The general flow of MQTT is: producer ---> MQTT Broker ---> consumer.Assume that the MQTT Broker is always up and running but consumer is temporarily unavailable.
If a producer sends a message to a MQTT broker with QoS 1, does the broker send an acknowledgement back to the producer since the broker did receive the message?
If a producer sends one message to a broker with QoS 1, the broker will keep trying to deliver message to the consumer. If the producer sends more messages, will the broker keep retrying to send the first message to the consumer? Does this mean that messages will be queued up in the broker? How long will the broker retry delivering a message to a consumer before moving on to the next message?
If a producer sends one message to a broker with QoS 2, will the broker keep retrying indefinitely since QoS 2 guarantees exactly one delivery?