You are looking at a very old, but free version of the course. If you are interesed the most recent version, check it out on the Perl Maven site.

9.4. Echo Server

The Echo Server lets you telnet to it and echos back every word you type just
like the Simple Echo Serever but once connected you have 5 seconds between 
every two line you type or it prints Timeout and closes the connection. 
Prints a message both to the client and the console (STDERR) of the server.

Example 9-5. examples/server/echo_server.pl

#!/usr/bin/perl
use strict;
use warnings;

use lib 'lib';
use EchoServer;

EchoServer->run(port => 8000);

Example 9-6. examples/server/lib/EchoServer.pm

package EchoServer;
use warnings;
use strict;

use base 'Net::Server';
use English qw( -no_match_vars ) ;

my $timeout = 5; # give the user 5 seconds to type a line
my $EOL   = "\r\n";

sub process_request {
    my $self = shift;
    eval {

        local $SIG{ALRM} = sub { die "Timeout\n" };

        alarm($timeout);
        while( my $line = <STDIN> ) {
            alarm($timeout);
            $line =~ s/\r?\n$//;
            print qq(You said "$line"$EOL);
            last if $line eq "bye";
        }
    };
    alarm(0);

    
    if ( $EVAL_ERROR ) {
        if ( $EVAL_ERROR eq "Timeout\n" ) {
            print "Timed Out. Disconnecting...$EOL";
            print STDERR "Client timed Out.\n";
        } else {
            print "Unknown internal error. Disconnecting...$EOL";
            print STDERR "Unknown internal error: $EVAL_ERROR\n";
        }
    } else {
        print STDERR "User said bye\n";
    }
    return;
}



1;

If you are interested in on-site trainings by the author, please contact me directly.