CODEWITHSUNDEEP
javascriptpythongoogle-app-enginegoogle-chrome-extensionchannel
shayuna
shayuna

Reputation: 484

using the channel google app engine from within a chrome extension

here is the code that runs in the extension, in the background.html.

function onLoad()
{

    var path="http://localhost:8082/index.htm?key=1234";
    xhr.open('get', path, false);
    xhr.send();
    token=xhr.responseText;
    caughtMsg=token+" *** ";
    var channel = new goog.appengine.Channel(token);
    var handler = {
      'onopen': function(){caughtMsg+=" *** open";},
      'onmessage': onMessage,
      'onerror': function(e){caughtMsg+=" *** err "+e.description+" "+e.code},
      'onclose': function(){caughtMsg+=" *** close";}
    };
    var socket = channel.open(handler);
    socket.onmessage = onMessage;

}

it interacts with a localhost server script (in python) that creates a channel and returns a token. then the token is used to create the channel object on the client side. instead, what i get from the aggregate responses is:

channel-354645736-1234 * err invalid+token 401 * close

when i do it outside the extension scope (not using ajax to establish the connection) it works like a charm.

where do i go astray ?

Upvotes: 3

Views: 1622

Answers (1)

x29a
x29a

Reputation: 1781

As i see from your comment, you had problems testing the channel API on your local development system.

It worked for me, when i downloaded the channel.js (instead of using http://*.appspot.com/_ah/channel/jsapi) and used a local copy on the background script

<script type="text/javascript" src="/lib/channel.js"></script>

In the channel.js, change the line definining

goog.appengine.DevSocket.BASE_URL = "http://localhost:8080/_ah/channel/";

to represent your local environment (port for appengine testserver)

Also, the URL you send your xhr.open to must be in your manifests "permission" section, in my case

"permissions":
  [
    ...,
    "http://localhost:8080/"
  ]

The tokens generated by your local appengine testserver differ from the ones in the livesystem, so its not possible to mix the two.

Upvotes: 2

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