NAME IPC::MorseSignals - Communicate between processes with Morse signals. VERSION Version 0.07 SYNOPSIS use IPC::MorseSignals qw/msend mrecv/; my $pid = fork; if (!defined $pid) { die "fork() failed: $!"; } elsif ($pid == 0) { my $s = mrecv local %SIG, cb => sub { print STDERR "received $_[1] from $_[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, sign => $sign ] 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. Default speed is 512, don't set it too low or the target will miss bits and the whole message will be crippled. If the "utf8" flag is set (default is unset), the string will first be encoded in UTF-8. The "utf8" bit of the packet message is turned on, so that the receiver is aware of it. If the "sign" flag is unset (default is set), the PID of the sender won't be shipped with the packet. "mrecv" mrecv %SIG [, cb => $callback ] Takes as its first argument the %SIG hash and returns a hash reference that represent the current state of the receiver. %SIG's fields 'USR1' and 'USR2' will be replaced by the receiver's callbacks. "cb" specifies the callback to trigger each time a complete message has arrived. Basically, you want to use it like this : my $rcv = mrecv local %SIG, cb => sub { ... }; In the callback, $_[0] is the sender's PID (or 0 if the sender wanted to stay anonymous) and $_[1] is the message received. "mreset" mreset $rcv Resets the state of the receiver $rcv. Useful to abort transfers. "mbusy" mbusy $rcv Returns true if the receiver $rcv is currently busy with incoming data, or false otherwise. "mlastsender" mlastsender $rcv Holds the PID of the last process that sent data to the receiver $rcv, 0 if that process was anonymous, or "undef" if no message has arrived yet. It isn't cleared by "mreset". "mlastmsg" mlastmsg $rcv Holds the last message received by $rcv, or "undef" if no message has arrived yet. It isn't cleared by "mreset". EXPORT This module exports any of its functions only on request. 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 header is composed by the "utf8" bit (if the data has to be decoded to UTF-8), the "sign" bit (if sender gives its PID in the header), and then 24 bits representing the sender's PID (with highest weight coming first) if the "sign" bit is set. The emitter computes then the longuest sequence of successives 0 (say, m) and 1 (n) in the concatenation of the header and the data. 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 header, the data bits and the reversed signature (i.e. the bits of the signature in the reverse order). a ... a b | u s [ p23 ... p0 ] | ... data ... | b a ... a signature | header | data | reversed signature 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, "" 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 . 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.