MQTT FSM
		
		
		
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MQTT Handshaking - A FSM (Finite State Machine) of the Protocol
Not proofread!
QoS 0
| Device | Broker | 
|---|---|
| Establishes TCP connection to broker | |
| CONNECT -> | |
| <- CONNACK | |
| PUBLISH -> | |
| SUBSCRIBE -> | |
| <- PUBLISH | |
| UNSUBSCRIBE -> | |
| DISCONNECT -> | |
| Closes TCP connection to device | 
QoS 1
| Device | Broker | 
|---|---|
| Establishes TCP connection to broker | |
| CONNECT -> | |
| <- CONNACK | |
| PUBLISH -> | |
| <- PUBACK | |
| SUBSCRIBE -> | |
| <- SUBACK | |
| <- PUBLISH | |
| PUBACK -> | |
| UNSUBSCRIBE -> | |
| <- UNSUBACK | |
| DISCONNECT -> | |
| Closes TCP connection to device | 
QoS 2
TBD
| Device | Broker | 
|---|---|
| Establishes TCP connection to broker | |
| CONNECT -> | |
| <- CONNACK | |
| PUBLISH -> | |
| <- PUBREC | |
| PUBCOMP -> | |
| <- PUBREL | |
| SUBSCRIBE -> | |
| <- PUBLISH | |
| UNSUBSCRIBE -> | |
| DISCONNECT -> | |
| Closes TCP connection to device |