Readings' list

In this paper he describes the different positions on the definiton of "context" and compares different conceptual models: widget model, infrastructure model and blackboard model.

Context

• Context in language: The text is not an encapsulated representation of an intended meaning, but rather is a cue that allows the anticipated audience to construct an appropriate meaning.
• Context in Human-Computer Dialog: in an interface we created a situation of communication,  therefore interpretation of intention depends on mutually available context.
• Context vs. Setting: something is context because of the way it is used in interpretation, not due to his inherent properties. The user of a computer system is always situated in some setting. Some aspect of the setting are used as a context.
  
  Context aware Computing: design of computing mechanism that can use characterization of some standard aspect of the user's setting as a context for interaction.

Models for context Awareness

A number of different organizing models have been proposed for coordinating multiple processes and components.

Widget (Dey et al.)

A widget is a device driver at a different level.

Networked Services (Hong and Landay 2001)

Client-server architecture. A client needs to find the location of the service and then set up a connection with it. A key feature is independence of components. Each service is handled by a process on some processor.

BlackBoard

Data centric rather than process centric point of view. A process posts messages to a common shared message board, and can subscribe to receive messages matching a specified pattern. Pattern matching may be of different type. All communications go through a centralized server.

Tradeoff criteria

• Efficiency
• Configurability: complexity in adding new or modifying components.
• Robustness: breakdown of components is common. The system must continue to function.
• Simplicity: easy for builder to understand so more people can use it.

Contrasts between models

Widget: tightly coupled and single manager control. Not robust and complex configuration.

Service model: less efficient, more configurable and robust

Blackboard: not efficient but easy to configure and robustness.

The interactive Workspace architecture

Two level of data:

    Event Heap: simple event tuple: short term
    Context Memory: XML database: long term

Research Direction

Coming up with the conceptual structure of what context is and how to represent the different aspect of it that matter to the application.