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Simple talker written in Perl
Interprocess Communication example from a Well House Consultants training course
More on Interprocess Communication [link]
Source code: talker Module: P223
#!/usr/bin/env perl
# Program: talker # Purpose: Provide a "talk" service # Copyright: Well House Consultants, +44 (0) 1225 708225 # web: http://www.wellho.net use Socket; # Set up listener $on_port = ($ARGV[0] || 7777) ; $proto = getprotobyname("tcp"); socket (Server, PF_INET, SOCK_STREAM, $proto) || die ("socket "); setsockopt(Server, SOL_SOCKET,SO_REUSEADDR,1); $pbind = sockaddr_in($on_port,INADDR_ANY); bind(Server,$pbind); listen(Server,SOMAXCONN); $switchboard = $$; messanger() unless ($pid == fork) ; # await a contact while ($paddr = accept(Client, Server)) { ($port,$iaddr) = sockaddr_in($paddr); @host_ip = unpack('C4',$iaddr); $host_name = gethostbyaddr($iaddr,AF_INET); # print "ON @host_ip $host_name ",`date`; # Fork handling process unless ($pid == fork) { $SIG{"USR2"} = "send_to_client"; open (HELLO,">>/var/talker/$on_port.0"); print HELLO $$," $host_name on\n"; close HELLO; kill 'USR1',$switchboard; sleep 1; select Client; $|=1; print Client "Link Established! .q to quit, .w for who\r\n"; while ($from_client = <Client>){ open (MESSAGE,">>/var/talker/$on_port.1"); print MESSAGE "$host_name",": $from_client"; close MESSAGE; kill 'USR2',$switchboard; last if ($from_client =~ /^\.q/); } $|=0; select STDOUT; open (HELLO,">>/var/talker/$on_port.0"); print HELLO $$," $host_name off\n"; close HELLO; kill 'USR1',$switchboard; # print "OFF @host_ip $host_name ",`date`; unlink "/var/talker/$on_port.$$"; exit; } close Client; } ##################################################### sub messanger { # start a messangering process unlink "/var/talker/$on_port.0"; unlink "/var/talker/$on_port.1"; $SIG{"USR1"} = "new_client"; $SIG{"USR2"} = "client_message"; while (1) { sleep 20; } } ##################################################### sub new_client { open (NEW,"/var/talker/$on_port.0"); $clients = <NEW>; ($process,$host,$direction)=split(/\s+/,$clients); close NEW; unlink "/var/talker/$on_port.0"; if ($direction eq "off") { delete $connection{"$process"}; broadcast ("*** $host has gone offline ***"); } else { $connection{"$process"} = $host; broadcast ("*** $host has come online ***"); } } ######################################################## sub client_message { open (MSG,"/var/talker/$on_port.1"); $message = <MSG>; close MSG; unlink "/var/talker/$on_port.1"; chomp $message; @look = split(/\s+/,$message); if ($look[1] =~ /^\.w/) { @vconn = values (%connection); $look[0] =~ s/:$//; $message = "$look[0] enquires who: @vconn"; } if ($look[1] =~ /^\.b/) { $message .= "\a"; } broadcast ($message); } ######################################################## sub broadcast { my ($message) = @_; chop ($date = `date`); open (LOG,">>/var/talker/$on_port.2"); print LOG $date," ",$message,"\n"; close LOG; # send to EACH client for general release! $bleep = ((time()-$recent) > 600)?"\a":""; foreach $process(keys %connection) { open (MSGOUT,">/var/talker/$on_port.$process"); print MSGOUT "$bleep$message$bleep\r\n"; close MSGOUT; kill "USR2",$process; } $recent = time(); } ############################################################ sub send_to_client { open (MSOUT,"/var/talker/$on_port.$$"); $mout = <MSOUT>; close MSOUT; print Client "$mout"; } Learn about this subject
This module and example are covered on our public Perl Extra course. If you have a group of
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Other Examples
This example comes from our "Interprocess Communication" training module. You'll find a description of the topic and some
other closely related examples on the "Interprocess Communication" module index page.
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