[zeromq-dev] ZeroMQ with Python and a basic task

[Michael Cuggy]

Hello,

"On your example, are you running the requisite request receiver, eg
the python script that binds to port 5555 in order that the server can
have something to connect to?"

Yes, I think so.  Can you help me with this as I seem to have made a mistake?

To be honest, I thought it was supposed to run by itself with no other server:

http://zguide.zeromq.org/py:hwclient

The loop back address in the code snippet above made me think it could
be a standalone test.  I have a pair of Linux servers.

One server has this:
http://pastebin.com/nGc36Dq1

A second server has this:
http://pastebin.com/EVzCSKMn

When I run both, I only see this:

Connecting to hello world server...
Sending request 0 ...

It just hangs forever.  I don't think there is a security restriction
preventing the communication.*  But the communication never happens,
so I don't know what is wrong.

thanks,

Mike

* I ran an nmap command to test connectivity on port 5555 on both
servers.  The results indicate that the port isn't being blocked.  It
says "closed" and not "filtered."  Filtered would indicate that the
nmap utility's probe was being dropped.  A probe being dropped means
that a firewall is blocking connectivity on that port.  This is not
the case.  "Closed" indicates a lack of usage but not firewall
blockage.

I therefore don't understand how to get ZeroMQ working using the
Python code on zeromoq.org.


On 3/1/15, Kenneth Adam Miller <kennethadammiller at gmail.com> wrote:
> On your example, are you running the requisite request receiver, eg the
> python script that binds to port 5555 in order that the server can have
> something to connect to? Just checking.
>
> Well it depends on what all you want it to do in what scenario. If these
> are two typical user machines, you might need tcp hole punching to get past
> firewalls to start with. There's libraries for that, and I'll probably go
> through that soon for my application.
>
> Also, you don't have to start from scratch, you could easily work from one
> of the plethora of existing messaging clients and extend them, or at least
> read their source to see how they work.
>
> On Mon, Mar 2, 2015 at 12:29 AM, Michael Cuggy <mcuggy at gmail.com> wrote:
>
>> Hello,
>>
>> I am using RHEL v. 7.x on AWS.  I installed ZeroMQ 4.0.5.  I want to
>> create a basic program using Python and ZeroMQ that serves as a chat
>> service for human users using Linux on a LAN.
>>
>> I have made a significant effort.  I installed the prerequisites for
>> ZeroMQ and ZeroMQ itself. I installed the Python bindings.
>>
>> The problem is that I cannot even get a Hello World program to work on
>> one server.  But I used the Hello World program that was on the
>> zeromq.org page. (http://zguide.zeromq.org/py:hwclient)
>>
>> Here is what I get (after running python hello.py):
>>
>> "Connecting to hello world server
>> Sending request 0"
>>
>> It pauses indefinitely after this.  I have to escape out with Ctrl-c.
>>
>> Can I get step-by-step directions on how to create a messaging program
>> using Python and Zeromq?  I just want it to work between two Linux
>> machines to start with.  It is just problem after problem.  If no one
>> knows of such documentation, can someone please tell me why I cannot
>> see "Hello World" via the Python program that ZeroMQ.org provides?  To
>> me it just
>> pauses after "Sending request 0."
>>
>> thanks,
>>
>> Mike
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>