MQTT by name is a misnomer. There are no message queues inherent in the protocol. While it is possible to queue messages, it's not necessary and often not done. MQTT is TCP based, and therefore includes some guarantee that a packet is transferred reliably.
MQTT is also an asymmetric protocol, whereas HTTP is a nonsymmetric protocol. Say node A needs to communicate with node B. An asymmetric protocol between A and B would only require one side (A) to use the protocol, however, all information needed for the reassembly of packets must be contained in the fragmentation header sent by A. Asymmetric systems have one master and one slave (FTP being a classic example). In a symmetric protocol, both A and B would have ...
