networks & systems laboratory> research> current projects> dcaf - a distributed context aware framework

dCAF - A Distributed Context Aware Framework
Smart Internet Technology Research Group

Aims & Motivation

- To develop a distributed context aware framework.

- Enable different applications to respond to different sensors in a unified way.

- Efficiently updating context in diverse and dynamic environments.

- Context information is essential to the creation of intelligent and effective ubiquitous computing environments.

- This information should be available anywhere and anytime the applications can run.

- Effective routing and filtering of this information must be utilised to control the flow of context information.

Technical Discussion

Distributed Context

- Applications need to be able to deal with the case where a user may spend time in more than one organisational unit. For example, a user may use the same application both at work and at home.

- dCAF allows local Context Servers to be run at each local organisation unit; a global distributed hash system keeps track of organisational name to server location mappings.

- By running a local server at each site network traffic related to that area is isolated the local area network.


dCAF
- dCAF applications are built upon a C++ framework. Communication to the local context servers uses the Spread Toolkit, local Context Servers are discovered by searching in a peer to peer distributed hash table.
- Applications are able to subscribe to particular rooms or areas of interest, and can broadcast details of events that happen within those rooms.

Application Overview
- The Context Server is responsible for maintaining the structure of the network.
- Each room in the system is defined in a hierarchical nature. The Context Server passes messages up the tree to allow subscriptions to larger areas. For example, a message in “G62” will also been seen in “Madsen”, and “USYD”.
- Messages about mobile users (e.g. Fred) can also be subscribed to from the Context Server. Whenever Fred enters or leaves a room a message is sent to all application that have subscribed.
- Applications can also send query messages to user channels, where applications can reply with information. For example, a meeting organiser could send a message to Fred to find his availability over the upcoming week, and to request an available time to meet.

 

Example Applications

Follow Me Music:
- The goal of this application is to play the users configured music play list at the speakers that are closest to that user, and to turn the music off when he/she leaves the room. Another application could be to lower the volume when another person enters the room, or to combine the play list of both parties.
Intelligent Printing:
- By combing the information about the location of the user and nearby printers, an intelligent print queue is able to select the printer that is closest to the user, and has the fewest queued jobs.
Follow Me Phone:
- By registering a phone number with a Voice over IP gateway, the application is able to re-route telephone calls to the users last known position, it is also able to filter calls when the user is unavailable to take the call.
Intelligent Communication:
- The goal of this application is to work out what is the best way to communicate with a given individual. For example, it may be faster to call the person at his/her desk, send an email, an SMS, or maybe call their mobile.

Example of the System in Use
- The application below shows a plan view of the Madsen building, this plan is generated by querying the Context Server associated with the Madsen building.
- Each room flashes whenever a message is sent involving an entity entering or leaving that room.
- The user of the application can send a message to a selected room by way of a Voice over IP gateway.

Future Work
- Develop a model for secure and authenticated messaging system.
- Provide a framework and documentation so that others can easily set up and install a system and integrate existing applications.
- Install and configure a larger collection of Context Sensor applications.

Contacts
- Mark Assad
- Bob Kummerfeld

 
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