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Context-Aware Computing Applications
Bill Schilit, Norman Adams, and Roy Want
One-line summary: A context-aware system is one that can
determine and react to the current physical and computing context of mobile
users and devices, by altering the information presented to users or
commands issued by and on behalf of those users.
- Context-aware computing focuses on mobile-computing in which
mobile people and not just mobile computers are considered.
A context-aware system adapts according to location of use,
neighboring entities, accessible devices, and changes to all of these.
- Four categories of context-aware applications are presented as two
orthogonal axis with two points each: fetching information
vs. giving commands, and manual vs. automatic actions.
- Proximate selection: this is the manual fetching of
context-aware information about input/output devices,
non-physical objects and services, or locations. UI
issues of how to emphasize information based on degree of
- Automatic contextual reconfiguration: this is the
automatic selection of information or altering
components based on context. For example, a white-board
app may bring up
new or existing pages when a person enters a new room, or
an OS may decide to spin down a disk when AC power is
- Contextual information and commands: queries on
information or commands themselves may be altered by the
context of the user. For example, a migrate button could
bring a user's X display to a whiteboard in that user's
current room. Or, a whiteboard may display information
relevant to a user because it detected the proximity of
- Context-triggered actions: these are IF-THEN style
rules triggered by contextual information. For example, a
watchdog application will execute arbitrary UNIX shell
commands based on rules such as "if coffee is made
then play the rooster.au sound". A contextual
reminder program raises reminders when a contextual rule
is satisfied, like "the next time I see marvin" or
"the next time I'm in the library".
This work is part of the visionary ubiquitous computing program at Xerox
PARC. The GloMop research can be thought of as concentrating on a subset
of this framework, specifically the automatic and manual reconfiguration of
computing elements based on the current computing/network context or state.
- A host of difficulties exist with this framework, such as privacy
issues, authentication and security, deciding on the granularity of
context changes to recognize or act upon, UI issues for weighting
proximity information, networking and OS support for this
distribution system spanning many different networking media and
computing hosts, etc. Most of these issues are raised but not
addressed in the paper.
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