The Gaia System Not Invented Here

The Gaia System

Not Invented Here

• Lots of Pervasive Computing Projects

• Carnegie Mellon Univ.
• U. Washington
• Georgia Tech
• UC Berkeley
• Univ. Illinois Urbana Champaign
• Gaia
• England & Scandinavia & ??

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)

Gaia Architecture

Component Management Core

• Provides functionality to manipulate components in Gaia:

• Creation
• Destruction
• Uploading

• Contains three basic abstractions:

• Components
• Component Containers
• Nodes

Component Management Core

Gaia Kernel Services

• Event Manager

• Context Service

• Context File System

• Component Repository

• Presence Service

• Space Repository

Event Manager

• Loosely coupled communication based on channels.

• Supports push, pull, and hybrid mechanisms.

• Supports creation of named event channels and distribution of load.

Event Manager

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, …

Context Service

• Provides a taxonomy and uniform representation of context types.

• Provides an infrastructure to promote design, implementation, and evolution of context-aware applications.

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.

Data Organization

Data Transformation

Component Repository

• Provides persistent storage of components.

• Allows addition, removal, and browsing of components.

• Used by Component Management Core to dynamically retrieve components.

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.

Presence Service

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.

Space Repository

Application Framework

• Active Spaces render traditional applications obsolete.

• Applications for Active Spaces are:

• Distributed
• Adaptable
• Mobile
• Multi-Machine User Interface

Traditional Application Mapping

Model – Presentation – Controller – Coordinator Application Framework

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).

Application Generic Description

Application Concrete Descp.

Applications

• Mobile Video

• Context Data Browser

• Presentation Viewer

Context Data Browser

Presentation Viewer

The Context Model

• Enables creation of complex, first-order expressions involving context

• Makes it possible to write rules, prove theorems, evaluate queries

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

Some examples

• Context(Location, Chris, Entering, G868)

• Context(Temperature, G868, Is, 98F)

• Context(Stock Quote, IBM, >, $60 )

• Context(Printer Status, Pulp, Is, Empty)

• Context(Time, New York, Is 12:00 01/01/04)

Operations on Contexts

• Boolean, Existential, Quantification

• Context(lighting, G868,Is,Off) OR

• Context(lighting, G828,IS, Dim)

Context Chat