Publisher Confirms - How to use

[paulohsilvavieira]

Hi! I am create a example with lib for study and practice, but i not found how to get the confirmation, i found only function confirmSelection(), how i get the confirmation on publisher ? I read the code and found confirm.select-ok, but dont found how to use this method

[cody-greene]

Refer to the official (server) documentation for more information on publisher confirms https://www.rabbitmq.com/confirms.html#publisher-confirms

To enable confirms, a client sends the confirm.select method. Depending on whether no-wait was set or not, the broker may respond with a confirm.select-ok. Once the confirm.select method is used on a channel, it is said to be in confirm mode.

The broker then confirms messages as it handles them by sending a basic.ack on the same channel.

You can enable publisher confirms with await channel.confirmSelect(). This library handles publisher confirms automatically, without the need for further user intervention. When you publish a message on a channel in confirm-mode, the await channel.basicPublish(...) call will resolve only when the confirmation (basic.ack) is received.

Full example:

import {Connection} from 'rabbitmq-client'
const rabbit = new Connection()
async function main() {
  const ch = await rabbit.acquire()
  
  await ch.confirmSelect()
  await ch.basicPublish({routingKey: 'foo.bar'}, 'some-example-data')
  await ch.basicPublish({routingKey: 'foo.bar'}, 'some-other-data')
  
  await ch.close()
  await rabbit.close()
}
main()

Throughout this library I have tried to document important behavior where appropriate, and provide links to the official RabbitMQ docs for further context. The relevant notes for this library can be found here:

node-rabbitmq-client/src/Channel.ts

Lines 371 to 376 in 66c822d

	* If publisher-confirms are enabled, then this will resolve when the
	* acknowledgement is received. Otherwise this will resolve after writing to
	* the TCP socket, which is usually immediate. Note that if you keep
	* publishing while the connection is blocked (see {@link Connection.on |
	* Connection.on('connection.blocked')}) then the TCP socket buffer will
	* eventually fill and this method will no longer resolve immediately.

node-rabbitmq-client/src/Channel.ts

Lines 437 to 442 in 66c822d

	/**
	* This method sets the channel to use publisher acknowledgements. The client
	* can only use this method on a non-transactional channel.
	* https://www.rabbitmq.com/confirms.html#publisher-confirms
	*/
	async confirmSelect(): Promise<void> {

Also consider using a higher level "Publisher" object for more safety. rabbit.createPublisher({confirm: true})

node-rabbitmq-client/src/Connection.ts

Lines 190 to 196 in 66c822d

	/**
	* Create a message publisher that can recover from dropped connections.
	* This will create a dedicated Channel, declare queues, declare exchanges,
	* and declare bindings. If the connection is reset, then all of this setup
	* will rerun on a new Channel.
	*/
	createPublisher(props: PublisherProps = {}): Publisher {