NAME
    IPC::MorseSignals - Communicate between processes with Morse signals.

VERSION
    Version 0.05

SYNOPSIS
        use IPC::MorseSignals qw/msend mrecv/;

        my $pid = fork;
        if (!defined $pid) {
         die "fork() failed: $!";
        } elsif ($pid == 0) {
         local @SIG{qw/USR1 USR2/} = mrecv sub {
          print STDERR "received $_[0]!\n";
          exit
         };
         1 while 1;
        }
        msend "hello!\n" => $pid;
        waitpid $pid, 0;

DESCRIPTION
    This module implements a rare form of IPC by sending Morse-like signals
    through "SIGUSR1" and "SIGUSR2". Both of those signals are used, so you
    won't be able to keep them for something else when you use this module.

    But, seriously, use something else for your IPC. :)

FUNCTIONS
  "msend"
        msend $msg, $pid [, speed => $speed, utf8 => $utf8 ]

    Sends the string $msg to the process $pid (or to all the processes @$pid
    if $pid is an array ref) at $speed bits per second. If the "utf8" flag
    is set, the string will first be encoded in UTF-8. In this case, you
    must turn it on for "mrecv" as well. Default speed is 512, don't set it
    too low or the target will miss bits and the whole message will be
    crippled. The "utf8" flag is turned off by default.

  "mrecv"
        mrecv $callback [, utf => $utf8 ]

    Takes as its first argument the callback triggered when a complete
    message is received, and returns two code references that should replace
    "USR1" and "USR2" signal handlers. Basically, you want to use it like
    this :

        local @SIG{qw/USR1 USR2/} = mrecv sub { ... };

    Turn on the utf8 flag if you know that the incoming strings are expected
    to be in UTF-8. This flag is turned off by default.

EXPORT
    This module exports on request its two only functions, "msend" and
    "mrecv".

PROTOCOL
    Each byte of the data string is converted into its bits sequence, with
    bits of highest weight coming first. All those bits sequences are put
    into the same order as the characters occur in the string. The emitter
    computes then the longuest sequence of successives 0 (say, m) and 1 (n).
    A signature is then chosen :

    - If m > n, we take n+1 times 1 follewed by one 0 ;
    - Otherwise, we take m+1 times 0 follewed by one 1.

    The signal is then formed by concatenating the signature, the data bits
    and the reversed signature (i.e. the bits of the signature in the
    reverse order).

    The receiver knows that the signature has been sent when it has catched
    at least one 0 and one 1. The signal is completely transferred when it
    has received for the first time the whole reversed signature.

CAVEATS
    This type of IPC is highly unreliable. Send little data at slow speed if
    you want it to reach its goal.

    "SIGUSR{1,2}" seem to interrupt sleep, so it's not a good idea to
    transfer data to a sleeping process.

DEPENDENCIES
    Carp (standard since perl 5), POSIX (idem), Time::HiRes (since perl
    5.7.3) and utf8 (since perl 5.6) are required.

SEE ALSO
    perlipc for information about signals in perl.

    For truly useful IPC, search for shared memory, pipes and semaphores.

AUTHOR
    Vincent Pit, "<perl at profvince.com>"

    You can contact me by mail or on #perl @ FreeNode (Prof_Vince).

BUGS
    Please report any bugs or feature requests to "bug-ipc-morsesignals at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=IPC-MorseSignals>. I
    will be notified, and then you'll automatically be notified of progress
    on your bug as I make changes.

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc IPC::MorseSignals

ACKNOWLEDGEMENTS
    Thanks for the inspiration, mofino ! I hope this module will fill all
    your IPC needs. :)

COPYRIGHT & LICENSE
    Copyright 2007 Vincent Pit, all rights reserved.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.