pynng 0.2.0

Networking made simply using nng

This is pynng.

Ergonomic bindings for nanomsg next generation (nng), in Python. pynng provides a nice interface on top of the full power of nng. nng, and therefore pynng, make it easy to communicate between processes on a single computer or computers across a network.

Goals

Provide a Pythonic, works-out-of-the box library on Windows and Unix-y platforms. Like nng itself, the license is MIT, so it can be used without restriction.

Installation

On Windows and 64-bit Linux, the usual

pip install pynng

should suffice. Building from source is a little convoluted, due to some issues with the way the setup.py script is written. Nevertheless, it can be done:

git clone https://github.com/codypiersall/pynng
cd pynng
pip install .
python setup.py build
python setup.py build_ext --inplace
pytest

Installing on Mac

This project does not yet know how to build for Mac, because I don't have a Mac to test on. The tricky bit is letting cffi know the correct object file to link to, and ensuring whatever the Mac equivalent of -fPIC is set when compiling.

Using pynng

Using pynng is easy peasy:

from pynng import Pair0

s1 = Pair0()
s1.listen('tcp://127.0.0.1:54321')
s2 = Pair0()
s2.dial('tcp://127.0.0.1:54321')
s1.send(b'Well hello there')
print(s2.recv())
s1.close()
s2.close()

Since pynng sockets support setting most parameters in the socket's __init__ method and is a context manager, the above code can be written much shorter:

from pynng import Pair0

with Pair0(listen='tcp://127.0.0.1:54321') as s1, \
        Pair0(dial='tcp://127.0.0.1:54321') as s2:
    s1.send(b'Well hello there')
    print(s2.recv())

Using pynng with an async framework

Asynchronous sending also works with

trio and asyncio. Here is an example using trio:

import pynng
import trio

async def send_and_recv(sender, receiver, message):
    await sender.asend(message)
    return await receiver.arecv()

with pynng.Pair0(listen='tcp://127.0.0.1:54321') as s1, \
        pynng.Pair0(dial='tcp://127.0.0.1:54321') as s2:
    received = trio.run(send_and_recv, s1, s2, b'hello there old pal!')
    assert received == b'hello there old pal!'

Many other protocols are available as well:

• Pair0: one-to-one, bidirectional communication.
• Pair1: one-to-one, bidirectional communication, but also supporting polyamorous sockets
• Pub0, Sub0: publish/subscribe sockets.
• Surveyor0, Respondent0: Broadcast a survey to respondents, e.g. to find out what services are available.
• Req0, Rep0: request/response pattern.
• Push0, Pull0: Aggregate messages from multiple sources and load balance among many destinations.

TODO

• Support Mac
• More docs