Ack-mode of shovel

[Muhammad Fathi]

Hi Dears,
I am using RabbitMQ shovel between two clusters, and I am seeking answers to the following:
- what is the actual difference between on-confirm and on-publish modes
if the destination queue is durable and the messages there are persisted?
- I want the message removed from the source queue when the destination broker successfully writes it in the destination queue, not waiting for the consumer to ack it in the destination queue, Just once it's written in the destination queue it gets removed from the source queue, So what mode should I use?

[pvladMQ]

1. " The Shovel's consumer will acknowledge messages automatically on receipt, after (re-)publication, or after confirmation of its publication from the destination server." 

https://docs.vmware.com/en/VMware-RabbitMQ/1.4/vmware-rabbitmq-oci/shovel.html#consumption 

Thus, on-publish acknowledges the messages without needing confirmation, while on-confirm requires confirmation of the publication for the destination server. 

2. On-publish.