README.md

Getting Started

$ pip install falcon
$ python3 app.py

alternatively with Gunicorn (for HTTP/1.1):

$ pip install gunicorn
$ gunicorn app:app

aggregator.py

from asyncio import Future, Task, coroutine as async, sleep
from random import randint


def retrieve(*uris, callback=None):
    res = Future()
    responses = []

    def conclude(response):
        responses.append(response)
        if callback:
            # The socket being written needs bytes not strings
            callback(response.encode('utf-8'))
        if len(responses) == len(uris):
            res.set_result(responses)

    for uri in uris:
        task = Task(fetch(uri))
        task.add_done_callback(lambda task: conclude(task.result()))

    return res


@async
def fetch(uri):
    print("retrieving %s..." % uri)
    lag = yield from _http()
    lag = lag * 1000
    print("downloaded %s in %d ms" % (uri, lag))
    return "[%d ms] %s\n" % (lag, uri)


@async
def _http():
    lag = randint(2, 9) # delay long enough to notice
    yield from sleep(lag)
    return lag

app.py

import asyncio
from wsgiref import simple_server

import aggregator

def on_get(environ, start_response):
    """RAW WSGI for the win!"""
    uris = ("http://example.org/foo", "http://example.org/bar",
            "http://example.org/baz")

    writeable = start_response('200 OK', [])
    service_requests = aggregator.retrieve(*uris, callback=writeable)
    loop = asyncio.get_event_loop()
    loop.run_until_complete(service_requests)

    # despite us using writeable we need to return an empty iterator
    return []


app = on_get

if __name__ == "__main__":
    server = simple_server.make_server("localhost", 8000, app)
    server.serve_forever()