txamqp-user team mailing list archive

[Aurélien Bompard <aurelien.bompard@xxxxxx>]

Hello *,

I opened a bug[1] yesterday about error handling in txamqp, but as I'm 
investigating further, I wonder if it's really a bug, or if I'm just 
doing it wrong.

[1] https://bugs.launchpad.net/txamqp/+bug/956132

Here's the scenario. I call basic_publish on a non-existent exchange. 
I'd like to catch the error and log it.
If I understand correctly, when I basic_publish to a non-existant 
exchange, the basic_publish call succeeds, and then the servers sends a 
channel_close() method to the client, with the following message :
(404, "NOT_FOUND - no exchange 'fake.exchange' in vhost '/'", 60, 40)
Then the client replies with close-ok(), and the channel is closed, no 
more messages can be sent.

It looks like I can't detect that before the next action on the channel 
(publish, close, anything), which will raise a Closed exception. Is 
there any way to catch it sooner ? The optimal way would be, in my mind, 
to have the basic_publish deferred call the errback chain, but I guess 
that's just not possible with the current AMQP spec. Or is it ?

Then, I'd like to open another channel (channel re-opening is forbidden 
by the spec) for the next operations, but I wonder how many channels I'm 
allowed to open here. They are all stored in the AMQClient.channel dict, 
which may grow out of hand if a message is repeatedly causing a 
channel_close.

And in general, I'd love to get some advice on the recommended way to do 
error handling with txAMQP. Experience and real-case situations are 
welcomed too.

Thanks a lot !

Aurélien

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