Google-App-Engine Channel API: Server doesn't send message to client

Question

I've created simple code to understand, how Google App Engine Channel API works. However, actually my code doesn't work and I dont know why. I am not very experienced in Python so pardon me, if it will be some stupid mistake.

Server:

from google.appengine.api import channel

import webapp2
import jinja2
import os
import time

channel_key = 'key'

class MainHandler(webapp2.RequestHandler):
    def get(self):
token = channel.create_channel(channel_key)
        template_values = {'token': channel_key}
        template = env.get_template('index.html')
        self.response.write(template.render(template_values))

class OpenedHandler(webapp2.RequestHandler):
    def post(self):
        channel.send_message(channel_key, "hi")     

env = jinja2.Environment(loader=jinja2.FileSystemLoader(os.path.dirname(__file__)))     
app = webapp2.WSGIApplication([
    ('/', MainHandler),
    ('/opened', OpenedHandler)
], debug=True)

Client:

<!DOCTYPE html>

<html>
    <head>
    </head>
    <body>
        <script>
            var token = "{{ token }}";
            onOpened = function() {
                var xhr = new XMLHttpRequest();
                xhr.open('POST', '/opened');
                xhr.send();
            };

            onMessage = function(message) {
                alert("something recieved");
                alert(message);
            }
        </script>
        <script type="text/javascript" src="/_ah/channel/jsapi"></script>
        <script>
            channel = new goog.appengine.Channel(token);
            socket = channel.open();
            socket.onopen = onOpened;
            socket.onmessage = onMessage;
            socket.onerror = function(e){
                alert("error:"+e['description']);
            };
            socket.onclose = function(){
                alert("close");
            };

        </script>
    </body>
</html>

Javascript console says, that it was successfully sended to /opened, but then no alert comes, like it havent responded. Do you have any idea, where the problem is?

Thanks Toneks

EDIT: I added onerror and onclose event handlers to javascript and immediately after opnening the page it calls onerror event saying "Invalid+token" and then onclose event.

I am not even to create channel. Can you please answer this stackoverflow.com/questions/34332222/… — Sunil Garg

Moishe Lettvin Moishe Lettvin · Accepted Answer · 2013-06-08T15:44:46

I'll bet if you log your channel_key it'll be different when you create the channel and when you send the message. For this exercise you could just use a constant; for "real" code you'll want to use the datastore and memcache for your channel keys.

Google-App-Engine Channel API: Server doesn't send message to client

1 Answers