Using liveCaster to multicast textual attributes

(For instructions on how to multicast MPEG audio data, see here) When running in 'attribute' mode, liveCaster uses a multicast channel to 'announce' the contents of a file system directory (i.e., folder). This directory should contain one or more text files (with suffix ".txt"), each describing a data record to be announced over the multicast channel. These data records each consist of a set of textual attributes: (name,value) pairs.

Example 1: Announcing stock prices

In this example, a directory - named "stocks" - contains two files "ACME.txt" and "RNDM.txt", each describing the stock price of a (hypothetical) company.

Contents of the file "ACME.txt":

info    ACME Enterprises, Inc.
high	13.25
low     12.875
last	13.125
time	1/30/1998 3:59pm

Contents of the file "RNDM.txt":

info    Random Software Corporation
high	37.5
low     11.25
last	ll.25
time	1/30/1998 3:55pm

Example 2: Announcing weather data

In this example, a directory - named "weather" - contains a file "SFO.txt" describing the current weather conditions in San Francisco.

Contents of the file "SFO.txt":

nickname San Francisco
{current conditions} partly cloudy
tempF 58


You may create and modify these ".txt" files using any method of your choosing. You could, for example, simply use a text editor. Alternatively, you could use a separate program - perhaps connected to a sensor or other data feed - to update these files. liveCaster will automatically notice when a file has been modified; it will then start announcing the new attribute value(s). liveCaster will also notice when new ".txt" files are added, and/or previously existing ".txt" files are deleted.

At present, liveCaster is intended for multicasting small pieces of textual information - not large files. liveCaster will exit with an error message if it sees a ".txt" file that's larger than a predetermined limit (currently, 2000 bytes).

Specifying a directory to announce

Upon starting liveCaster, you will see a dialog that you can use to navigate to the directory that you wish to announce. Once you're inside this directory, click the "Choose the current directory" button. (If the directory that you wish to announce does not yet exist, you can create it - as a subdirectory of the current directory - by clicking the "Create New" button.)

Alternatively, you can specify the directory to announce by starting liveCaster with the -d <directory path> command line option. (<directory path> must be a directory that already exists.) This option is useful if you wish to launch liveCaster automatically from a script.

Specifying the directory parameters

If the directory is being announced for the first time, you will then be presented with a second dialog ("Enter directory parameters"), which will give you the opportunity to set (or change) the network parameters for the announcement. This dialog is preset with default values. If you're happy with these values, click "OK" (or type the <Enter> or <Return> key). The parameters are described below: liveCaster stores these parameters in the directory's "SELF.txt" file.

When liveCaster is running

In normal operation (after a directory has been selected and its parameters set up) liveCaster will display a small window, indicating the directory that is currently being announced.

This window may be minimized (and liveCaster will continue running in the background). To exit liveCaster, delete this window, or type <Control>-q.

Running liveCaster without a GUI

Receiving and viewing liveCaster's attribute announcements

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