Exchange Federation is no longer configured using exchange declaration.
Federation: Pre 3.0 Configuration lives in the configuration file. You must ensure all nodes in a cluster have the same configuration. The broker must be restarted for changes to take effect. Federated exchanges are of a special type, and must be declared as such by AMQP clients.
Federation: 3.0 Configuration is stored in the broker database, manipulated with rabbitmqctl or the management plugin. All nodes in a cluster automatically have the same configuration. Changes to federation take effect immediately. Federated exchanges are transparent to clients; exchanges can become federated at any time.
Previously, if the consumer failed to start within 60 seconds it was considered fatal. If the server is down and the network is configured to take more than 60 seconds to report dropped SYN (socket open) packets, the context would fail to initialize.
This is not consistent with, say, when the server is up but the broker is down. In that case, the connection failure is detected immediately, and the consumer starts attempting to reconnect - it is NOT considered a fatal exception.
This change removes the fatal exception thrown when the consumer fails to start in the 60 seconds (while still waiting for up to 60 seconds to see if a real fatal exception occurred).
Note that a real fatal exception (such as failure to declare the queue(s) passively) will still cause the context to fail to initialize, if it occurs within 60 seconds of the consumer starting.