Message Quality of Service
Messages can be classified as Persistent (Guaranteed) or Non-Persistent (Direct) by the message producer.
Guaranteed messages are spooled to non-volatile storage on the broker, and are kept until the broker has verified the successful delivery of those messages to all clients and downstream event brokers.
Direct messages are delivered to subscribing clients in the order in which producers publish them. They are not spooled to non-volatile storage, and do not require acknowledgment.
Guaranteed messages are spooled to non-volatile storage on the broker, and are kept until the broker has verified the successful delivery of those messages to all clients and downstream event brokers.
Direct messages are delivered to subscribing clients in the order in which producers publish them. They are not spooled to non-volatile storage, and do not require acknowledgment.