From: kingsley@...
Date: 2003-07-01T20:03:44+09:00
Subject: Re: Does Threading work properly?

Hi Brian

Thanks very much for your help - It\'s greatly appreciated.

As you can probably tell I\'m a novice programmer !

Sorry about all the back slashes - the free mail server I use does it
automatically for some odd reason - probably related to security. Have
to switch server.

I\'ll give it a try with sockets

Thanks

Kingsley


On 06-30-2003 09:17 pm, you wrote:

> On Tue, Jul 01, 2003 at 02:07:14AM +0900, kingsley@icecode.org
wrote:
> > require \\\'net/telnet\\\'
> > require \\\'thread\\\'
> 
> Why do you keep putting these backslashes in? It means your code
can\'t be
> pasted in and run :-(
> 
> > thr4 = Thread.new() do
> > loop do
> > tn.cmd(gets.chomp) { |str| print str }
> > end
> > end
> > 
> > thr3 = Thread.new() do
> > loop do
> > tn.waitfor(\\\"Match\\\" => /.+/) { |str| print str }
> > end
> > end
> 
> I have never used the telnet module you are talking about; are you
sure it\'s
> thread-safe? (i.e. you can simultaneously call \"cmd\" and
\"waitfor\" on a
> single instance?)
> 
> Looking at the documentation in the pickaxe, it looks like you\'re
using it
> in the wrong way: if you pass a block to Telnet#cmd then that block
receives
> the results from the server. Hence you have two threads
simultaneously
> trying to read responses from the server, which seems like a bad
thing to
> me.
> 
> You\'d need to do something like:
> 
>   line = gets.chomp
>   tn.cmd( {\'String\'=>line, \'Match\'=>/.+/, Timeout=>5} )
> 
> But even that\'s wrong, because the server could generate multiple
responses
> to one command, but your match on /.+/ would catch only the first
response.
> In other words, the telnet class is only really useful if you know
what
> response to expect from each command. It\'s a kind of poor-man\'s
\"expect\".
> 
> Personally I think you\'d be better of with a raw socket, because
then you
> definitely _can_ send and receive simultaneously:
> 
> require \'socket\'
> require \'thread\'
> 
> sock = TCPSocket.new(\'ftp.tiscali.nl\',21)
> 
> t1 = Thread.new do
>   while line = gets
>     sock.write line
>   end
> end
> t2 = Thread.new do
>   while ch = sock.read(1)
>     putc ch
>   end
> end
> t1.join
> t2.join
> 
> The only thing to beware of is that a true telnet server may send
some odd
> escape sequences as it tries to negotiate some telnet options, but
apart
> from that the above should be fine as a simple telnet client.
> 
> Regards,
> 
> Brian.
> 
> 
>