Using Google Appengine Channel API with a Python Client

For a project, I  needed a way to perform long-poll requests with GAE. Just using a normal connection doesn't work because of the 30-Seconds request limit GAE enforces. But starting with Version 1.4 Google released the Google Appengine Channel API which allows long-pull requests with a javascript client library.
It's quite easy to use. create a channel:

from google.appengine.api import channel
token = channel.create_channel(chan_name)

And start sending messages:

channel.send_message(chan_name, msg)


Unfortunately, there is neighter any non-javascript client library for use in desktop applications, nor is there any specifications of the protocol available. So I reverse-engineered the javascript-client and created a python client implementation. Feel free to use it. But be aware that although it seems to work quite well,  it's not well tested yet. I've not yet used it on a real-world application. Be also aware that google could change the underlying protocol without any notice, which would obliviously break this library.

Use it like this:

import gae_channel

channel = gae_channel.Client(token='your channel token')
for msg in chan.messages():
    print msg 

Also have a look at /demo. There's a small demo client available.

$ python receiver.py 
Your channel name is: fWVwdXvNJP
now run in an other terminal:
python sender.py fWVwdXvNJP
I'm now listening for messages, dont close this terminal...

Now in another terminal, run:

$ python sender.py fWVwdXvNJP
Enter a message:test

Now you'll see the message appearing in the first terminal.

Download from bitbucket.