Declare a queue, bind the queue to an exchange.
A first approach was to connect to the broker at server start,
a channel, then to interact with the channel when requests come.
This approach isn't optimal as:
- channel can be closed by errors like a non existing exchange
- we want to recover if the broker restarts
- the pika loop and the Werkzeug loop could behave differently
So each request will open/close a connection to the broker.
Ref T1210