Re: How to clean up socket connection to printer

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From	Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com>
Newsgroups	comp.lang.python
Subject	Re: How to clean up socket connection to printer
Date	Tue, 09 Jul 2013 16:05:08 +0200
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Am 09.07.2013 11:39, schrieb loial:
> I have a socket application that is connecting to a HP printer via port 9100.
>
> Occassionally I get a "Connection reset by peer" error which I am
> trapping and exiting the script with an error message.

Strange. Why does the remote terminate the connection?


> That works Ok, the issue I have is that the next time I run the
> script  I get "Connection refused" from the printer, which
 > suggests that the printer still thinks the port is is busy,
 > though nothing is printing. I suspect that in some way my socket
 > connection has not been closed correctly?

I'm assuming you are using TCP. Getting a "connection refused" rather 
means that there is no server process that is listening on that port. It 
sounds a bit as if the printer was kind-of rebooting itself, which first 
resets the existing connection and then, after a rebooting, opens the 
port again for connections.

Question here:
1. Does the printer accept connections again after some time?
2. Does the printer accept connections if you close and re-open the 
Python interpreter?
3. Is there actually a limit to the number of concurrent connections? In 
other words, what happens when you try to create a second connection 
without closing the first?


> When I get the "Connection rest by peer" error, I attempt to close
> the  port as follows :
[...]

This is useless, the connection is already closed at that point.


Your description suggests that it is a remote problem. I still wouldn't 
rule out that it is somehow caused by your code though, but without 
seeing that, it's impossible to tell.

Good luck!

Uli

Thread

How to clean up socket connection to printer loial <jldunn2000@gmail.com> - 2013-07-09 02:39 -0700
  Re: How to clean up socket connection to printer Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-07-09 16:05 +0200
  Re: How to clean up socket connection to printer loial <jldunn2000@gmail.com> - 2013-07-11 02:28 -0700
    Re: How to clean up socket connection to printer Chris Angelico <rosuav@gmail.com> - 2013-07-11 20:13 +1000
  Re: How to clean up socket connection to printer loial <jldunn2000@gmail.com> - 2013-07-15 04:22 -0700

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