I would just use a simple forking tcp server to accept connections, do stuff, and return the values, but I may be slightly biased in their favor as I just did a bunch of stuff using them. Anyways, the code would look something like:

$SIG{CHLD}='IGNORE'; # no zombies for me!

use IO::Socket;
my $server = new IO::Socket::INET
(
    LocalPort=>2000,
    LocalAddr=>'127.0.0.1',
    Type=>SOCK_STREAM,
    Reuse=>1,
    Listen=>10,
);

while(my $client = $server->accept)
{
    my $pid = fork;
    next if $pid;
    #
    # This is the body of the forked child,
    # simply read from the client using <$client>
    # and write using print $client foo;
    # then exit the child (DO NOT FORGET);
    exit;
}
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Then you could simply use IO::Socket::INET to create a socket that connects to the above server and reads/writes commands to it.