Message failure in channel api - google-app-engine

Question

I am running a gae web app on localhost.
I have successfully generated a token from goog.channel and send it to client. Where client is able to accept the token and tries to open connection. The problem is that, I am sending a message from my servlet class and nothing is happening in client side.
Below are my codes:
Server Side:
//for generating token
ChannelService channelService=ChannelServiceFactory.getChannelService();
token = channelService.createChannel(userid);
//for sending message
ChannelService channelService=ChannelServiceFactory.getChannelService();
channelService.sendMessage(new ChannelMessage(userid, message));
//in appengine-web.xml
<inbound-services>
<service>channel_presence</service>
</inbound-services>
Javascript:
function getToken(){
var xmlhttpreq=new XMLHttpRequest();
xmlhttpreq.open('GET',host+'/channelapi_token?q='+user,false);
xmlhttpreq.send();
xmlhttpreq.onreadystatechange=alert(xmlhttpreq.responseText);
token=xmlhttpreq.responseText;
setChannel();
}
function setChannel(){
alert(token);//iam receiving right token here
channel=new goog.appengine.Channel(token);
socket=channel.open();
socket.open=alert('socket opened');//this message alerts
socket.onmessage=alert('socket onmessage');//this message alerts
socket.onerror=alert('socket onerror');//this message alerts
socket.onclose=alert('socket onclose');//this message alerts
}
There are no exceptions while sending message from channelservice.
Also the client side is repeatly making a get request to my server:
http://localhost:8888/_ah/channel/dev?command=poll&channel=channel-h1yphg-vivems#gmail.com&client=connection-3
What's the wrong happening here?
Thanks in advance.

Answer 1

You're calling alert(...) and assigning its return value to your message handlers. You should assign a function to these handlers instead:
socket.onopen = function() {
alert('socket opened');
};
// etc
// Note that message takes a parameter:
socket.onmessage = function(evt) {
alert('got message: ' + evt.data);
};
Note you can also do this like:
function onMessage(evt) {
// do something
}
socket.onmessage = onMessage;
Note that you're not assigning onMessage(), which will call onMessage and assign its return value.