The Gaia System

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The Gaia System
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Not Invented Here

• Lots of Pervasive Computing Projects
• Carnegie Mellon Univ.
• U. Washington
• Georgia Tech
• UC Berkeley
• Univ. Illinois Urbana Champaign
• Gaia
• England Scandinavia ??

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Similarities

• Pervasive computing can be characterized as
• Extensive management for components (services,
  devices)
• Components are autonomous
• Some application programming support
• Java or Python
• Rules or scripts
• Still very primitive (in my opinion)

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Gaia Architecture
Applications
QoS Adaptation Service
Application Framework
QoS Instantiation Service
Configuration Management Service
Context File System
Context Service
Component Repository
Presence Service
Space Repository
Component Management Core
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Component Management Core

• Provides functionality to manipulate components
  in Gaia
• Creation
• Destruction
• Uploading
• Contains three basic abstractions
• Components
• Component Containers
• Nodes

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Component Management Core
Active Space
Gaia Component Container
Gaia Node
Gaia Node
Gaia Components
Gaia Component Container
Gaia Node Examples
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Gaia Kernel Services

• Event Manager
• Context Service
• Context File System
• Component Repository
• Presence Service
• Space Repository

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Event Manager

• Loosely coupled communication based on channels.
• Supports push, pull, and hybrid mechanisms.
• Supports creation of named event channels and
  distribution of load.

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Event Manager
Event Channel Factory 1
Event Channel Factory n
Suppliers
Suppliers
. . .
Event Manager
Event Channels
CreateChannelType DeleteChannelType CreateEventCha
nnel GetEventChannel DeleteEventChannel ListChanne
lTypes ListEventChannels
Consumers
Consumers
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Context-Aware Applications

• Situational information, or context, increases
  richness of communication in human-computer
  interaction.
• Makes it possible to produce more useful
  computational services.
• Example contexts location, time, weather, stock
  prices, moods, user activity,

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Context Service

• Provides a taxonomy and uniform representation of
  context types.
• Provides an infrastructure to promote design,
  implementation, and evolution of context-aware
  applications.

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Context File System

• Data Organization
• Context affects data organization.
• Data important in current context is easily
  accessible.
• Can attach context to files and directories.
• Context situation, location, space, group, time.
• Data Transformation
• Applications open data as desired type
  dynamically typed file system.
• System converts data to desired type.

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Data Organization
space office location RM2401 time 11/28/01
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Data Transformation
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Component Repository

• Provides persistent storage of components.
• Allows addition, removal, and browsing of
  components.
• Used by Component Management Core to dynamically
  retrieve components.

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Presence Service

• Detects the presence of digital and physical
  entities.
• Generates events based on entity presence
• ENTER
• LEAVE
• Defines a group of event channels to disseminate
  presence information.
• Maintains soft-state of all digital entities
  through a leasing mechanism.

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Presence Service
Physical Entity Presence
Person Presence Channel
Person
Application Presence Channel
Person Tracker
Enter Leave Events
Device Presence Channel
Service
Service Presence Channel
Digital Entity Presence
Application
Device
Event Manager Channels
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Space Repository

• Centralized repository containing information
  about active entities.
• Interacts with Presence Service to keep
  information up to date.
• All entities described by a set of properties
  (e.g., entity type, name, location, owner).
• Exports a query interface based on properties.

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Space Repository
Presence Channels
Component
Detection Mechanism
Component
Query Interface
Database
Component
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Application Framework

• Active Spaces render traditional applications
  obsolete.
• Applications for Active Spaces are
• Distributed
• Adaptable
• Mobile
• Multi-Machine User Interface

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Traditional Application Mapping
Application Logic
Display
Controller
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Active Space Application Mapping
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Model Presentation Controller Coordinator
Application Framework
Model
Controllers
Presentations
Slide Show Data
Application Functional Level
Application Meta-Level
Coordinator
MPCC Application
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MPCC Application Framework

• Model encapsulates the application logic.
• Presentation presents the data of the model
  (audio, video, changes in the physical
  environment).
• Controller modifies the state of the model.
• Coordinator manages the application
  architecture (application meta-level).

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Application Generic Description
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Application Concrete Descp.
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Applications

• Mobile Video
• Context Data Browser
• Presentation Viewer

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Mobile Video
Move!
Location A
Location B
Media Gateway
Media Server
Component Database
User Profile Server
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Context Data Browser
Context Mode
File Mode
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Presentation Viewer
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The Context Model

• Enables creation of complex, first-order
  expressions involving context
• Makes it possible to write rules, prove theorems,
  evaluate queries

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Basic Structure

• Four parts
• context-type
• Subject Person, place, or thing
• Relater something that related subject to object
• Object is a value associated with subject

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Some examples

• Context(Location, Chris, Entering, G868)
• Context(Temperature, G868, Is, 98F)
• Context(Stock Quote, IBM, gt, 60 )
• Context(Printer Status, Pulp, Is, Empty)
• Context(Time, New York, Is 1200 01/01/04)

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Operations on Contexts

• Boolean, Existential, Quantification
• Context(lighting, G868,Is,Off) OR
• Context(lighting, G828,IS, Dim)

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Context Chat