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Re: [newbie] trying socket as a replacement for nc

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On Thu, Dec 12, 2013 at 12:28 AM, Jean Dubois <jeandubois314@gmail.com> wrote:
> On Thursday, December 12, 2013 12:20:36 AM UTC+1, Dan Stromberg wrote:
>> On Wed, Dec 11, 2013 at 3:08 PM, Jean Dubois <jeandu...@gmail.com> wrote:
>>
>> I have an ethernet-rs232 adapter which allows me to connect to a measurement instrument by means of netcat on a linux system.
>>
>>
>> e.g. entering nc 10.128.59.63 7000
>>
>> allows me to enter e.g.
>>
>> *IDN?
>>
>> after which I get an identification string of the measurement instrument back.
>>
>> I thought I could accomplish the same using the python module "socket"
>>
>> and tried out the sample program below which doesn't work however:
>>
>>
>>
>> Sockets reserve the right to split one socket.send() into multiple socket.recv()'s on the other end of the communication, or to aggregate multiple socket.send()'s into a single socket.recv() - pretty much any way the relevant IP stacks and communications equipment feel like for the sake of performance or reliability.
>>
>>
>> The confusing thing about this is, it won't be done on every transmission - in fact, it'll probably happen rather seldom unless you're on a heavy loaded network or have some MTU issues (see Path MTU Discovery, and bear in mind that paths can change during a TCP session).  But writing your code assuming it will never happen is a bad idea.
>>
>>
>>
>> For this reason, I wrote http://stromberg.dnsalias.org/~strombrg/bufsock.html , which abstracts away these complications, and actually makes things pretty simple.  There are examples on the web page.
>>
>>
>>
>> HTH
>
> Dear Dan,
> Could you copy paste here the code for your function I have to add to my "program"?

This is untested, but it should be something like the following:

#!/usr/bin/env python

"""
A simple echo client
"""
import socket as socket_mod
import bufsock as bufsock_mod
host = '10.128.59.63'
port = 7000
size = 10
socket = socket_mod.socket(socket.AF_INET, socket.SOCK_STREAM)
socket.connect((host,port))
bufsock = bufsock_mod.bufsock(socket)
bufsock.send('*IDN?')
data = bufsock.recv(size)
bufsock.close()
print 'Received:', data

You might look over
http://stackoverflow.com/questions/19918307/retrieve-file-information-located-on-a-different-application-server-using-python/19918706#19918706
for a more complete example.

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[newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-11 15:08 -0800
  Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-11 15:20 -0800
    Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 00:28 -0800
      Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 13:23 -0800
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 19:23 -0800
          Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 19:32 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 03:03 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 03:56 -0800
          Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-13 08:35 +0000
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 04:20 -0800
              Re: [newbie] trying socket as a replacement for nc rusi <rustompmody@gmail.com> - 2013-12-13 09:04 -0800
              Re: [newbie] trying socket as a replacement for nc rusi <rustompmody@gmail.com> - 2013-12-13 09:09 -0800
                Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-14 05:11 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-14 05:14 -0800
              Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-14 13:29 +0000
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-16 01:40 -0800
          Re: [newbie] trying socket as a replacement for nc Ervin Hegedüs <airween@gmail.com> - 2013-12-16 11:04 +0100
    Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-12 14:16 +0000
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-13 01:23 +1100
      Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 13:27 -0800
        Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:06 +0000
          Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-14 17:24 -0800
            Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-15 15:15 +0000
              Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-15 10:51 -0500
                Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 03:04 +1100
                Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-15 12:44 -0500
                Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-15 22:42 +0000
                Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 09:48 +1100
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-13 08:58 +1100
        Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:10 +0000
          Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-14 03:19 +1100
            Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:57 +0000
              Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-14 04:05 +1100
        Re: [newbie] trying socket as a replacement for nc 88888 Dihedral <dihedral88888@gmail.com> - 2013-12-16 04:38 -0800
          Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 23:59 +1100
          Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-16 09:03 -0500
            Re: [newbie] trying socket as a replacement for nc 88888 Dihedral <dihedral88888@gmail.com> - 2013-12-18 23:20 -0800
      Re: [newbie] trying socket as a replacement for nc Dave Angel <davea@davea.name> - 2013-12-12 19:52 -0500
  Re: [newbie] trying socket as a replacement for nc Conor Hughes <conorh@conorh.net> - 2013-12-11 15:38 -0800
    Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 00:08 -0800
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-12 19:21 +1100
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 01:21 -0800
          Re: [newbie] trying socket as a replacement for nc Alister <alister.ware@ntlworld.com> - 2013-12-12 14:05 +0000
          Re: [newbie] trying socket as a replacement for nc Alister <alister.ware@ntlworld.com> - 2013-12-12 14:05 +0000
            Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-12 14:34 +0000
  Re: [newbie] trying socket as a replacement for nc Christian Gollwitzer <auriocus@gmx.de> - 2013-12-13 00:43 +0100

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