Combining node.js and Python

Question

Node.js is a perfect match for our web project, but there are few computational tasks for which we would prefer Python. We also already have a Python code for them. We are highly concerned about speed, what is the most elegant way how to call a Python "worker" from node.js in an asynchronous non-blocking way?

Answer 1

This sounds like a scenario where zeroMQ would be a good fit. It's a messaging framework that's similar to using TCP or Unix sockets, but it's much more robust (http://zguide.zeromq.org/py:all)

There's a library that uses zeroMQ to provide a RPC framework that works pretty well. It's called zeroRPC (http://www.zerorpc.io/). Here's the hello world.

Python "Hello x" server:

import zerorpc

class HelloRPC(object):
    '''pass the method a name, it replies "Hello name!"'''
    def hello(self, name):
        return "Hello, {0}!".format(name)

def main():
    s = zerorpc.Server(HelloRPC())
    s.bind("tcp://*:4242")
    s.run()

if __name__ == "__main__" : main()

And the node.js client:

var zerorpc = require("zerorpc");

var client = new zerorpc.Client();
client.connect("tcp://127.0.0.1:4242");
//calls the method on the python object
client.invoke("hello", "World", function(error, reply, streaming) {
    if(error){
        console.log("ERROR: ", error);
    }
    console.log(reply);
});

Or vice-versa, node.js server:

var zerorpc = require("zerorpc");

var server = new zerorpc.Server({
    hello: function(name, reply) {
        reply(null, "Hello, " + name, false);
    }
});

server.bind("tcp://0.0.0.0:4242");

And the python client

import zerorpc, sys

c = zerorpc.Client()
c.connect("tcp://127.0.0.1:4242")
name = sys.argv[1] if len(sys.argv) > 1 else "dude"
print c.hello(name)