[EnMasse] AMQP Client reconnect

[Gordon Sim]

On 25/09/17 14:11, Klump Vico (INST/ECS4) wrote:
> Hi,
> 
> how is an AMQP client reconnect handled in EnMasse
> 
> for brokered messages? Are AMQP client connections attached to
> 
> a session that’s reestablished after reconnect?

No. In AMQP it is links that would be re-established rather than sessions.

At present enmasse gives an 'at-least-once' guarantee for anycast, queue 
and topic and an at-most-once guarantee for multicast.

For anycast and queue, there is no special handling of reconnections. 
These both use message routing. Any in-doubt messages on the producers 
side should be republished. In the case of queues, where there is a 
store-and-forward guarantee, any in-doubt messages on the receiving side 
will be resent by the broker(s).

For topics, which use link routing, there is at present an extra step 
required to re-establish a link for a durable subscription. This uses 
the AMQP link redirect mechanism to point the subscriber at the broker 
which holds its subscription. The plan is to make this extra step 
unnecessary by having the system automatically handle the routing of the 
link on reconnection.