Architecture for Context-Aware Services in Gaia

Anand Ranganathan

Why context?

Situational information, or context, increases richness of communication in human-computer interaction

Makes it possible to produce more useful computational services

Challenges in using context

To develop a taxonomy and uniform representation of context types

Infrastructure to promote design , implementation and evolution of context-aware applications

Discovery of compelling context-aware applications

Issues of privacy and security

Different types of context

Physical – Location, TimeEnvironmental – Weather, stock quotes,

sports scoresSocial – Activity, Individual & Group

dynamics, MoodsApplication – email, websites visitedSystem – network traffic, status of

printers

Context-Aware Apps

Context-Aware PlannerContext-Aware Ambience Generator

Context-Aware Planner

Gives suggestions for an individual can plan out his activities

Uses context like:LocationTimeWeatherMovie listingsConcert/Symphony timingsHistory of what he/she has done

Context-Aware Planner- 2

Group activities can be plannedUsing social context between two or

more people – like similar interests, relationship, etc.

Context-Aware Ambience Generator

Context-Aware Ambience Generator

Based on moods of persons in room, social contexts, festivals, whether there’s a football game going on, etc. suitably changing the ambience of a room

Music, lighting, TV/radio

Specifying context

Apps must be able to specify what type of context they want and in what format.

Context sensors must be able to send context to the apps.

Format should be flexible and extensibleStandardised?

XML for specifying context

Apps to specify context they requireContext TypeApp ID (UCR/IOR)Real Time / HistoryEvent based / PollingTime to liveFormatBoolean expression (for notifications )Granularity / Reliability

XML for specifying context –2

Context sensors send apps their contextContext TypeTimestampSourceID (UCR)Value of context

What do context-aware apps want?

Contextual information in a format they can understand (eg in temp in C or F)

Want to be notified when a context they are interested in occurs (eg. When temp > 98 F)

Want to be able to poll or query certain types of context (eg. What is temp now?)

Want to access context history (how did temp change ?)

Don’t care about actual context sensor

Infrastructure

Context Engine

Context Widget Context Widget Context Widget

Context Provider Context Provider

Context Synthesizer

Context History

App App App

Context Widget

Actually senses the contextEg. The Ibutton reader, RF badge

basestationGets address of context provider(s) and

sends it events

Context Provider

Stores subscriptions of context consumers and sends them events

Apps can also query themCan do some interpretation / translation

of context from one form to another

Context Engine

Similar to Trader ServiceContext providers “advertise” the

context they provide, the granularity, real-time/history, etc. with CE

Context consumers query CE for appropriate context.

Context Synthesizers

Makes use of more than one context to give another contextual cue.

Eg. Deducing if a meeting is taking place based on no. of people, sound, whether there’s a powerpoint ppt.

Is a context consumer and context provider

Context History

Databases that subscribe to contextual information

Keep recording specific contexts like the location of a person

Is also a context consumer + context producer

More details

ContextProvider interface GetContext(XMLFile)GetContext(XMLFile, IOR)

ContextConsumer interfaceSendContext(XMLFile)

Future issues

Resolving ambiguous contextWhere does privacy fit in?