Context and Context-

mashpeemoveMobile - Wireless

Nov 24, 2013 (3 years and 9 months ago)

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Context and Context
-
Aware Computing

Omar Khan

CS260, Fall 2006

Background


Ubiquitous computing in early 90s:
computing everywhere and “
invisible



Implication


Create applications that work seamlessly in
human environments


Understanding of
context


Olivetti Active Badges


Problem:
locating

researchers


Solution: badge tied to identity, tracked as
researcher moves in building





[Want and Hopper, 1992]

Assistant sees this view


-

knows where researcher is


-

can forward call

Roadmap


Understanding context


Given an understanding of context, how can
applications use it?


Example applications


Two Approaches: Dey and Abowd, Dourish


Case Study and Discussion

What’s the Context?

Context:

What’s the Context

Context:

Shop in Indonesia

Video


http://www.youtube.com/watch?v=MTh5nC
N_3K0

Thoughts


Question: How do we
effectively infer

characteristics of situations and
usefully

supplement them with technology?

Goal [Dey and Abowd, 2000]


Apps like Active Badges using specific user
context

(e.g. location) as application input


Need representation of context


Helps to build context
-
aware applications


better embedded in the UbiComp and mobile realms


What is Context?


By example


Location, time, identities of nearby users …


By synonym


Situation, environment, circumstance


By dictionary [WordNet]


the set of facts or circumstances that surround a
situation or event


Problems:


New situations don’t fit examples


How to use in practice?


Operational Definition of Context

“Context is any information that can be used
to characterize the situation of an entity. An
entity is a person, place, or object that is
considered relevant to the interaction
between a user and an application,
including the user and the application
themselves.” [Dey and Abowd, 2000]

Observations

-
From point of view of developer


Active Badges


Application: help operator

forward calls to
researcher at appropriate location


Entity

Characteristic Info (context)

Researcher

Badge ID/Name, location,
?
Time of the workday
(morning, lunch, dinner)?


Room

Presence of a phone

Museum Audio Guide Example


Application: digital museum guide


Entity

Characteristic Info (context)

Museum
Patron (user)

Museum Audio Guide Example


Application: digital museum guide


Entity

Characteristic Info (context)

Museum
Patron (user)


Education, age, spoken
language, location in museum,
previously viewed artifacts

Exhibit

What area of museum

Mobile
Interface

battery life

Context Categories


Recall Dey’s goal: operational definition for use by
designers and developers


Once you have entities, want to identify frequently
useful contexts


Primary Categories


Answer basic questions like who, what, when, where


Index into more detailed secondary categories


Secondary Categories


More specific details that may be relevant

Primary Categories


Identity
: every entity has a unique id


Location
: position, spatial relationships
(latitude/longitude, with friends, near a
Starbucks, in the library)


Activity
: what’s happening in the situation
(touring a museum, reading a book)


Time
: current time, duration of event,
temporal ordering

Secondary Categories


Indexed by primary category


Phone number, address, social network,
etc..


E.g. identity
-
> email address, phone
number, etc..

Context
-
Aware Applications


“A system is context
-
aware if it uses context
to provide relevant information and/or
services to the user, where relevancy
depends on the user’s task.”


Context
-
Aware Features

1.
Presentation of information and services


Tour guide, Active Badges

2.
Automatic execution of services


Smart homes (turn off lights, adjust
temperature)

3.
Tagging of context to information for later
retrieval


Digital camera meta
-
data (time, location)

Context Toolkit [Salber et al, 1999]

Active Badges

Discussion


If you were designing an application and
you wanted to take advantage of context,
would this framework be helpful?


Example: cell
-
phone restaurant locator


Entities: ?


Relevant Characteristics (context): ?


Does this help the designer and user?

Dourish’s View on Context


What we talk about when we talk about
context [2004]


Consider a central goal of UbiComp


invisibility

of useful technology


Does not arise from design, but from
use

and
incorporation into practices

[Tolmie et al. 2002]

Dourish’s Context


Context is not


Set of stable features that characterize events


Representable


Context is


Emergent property of interactions (with people,
objects)




Dourish’s Context


Previous approaches to context are
representational
: “what is context and
how can it be encoded?”


Alternative approach uses
interactional

model: “how and why, in the course of their
interactions, do people achieve and
maintain a mutual understanding of the
context for their actions”

Implications of Representable
Context


Context is:


Form of information that can be encoded


Delineable: in advance define what contexts are
relevant for the application


Stable: determination of relevance of potential
context in an activity can be made once,
reused


Separable from activity

Context can be encoded



Alternative:


You cannot bundle up all the context


Objects can be
contextually relevant

-

Dey
: relevant info about entities
(people, exhibit, interface, …) is
context

-

Dourish
: all those things might
be contextually relevant, but they
do not fully describe the context

Context is Delineable


Alternative:


Scope of application’s contextual features is
defined dynamically

-

Dey
: When contexts X, Y, Z
come into play, feature A can be
engaged

-

Dourish
: problematic

Context is Stable


Alternative


Context is an occasioned property


Particulars of situation and activity matter


-

Dey
: Relevance of user’s
proximity to an exhibit is always
relevant

-

Dourish
: highly dependent on
the current situation

Context is separable from Activity


Alternative


Context is produced,
maintained and enacted
while doing the activity


Dey sort of agrees, but
for him activity is very
general

Practice


Practice: find meaning in the world by
seeing what actions we can engage in


Computer scientist example


Context concerns:


How actions become meaningful in certain
situations


Practice


Practice evolves => Context Evolves


Implications on Design


Technology becomes meaningful as
individuals engage with it


Use may not align with designer’s
conception:


Unexpected uses (e.g. SMS)


Generally used features “particularized”
differently (e.g. our different uses of folder
hierarchies)

Implications on Design


Predefined contexts will likely fail


“How can ubiquitous computing support the
process by which context is continually
manifest, defined, negotiated, and shared?”


Support evolution of meaning through
practice

Example Application


Structures in Information Spaces


User places items in a two dimensional
space, interact directly with data


System suggests relationships, user may
work off those suggestions

Suggested by
Application

Discussion


Building an application


Current applications

Building an Application


If you were designing an application and
you wanted to take advantage of context,
would these frameworks help?


Example: cell
-
phone restaurant locator


Do these help the designer and user?

Dey

Entities: ?

Relevant Characteristics
(context): ?

Context
-
Aware App?


Dourish

Context Engaging/Producing
App?


Both?


Case Study: Web Apps


Do they match up with our discussion of context?


How effective are they?


What are the problems?


What can they learn from the views of context
discussed here?


Dey
: Context can be represented and processed


Dourish
: Context is emergent. Applications
should help users produce new meanings and
contexts

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