If the socket is not connected, writing to it will return an error which you can then check. Usually, writing to a socket has a timeout which you cannot avoid due to the nature of TCP.

Personally, I would look at AnyEvent or one of the other frameworks to handle non-blocking sockets.

Maybe you can tell us what solutions you have looked at and where you have problems with them? If you want to roll your own solution, perlipc provides a good starting point IMO.

Could you please tell me how intercept the error coming from socket? Because I tried, the following:


...
OpenSocket();
sleep(5);
$str="Something to send";
$sock1->send($str);
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Then, during sleep I disconnect acting on server. When the application try to send the message, it exit from execution without print anything.

Maybe it would be a good idea to check the return value of ->send? The following program behaves as I expect, telling me that the remote end has closed the connection:

#!/usr/bin/perl
use IO::Socket;
my $sock1;

sub OpenSocket{
    $sock1 = IO::Socket::INET->new(
        PeerAddr => '192.168.1.99',
        PeerPort => 80,
        Proto    => 'tcp'
    );
    $sock1 or die "no socket :$!";
}

################ START SCRIPT #################

OpenSocket();
$str="Something to send";
while (1) {
    if( !$sock1->send($str)) {
        warn "Error: $! / $^E";
    };
}
close($sock1);
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I'm not sure if the autodie pragma also covers IO::Socket. If it does, maybe you want to use it, if not, you will have to check every function call you make yourself for success/failure.

What you link is an interesting start point, but I already checked these pages without find a solution to my issue!

In what way is IO::Select::can_write( [ TIMEOUT ] ); not a solution to your issue?

Ok, maybe I don't understand how the IO::Select works. :(
Could you please post an example on how I can implement it? Thank you!!

Adapting the SYNOPSIS gives me the following code:

    use IO::Select;

    $s = IO::Select->new();
...

    $s->add($some_handle);

    my $outbuffer;
    while( $running ) {
        if( length $outbuffer ) {
            my @writeable = $s->can_write($timeout);
            for my $client (@writeable) {
                print {$client} $outbuffer;
                # In reality, we'd need to maintain an outbuffer per c
+lient, but
                # that's not the point here
            };
            undef $outbuffer;
        } else {
            $outbuffer = refill_outbuffer;
        };
    };
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