it support?

• No support for context sources that provide
  constant data
• No support for dealing with sensor failure
• No transparent access to distributed components

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References

• A Context-Based Infrastructure for Smart
  Environments, Anind K. Dey, Daniel Salber and
  Gregory D. Abowd. In the Proceedings of the 1st
  International Workshop on Managing Interactions
  in Smart Environments (MANSE 99), Dublin,
  Ireland, December 13-14, 1999. pp. 114-128.
• Context-Aware Computing Applications, Bill
  Schmidt, Norman Adams, Roy Want 1995, IEEE
• The Context Toolkit Aiding the Development of
  Context-Enabled Applications, Daniel Salber,
  Anind K. Dey and Gregory D. Abowd. In the
  Proceedings of the 1999 Conference on Human
  Factors in Computing Systems (CHI '99),
  Pittsburgh, PA, May 15-20, 1999. pp. 434-441.