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Glossary of LocoMedia Terms - in progress

Context
Context Driver
CyberJacket
Device Driver
Device Manager
Domain
Domain Server
FootBridge
FootBridge Manager
GPS
Handshake
InfoPost
Integrated Networks
LocoMedia
Note
Pinger
Policy
Policy Manager
Service
Socket

 

Context

The LocoMedia system allows notes to be tagged with contextual information expressed in terms of references to domains and optional numeric values. A reference to a domain appears like a file pathname (e.g. /location/name/UK/Bristol). Here are some examples of contextual information:

The context of a note is the set of all domains which the note was published with (including any default domains, like user name) and their values (if any).

The current context is the set of all current environment inputs (coming from context drivers like GPS) plus the set of domains which the user is subscribed to.

Context Driver

A specialised device driver that provides only services that relate to the current context of the user.

CyberJacket

Our wearable computer. This is the hardware on which the LocoMedia system is to run. Currently it comprises an Epson 486 PC card running Linux software, with a PC104-based motherboard, audio input and output and GPS location sensing. By the end of Summer 98 it will also have differential GPS, a pinger receiver, a Footbridge transceiver and a cellular phone. The hardware is stitched into the lining of a jacket.

Device Driver

A program that runs on the CyberJacket and provides services to other device drivers or processes. Device drivers may provide the interface between physical devices and processes on the CyberJacket, or they may transform data from one or more sources to give more data that is hopefully of more use.

Device Manager

The device manager is responsible for informing devices on the system as to what services are currently available for use by other devices, and where these services can be found. It works by allowing devices to self register services they offer, and to specify the name of the socket where the data can be obtained from.

Domain

Domains are used to represent real world objects and concepts. They may represent the author of a note, the topic of a note, the name of the place where the note was recorded or anything else. In some cases it is convenient to describe things using numbers, and in this case the domain is used to define what the number means. The number itself is stored as part of the Context of a note. As an example, a number may be used to represent the visibility in yards. In this case, Visibility would be the domain and the note context would contain the value.

Domains provide a common way of representing context information. They are maintained in public directories. Any user can define a new domain and place it in the domain hierarchy. The CyberJacket manages domain references as abstract data types - it has no understanding of the meaning of any individual domain reference.

Domain Server

The domain server is used to publicise the existence and meaning of domains. It allows anyone to register new domains and define what they mean. In addition, it supports domain name aliases. This allows different users to refer to the same interest (or location etc.) by different names.

FootBridge

FootBridge Manager

GPS

The Global Positioning System utilises the $13 billion constellation of satellites in sunsynchronous orbit above the earth, developed by the US department of defence. Access is free to all users and provides accurate location and timing information.

Equipped with atomic clocks the 24 satellites orbit 12,000 miles above the earth, constantly transmitting the precise time and their position in space. GPS receivers listen to these signals and use the information to determine the location of the receiver as well as how fast and in what direction the receiver is travelling.

Handshake

LocoMedia

Note

A note is the essential information element in our Cyberjacket. A note has two parts: content and context. The content can be pretty much any type of media: audio, text, images, whatever. The context describes anything you like about the note. It might be simple things like the time when it was created, the name of the author or the place where it was recorded. The context might refer to the topic of the note like a painting in a gallery that you are visiting. The context could even be used to describe the conditions under which the associated note is to be rendered, perhaps only if you are near a certain place and the weather is good (in which case the note will tell you that you will have a magnificent view from the top of Cabot's tower), or only Saturday's at 5pm (when the cookie shop is closing for the weekend and selling their cookies at half price).

Pinger

A Pinger is a localised radio transmitter capable of transmitting over an area of not more than 2-3 metres. Pingers transmit an individual and predetermined number at regular intervals (ideally every 1 second). It is planned that a large number of pingers would be placed around a building at convenient points. The Cyberjacket would be able to receive these signals and be able to determine the users position. Pingers form the indoor component of True GPS.

Policy

Policy is the means by which a user can instruct their CyberJacket how to handle notes in various circumstances. There is to be a policy language that allows users to associate opportunities (e.g. new notes are available for download), a type of note (e.g. /commercial/adverts) and a decision (yes, no or ask the user each time).

Policy Manager

Service

Something that will create,modify or process data in some way, and can be advertised for use by processes by registering with the device manager.

Socket

Allows data to be passed between different concurrent processes. Appears as a special file entry in the UNIX file system to allow processes to open it for read and write operations.


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