Context and ContextAware Computing

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Context and Context-Aware Computing

• Omar Khan
• CS260, Fall 2006

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Background

• Ubiquitous computing in early 90s computing
  everywhere and invisible
• Implication
• Create applications that work seamlessly in human
  environments
• Understanding of context

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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
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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

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Whats the Context?

• Context

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Whats the Context
Context Shop in Indonesia
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Video

• http//www.youtube.com/watch?vMTh5nCN_3K0

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Thoughts

• Question How do we effectively infer
  characteristics of situations and usefully
  supplement them with technology?

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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

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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 dont fit examples
• How to use in practice?

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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

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Active Badges

• Application help operator forward calls to
  researcher at appropriate location

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Museum Audio Guide Example

• Application digital museum guide

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Museum Audio Guide Example

• Application digital museum guide

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Context Categories

• Recall Deys 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

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Primary Categories

• Identity every entity has a unique id
• Location position, spatial relationships
  (latitude/longitude, with friends, near a
  Starbucks, in the library)
• Activity whats happening in the situation
  (touring a museum, reading a book)
• Time current time, duration of event, temporal
  ordering

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Secondary Categories

• Indexed by primary category
• Phone number, address, social network, etc..
• E.g. identity -gt email address, phone number,
  etc..

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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 users
  task.

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Context-Aware Features

• Presentation of information and services
• Tour guide, Active Badges
• Automatic execution of services
• Smart homes (turn off lights, adjust temperature)
• Tagging of context to information for later
  retrieval
• Digital camera meta-data (time, location)

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Context Toolkit Salber et al, 1999
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Active Badges
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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?

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Dourishs 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

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Dourishs Context

• Context is not
• Set of stable features that characterize events
• Representable
• Context is
• Emergent property of interactions (with people,
  objects)

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Dourishs 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

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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

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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

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Context is Delineable

• Alternative
• Scope of applications contextual features is
  defined dynamically

• Dey When contexts X, Y, Z come into play,
  feature A can be engaged
• Dourish problematic

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Context is Stable

• Alternative
• Context is an occasioned property
• Particulars of situation and activity matter

• Dey Relevance of users proximity to an exhibit
  is always relevant
• Dourish highly dependent on the current
  situation

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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

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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 gt Context Evolves

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Implications on Design

• Technology becomes meaningful as individuals
  engage with it
• Use may not align with designers conception
• Unexpected uses (e.g. SMS)
• Generally used features particularized
  differently (e.g. our different uses of folder
  hierarchies)

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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

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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
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Discussion

• Building an application
• Current applications

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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?
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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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Gmail
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Yahoo! ZoneTag
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