sawanv has asked for the wisdom of the Perl Monks concerning the following question:

Hello All. Can anyone give me a few pointers for writing a daemon in Perl? Something that listens on some port and replies to some requests made via sockets. What stuff do I need to know (functions, libraries, modules, packages etc)? Hints, tips, URLs, welcome. Thanks Sawan

Replies are listed 'Best First'.
Re: Daemons in Perl
by IlyaM (Parson) on Jan 15, 2003 at 09:13 UTC
[reply]
Re: Daemons in Perl
by dws (Chancellor) on Jan 15, 2003 at 09:16 UTC
    Can anyone give me a few pointers for writing a daemon in Perl? Something that listens on some port and replies to some requests made via sockets. What stuff do I need to know (functions, libraries, modules, packages etc)?

    Linconl Stein's Network Programming with Perl covers everything you need to know.

    A careful study of HTTP::Daemon will also be rewarding.

    Try a Super Search for "Daemon".

[reply]
Re: Daemons in Perl
by herveus (Prior) on Jan 15, 2003 at 12:19 UTC
    Howdy!

    Net::Server also provides a flexible framework for writing servers. I found it to be straightforward to use.

    Now, you say you are looking for a daemon, but then describe a server. The two are not exactly the same thing in my mind. A daemon does not necessarily listen on ports; it may be doing other tasks (useful or useless, as it may be) that are strictly local to the machine. A server listening on a port can be a special case of a daemon.

    yours,
    Michael

[reply]
Re: Daemons in Perl
by castaway (Parson) on Jan 15, 2003 at 09:42 UTC 
    $sockserv = new IO::Socket::INET( LocalAddr => '192.168.1.1',
                              LocalPort => $port,
                              Proto     => 'tcp',
                              Listen    => 1,
                              Reuse     => 1,
                              Timeout   => 60);
die "can't start server: ($!)\n" unless $sockserv;

$x = IO::Select->new();
$x->add($sockserv);
while(1)
{
   @handles = $x->can_read();
   foreach $handle (@handles)
   {
       if($handle == $sockserv)
       {
            $sockclient = $sockserv->accept() || warn "accept: $!";
            $clients++;
            if ($clients > 5)
            {
                print $sockclient "Sorry, we're full.\n";
                $sockclient->close();
            } else
            {
                $sockclients[$clients] = $sockclient;
            }
            $x->add($sockclients[$clients]);
        }
        ($cl) = grep($sockclients[$_] == $handle, (0..$#sockclients));
        if ($cl)
        {
            $n_read = sysread($sockclients[$cl], $buf, 1024);
            return 0 if (!n_read || !length $buf);
            parse_external_command($buf, $sockclients[$cl]);
        }
    }
}

    [download]
    something like that.. where parse_external_command() reads what the client said, and answers via the passed in socket if necessary.
    C.
[reply]
[d/l]
      Hmm, I'm missing a: 
      die "can't start server: ($!)\n" unless $blah;

      [download]
      in there.
      C.
[reply]
[d/l]
Re: Daemons in Perl
by mce (Curate) on Jan 15, 2003 at 13:42 UTC
    The cookbook chapter 17 should get you started.
    ---------------------------
    Dr. Mark Ceulemans
    Senior Consultant
    IT Masters, Belgium
[reply]
Re: Daemons in Perl
by defyance (Curate) on Jan 15, 2003 at 19:30 UTC
    You could also have a look at Proc::Deamon for some ideas. I've found it to be useful in the past.

    -- Can't never could do anything, so give me and inch, I'll make it a mile.

[reply]
Re: Daemons in Perl
by Marza (Vicar) on Jan 15, 2003 at 20:04 UTC

    There is Dave Roths Win32::Daemon I have not tried it myself, but I have been happy with his other stuff.

[reply]
      Hello all. Thanks for you help and postings all. Sorry for confusion over daemon and server..forgive a newbie. Will check out all your tips. Sawan
[reply]

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