GAE/J Channel API exception even though messages go through?
I open a channel during the app initialization through a series of ajax calls:
getToken = function () {
xhr = new XMLHttpRequest();
xhr.open("GET", "/game?action=getChannelToken", true);
xhr.send(null);
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status==200) {
connect(xhr.responseText);
}
};
};
Servlet:
ChannelService channelService = ChannelServiceFactory.getChannelService();
channelToken = channelService.createChannel(uid);
The token is then returned to the ja开发者_Python百科vascript for:
connect = function (token) {
// alert ("connect");
var channel = new goog.appengine.Channel(token);
var socket = channel.open();
socket.onopen = onOpened;
socket.onmessage = onMessage;
socket.onerror = onError;
socket.onclose = onClose;
};
I'm getting this error:
WARNING: /_ah/channel/dev com.google.appengine.api.channel.dev.LocalChannelFailureException: Channel for application key null not found.
The channel creation part is very simple, so I do not understand where is the problem.
System.out.println (channelToken);
returns something like
channel--rrmk8i-100002139544068
(100002139544068 is the uid I used to create the channel), so it seems to return a real token. Moreover, channelService.sendMessage(msg);
(using the same uid as before), sends the message without any problem.
Does anyone have any idea why this is happening? I'm using eclipse 3.5.2, GAE/J 1.4.2 and ubuntu 10.10
Googling for that exception I found only one discussion here: http://groups.google.com/group/google-appengine-java/browse_thread/thread/19f250b1ff0e4342
but changing var channel = new goog.appengine.Channel(token);
to var channel = new goog.appengine.Channel(uid);
did not solve anything (and, from what I understand, it shouldn't)
I can think of two reasons this could be happening:
You're restarting the dev_appserver.py while your client is still running. Because the client will be polling with an "old" token that the dev_appserver doesn't know about, it will throw this error. If this is the case, just refresh your client page after restarting the dev_appserver (or otherwise force it to request a new token).
connect() is being called with an invalid token. It sounds like you've ruled that out but if the above isn't true it might be worth double-checking.
You can see what token the client is polling with you can open up Firebug or the Chrome dev console and look for requests to a path like this:
http://localhost:8080/_ah/channel/dev?command=poll&channel=channel-1503856530-alpha-token&client=1
The channel-1503856530-alpha-token
part of that URL is the token passed to "new goog.appengine.Channel()
".
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