[EnMasse] AMQP Client reconnect

[Klump Vico (INST/ECS4)]

Hi Gordon,

thanks for your detailed response!

For topics: What are the steps to reestablish a link for a durable subscription? Proton example? 
If it exists, could you please point me to the GitHub ticket to automatically handle that?


Best regards
Vico

(INST/ECS4) 
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-----Ursprüngliche Nachricht-----
Von: enmasse-bounces at redhat.com [mailto:enmasse-bounces at redhat.com] Im Auftrag von Gordon Sim
Gesendet: Montag, 25. September 2017 15:36
An: enmasse at redhat.com
Betreff: Re: [EnMasse] AMQP Client reconnect

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.

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