Page 242 - Asterisk™: The Future of Telephony

my $result = <STDIN>;
&checkresult($result);
The second part of this test plays back the audio that was recorded earlier, using the
STREAM FILE command. We’ve already covered STREAM FILE, so this section of code
needs no further explanation.
print STDERR "================== Complete ======================\n";
print STDERR "$tests tests completed, $pass passed, $fail failed\n";
print STDERR "==================================================\n";
At the end of the AGI script, a summary of the tests is printed to STDERR, which should
end up on the Asterisk console.
In summary, you should remember the following when writing AGI programs in Perl:

• Turn on strict language checking with the use strict command. §
• Turn off output buffering by setting $|=1.
• Data from Asterisk is received using a while(<STDIN>) loop.
• Write values with the print command.
• Use the print STDERR command to write debug information to the Asterisk console.

The Perl AGI Library

If you are interested in building your own AGI scripts in Perl, you may want to check
out the Asterisk::AGI Perl module written by James Golovich, which is located at http://
asterisk.gnuinter.net. The Asterisk::AGI module makes it even easier to write AGI
scripts in Perl.

Creating AGI Scripts in PHP

We promised we’d cover several languages, so let’s go ahead and see what an AGI script
in PHP looks like. The fundamentals of AGI programming still apply; only the pro-
gramming language has changed. In this example, we’ll write an AGI script to download
a weather report from the Internet and deliver the temperature, wind direction, and
wind speed back to the caller:

#!/usr/bin/php -q
<?php
The first line tells the system to use the PHP interpreter to run this script. The -q option
turns off HTML error messages. You should ensure that there aren’t any extra lines
between the first line and the opening PHP tag, as they’ll confuse Asterisk.
# change this to match the code of your particular city
# for a complete list of U.S. cities, go to

§ This advice probably applies to any Perl program you might write, especially if you’re new to Perl.

214 | Chapter 9: The Asterisk Gateway Interface (AGI)