SDK channel_service_stub.py Removing channel in some responses

[ehono]

Hi there,

I'm having some issues when sending messages from server to a client
through a channel (GAE python SDK)

Usually there aren't problems and when a message is sent from the
server to the client, the client is able to pick it up:

...
DEBUG 2011-07-18 16:14:53,800 channel_service_stub.py:105] Creating
channel token channel-2384468497-BT01 with client id BT01
...
DEBUG 2011-07-18 16:14:59,682 dev_appserver.py:569] Matched "/_ah/
channel/dev?command=connect&channel=channel-2384468497-BT01" to
<google.appengine.tools.dev_appserver_channel.ChannelDispatcher object
at 0xace3e8c> with path
DEBUG 2011-07-18 16:14:59,710 dev_appserver.py:4215] "GET /_ah/
channel/dev?command=connect&channel=channel-2384468497-BT01 HTTP/1.1"
200 -
DEBUG 2011-07-18 16:14:59,713 dev_appserver_index.py:172] No need
to update index.yaml
... [there is something in the channel]
DEBUG 2011-07-18 16:15:01,147 dev_appserver.py:569] Matched "/_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1" to
<google.appengine.tools.dev_appserver_channel.ChannelDispatcher object
at 0xada5cac> with path
DEBUG 2011-07-18 16:15:01,148 channel_service_stub.py:187] Checking
for messages on channel (channel-2384468497-BT01) (True)
DEBUG 2011-07-18 16:15:01,151 channel_service_stub.py:187] Checking
for messages on channel (channel-2384468497-BT01) (True)
DEBUG 2011-07-18 16:15:01,152 channel_service_stub.py:202] Popping
first message of queue for channel (channel-2384468497-BT01)
DEBUG 2011-07-18 16:15:01,187 dev_appserver.py:4215] "GET /_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1 HTTP/
1.1" 200 -
... [nothing in the channel]
DEBUG 2011-07-18 16:15:02,494 dev_appserver.py:569] Matched "/_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1" to
<google.appengine.tools.dev_appserver_channel.ChannelDispatcher object
at 0xada952c> with path
DEBUG 2011-07-18 16:15:02,495 channel_service_stub.py:187] Checking
for messages on channel (channel-2384468497-BT01) (False)
DEBUG 2011-07-18 16:15:02,530 dev_appserver.py:4215] "GET /_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1 HTTP/
1.1" 200 -
...

But some times, with some kind of responses the channel is removed and
the client is not able to retrieve the message and then process it:

... [some contents should be in the channel]
DEBUG 2011-07-18 16:15:10,282 channel_service_stub.py:278] Removing
channel BT01
WARNING 2011-07-18 16:15:10,308 dev_appserver.py:4081] Request to /
_ah/channel/disconnected/ excluded because channel_presence is not
enabled in inbound_services in app.yaml
INFO 2011-07-18 16:15:10,309 dev_appserver.py:4217] "POST /_ah/
channel/disconnected/ HTTP/1.1" 404 -
DEBUG 2011-07-18 16:15:10,997 dev_appserver.py:569] Matched "/_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1" to
<google.appengine.tools.dev_appserver_channel.ChannelDispatcher object
at 0xacdfb8c> with path
DEBUG 2011-07-18 16:15:10,998 channel_service_stub.py:187] Checking
for messages on channel (channel-2384468497-BT01) (False)
DEBUG 2011-07-18 16:15:11,021 dev_appserver.py:4215] "GET /_ah/
channel/dev?command=poll&channel=channel-2384468497-BT01&client=1 HTTP/
1.1" 200 -
...

The really curious thing is, when deploying the app to GAE everything
works fine. I suppose there is being some kind of exception while
picking up the message, but i don't know how to trace it to try to fix
it.

Any suggestion in this matter?

Regards

[ehono]

Ok, finally I discovered what was happening... This is the code causing the problem:

...

myobj.sendMessage(data);

alert('some 'message');

...

So the first sentence calls a method sending some objects (JSON formatted) through a channel, and the second one shows an alert to trace my app.

Removing the alert fix the behavior I detailed in my previous message.

I hope this helps to someone in the future!

Regards!