Sending raw bytes over ZeroMQ in Python

Question

I'm porting some Python code that uses raw TCP sockets to ZeroMQ for better stability and a cleaner interface.

Right off the bat I can see that a single packet of raw bytes is not sent as I'm expecting.

In raw sockets:

import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.send('\x00\x01\x02 and some more raw bytes')

Which is the current working code. This is the same code using ZeroMQ:

import zmq
context = zmq.Context()
sock = context.socket(zmq.REQ)  # this connection utilizes REQ/REP
sock.connect('tcp://{0}:{1}'.format(HOST, PORT))
sock.send('\x00\x01\x02 and some more raw bytes')

But when I inspect the packets going over the net, they're definitely not what I'm expecting. What am I missing here?

Also, when testing this code on the loopback interface (127.0.0.1) with a dummy server it seems to work just fine.

Using Python 2.7 if it matters (unicode or whatnot).

There is no output, I'm inspecting the raw network traffic, is that what you're looking for? — Yuval Adam
– Yuval Adam, Commented Sep 27, 2012 at 13:10
zeromq uses it's own data marshaling on sockets; if you sniff the packets, they don't have to be exactly the same — Bartek Banachewicz
– Bartek Banachewicz, Commented Sep 27, 2012 at 13:49
@BartekBanachewicz - very true, thanks. Notice my answer from just now. — Yuval Adam
– Yuval Adam, Commented Sep 27, 2012 at 13:50

Yuval Adam · Accepted Answer · 2012-09-27 13:50:07Z

4

Oh. Wow. I overlooked a major flaw in my test, the remote server I was testing on was expecting a raw TCP connection, not a ZMQ connection.

Of course ZMQ wasn't able to transfer the message, it didn't even negotiate the connection successfully. When I tested locally I was testing with a dummy ZMQ server, so it worked fine.

If I'd have posted the server code it would have immediately made sense that that was the problem.

In any case, sorry for the false alarm.

answered Sep 27, 2012 at 13:50

Yuval Adam

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