HTTP Tutorial

Disclaimer

Unlike most HTTP servers out there zerogw doesn’t try to support old CGI convention of passing environment to your web application. For each forwarded requests zerogw forwards only a few fields, such as url and method (configurable) to a backend. This way we produce less internal traffic and less bloated applications. This also means thay you can’t use most of bloated web frameworks out there. Zerogw is suitable for fast web applications (and a parts of thereof) which need most out of machine performance (e.g. you can use it for autocompletion or some other AJAX). If you want to use big fat web framework there are plenty of other solutions. If thats ok for you, read on!

Hello World

Let’s start with simple hello world application. The first thing to know is how to configure zerogw. We will start with simplest possible configuration and will improve it later.

Minimal configuration:

Server:
  listen:
    host: 0.0.0.0
    port: 8080

Routing:
  zmq-forward:
    enabled: yes
    socket:
    - !zmq.Bind "tcp://127.0.0.1:5000"
    contents:
    - !Uri

All above means that zerogw will listen for connections on port 8080 on all interfaces (0.0.0.0). Then it will forward requests to local host with port 5000. This port also listens for connections, so you can start several backend processes (and even several boxes, if you’ll change 127.0.0.1 to your local network ip address) to process requests. Forwarded request will contain just URI part of the original request.

Then we will write a simple script which would make this work:

import zmq

ctx = zmq.Context()
sock = ctx.socket(zmq.REP)
sock.connect('tcp://127.0.0.1:5000')
while True:
    uri, = sock.recv_multipart()
    sock.send_multipart([b'Hello from '+uri])

This is everything which is needed to serve requests. Note we are connecting to the address you specified to bind to in zerogw config. Now you can go to the browser at http://localhost:8080/ and you should see Hello from /.

We use recv_multipart and send_multipart to simplify working with sockets. If they are not provided in your language bindings you will probably need to use recv and send while reading RCVMORE and setting SNDMORE flags. Refer to zeromq and you language bindings for more information.

Note

This code works perfectly for example, but in reality it can except suring recv or send calls. So in production application you should use more complicated loop. See ioloop in pyzmq bindings or appropriate functionality in your language bindings

Was that hard? I guess no really.