Inbound Endpoint Acknowledge Mode

By default, the inbound endpoints use the AUTO acknowledge mode, which means the container automatically acknowledges the message when the downstream integration flow completes (or a message is handed off to another thread by using a QueueChannel or ExecutorChannel). Setting the mode to NONE configures the consumer such that acknowledgments are not used at all (the broker automatically acknowledges the message as soon as it is sent). Setting the mode to MANUAL lets user code acknowledge the message at some other point during processing. To support this, with this mode, the endpoints provide the Channel and deliveryTag in the amqp_channel and amqp_deliveryTag headers, respectively.spring-doc.cn

You can perform any valid Rabbit command on the Channel but, generally, only basicAck and basicNack (or basicReject) are used. In order to not interfere with the operation of the container, you should not retain a reference to the channel and use it only in the context of the current message.spring-doc.cn

Since the Channel is a reference to a “live” object, it cannot be serialized and is lost if a message is persisted.

The following example shows how you might use MANUAL acknowledgement:spring-doc.cn

@ServiceActivator(inputChannel = "foo", outputChannel = "bar")
public Object handle(@Payload String payload, @Header(AmqpHeaders.CHANNEL) Channel channel,
        @Header(AmqpHeaders.DELIVERY_TAG) Long deliveryTag) throws Exception {

    // Do some processing

    if (allOK) {
        channel.basicAck(deliveryTag, false);

        // perhaps do some more processing

    }
    else {
        channel.basicNack(deliveryTag, false, true);
    }
    return someResultForDownStreamProcessing;
}