Networking Acronyms & Terminology
MO: Mobile originated. A message sent by a mobile or remote device, e.g. a phone, is MO.
MT: Mobile terminated. A message sent to a mobile or remote device, e.g. a backend server or provider, is MT.
TTL: Time-to-live. A message that has been in a queue for longer than the configured TTL is said to be dead, or expired.
MQTT: Message Queuing Telemetry Transport. A lightweight pub-sub network protocol. Ref: https://mqtt.org/
AMQP: Advanced Message Queuing Protocol. A powerful and flexible messaging queue protocol. See Setting up an AMQP Broker (RabbitMQ)
Durability is a property of (AMQP) broker entities; queues and exchanges. If the server restarts, a durable entity will be recreated.
Persistence is a property of messages. Persistence is usually handled by writes to disk in a persistency log. If the server restarts, any durable queues/exchanges will be re-populated with persistent messages.
- Read RabbitMQ - Persistency vs Durability for a great summary.
Hint
Message persistency, like everything else in life, comes at a price. Disk I/O is slow, and writing every message to disk can reduce the number of messages a broker can process per second.