simple python comet client

simplecometclient.py

import email.utils # for rfc2822 formatted current timestamp
import requests

class CometClient(object):

	def __init__(self, last_modified=None):
		if last_modified is None:
			self.last_modified = email.utils.formatdate()
		else:
			self.last_modified = last_modified
		self.etag = 0

	def listen(self, url):
		while True:
			self._get_request(url)

	def _get_request(self, url):
		try:
			resp = requests.get(url, headers={
					'If-None-Match': str(self.etag),
					'If-Modified-Since': str(self.last_modified)})
			self.last_modified = resp.headers['Last-Modified']
			self.etag = resp.headers['Etag']
			self.handle_response(resp.content)
		except requests.exceptions.Timeout:
			pass

	def handle_response(self, response):
		print response

if __name__ == '__main__':

	import sys
	comet = CometClient()
	comet.listen(sys.argv[1])

I have tried to use this in different ways, but without success. I am connecting to a tornado comet server.

python simplecometclient.py localhost:8888/realtime/mygroup
requests.exceptions.InvalidSchema: Invalid scheme 'localhost'

python simplecometclient.py http://localhost:8888/realtime/mygroup
Can "Upgrade" only to "WebSocket".

python simplecometclient.py ws://localhost:8888/realtime/mygroup
requests.exceptions.InvalidSchema: Invalid scheme 'ws'

So how can I use this?

I guess I should have been more specific: this code doesn't work with websockets—it's for long-poll style Comet connections provided by, e.g., the nginx http push module (http://pushmodule.slact.net/). here are some good leads on Python websocket clients: http://stackoverflow.com/questions/3142705/is-there-a-websocket-client-implemented-for-python

Thanks for your prompt reply. Actually I am doing comet, not ws. I have tried the ws:// schema just because this is what the jquery part of the application is trying while establishing the conection to tornado. But I am pretty confident that the tornado server is doing comet, not web sockets (well, I am just reasonably confident). Could you provide an example of how you are using your script in your particular situation? Maybe some output would also be useful.

I have opened a StackOverflow question regarding this issue. You can see it here: http://stackoverflow.com/questions/11141618/simple-comet-client-in-python