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Re^12: UDP connection

by BrowserUk (Pope)
on May 04, 2012 at 22:56 UTC ( #969002=note: print w/replies, xml ) Need Help??


in reply to Re^11: UDP connection
in thread UDP connection

my main goal was to show bidirectional communication was possible,

Bidirectional communication was never in question (by me).

My questions/concerns related to concurrent bidirectional comms (at the same endpoint), which AFAIK is impossible on any platform.

Of course, this never arises with the select loop mechanism, as there is only one thread of execution and it is either waiting; or processing a can_read state; or processing a can_write state; or an error state.

But with either a multi-threaded, or multi-process solution on multi-core hardware, it can be attempted -- as exampled by the idea that the client run one thread/process for doing the heartbeat and another for receiving the data -- and needs to be handled.

It can be handled (with threading at least), but unless the OP comes back and fills in a few of the blanks, there's probably little point in further pursuing the possibilities.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

Replies are listed 'Best First'.
Re^13: UDP connection
by falstad (Novice) on May 08, 2012 at 07:42 UTC

    I'm sorry for ignoring the node for so long. I took some days off from work for an exam -.- I've read the whole discussion and I'd like to thank you for your replies.

    As above mentioned the UDP packet size is never bigger than 65535 bytes, and the read won't last 10 secs either.

    While sending out the hexdump the server will notice the heartbeat and will send a response after it sent the data. The server will always respond to the heartbeat. Also we know for sure, that there is no hexdump which contains only one byte. They have several types and the smallest is around 20 bytes.

    The server can do with some delay in receiving the heartbeat. For testing it's fine to set up the timer to send heartbeat in every 9.9 secs.

    "The sending of the hexdumps is initiated by the server, when they become available; provided that is within 10 seconds of a heartbeat." It's possible that we start the server and there is no hexdump ready. So it is possible that we have to wait for several minutes for the first hexdump to come. The client continues to send the heartbeats regardless of it receives no data.

    I hope I've answered everything that wasn't clear.

      Try this:

      #! perl -slw use strict; use threads; use IO::Socket; $|++; use constant SERVER => '127.0.0.1'; use constant MAXIN => 65536; my $noBlock = 1; my @svrs = map{ IO::Socket::INET->new( Proto => 'udp', PeerHost => SERVER, PeerPort => $_ ) or die $!; } 8003, 8008, 8019, 8020; for my $svr ( @svrs ) { async { open my $lsn, '<&', fileno( $svr ) or die "$!,/ $^E"; ioctl( $lsn, 0x8004667e, \$noBlock ); while( 1 ) { select'','','',0.1; recv( $lsn, my $in, MAXIN, 0 ); next unless length $in; next if length( $in ) == 1 and ord( $in ) == 25; print "<$in"; } }->detach; } while( sleep 5 ) { $_->send( chr( 1 ) ) for @svrs; }

      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      The start of some sanity?

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