IOT-MQTT protocol - Control packets -PUBLISHCOMP

3.7 PUBCOMP - complete release (release received QoS 2, Part 3)

PUBCOMP PUBREL packet is a response packet. It is a protocol for exchanging QoS 2 fourth and last data packet.

3.7.1 Fixed Header fixed title

FIG 3.18 - PUBCOMP fixed packet header

Place	7	6	5	4	3	2	1	0
Byte 1	MQTT control packet type (7)				reserved
	0	1	1	1	0	0	0	0
Byte 2	The remaining length (2)
	0	0	0	0	0	0	1	0

The remaining length field

This is a variable length header. For PUBCOMP packet, a value of 2.

3.7.2 Variable header variable head

PUBREL variable header contains the same packets of the packet identifier being acknowledged.

FIG 3.19 - PUBCOMP Packet header variables

Place	7	6	5	4	3	2	1	0
Byte 1	MSB packet identifier
Byte 2	LSB packet identifier

 

3.7.3 Payload Payload

PUBCOMP packet no load.

3.7.4 Actions Action

This is described in detail in Section 4.3.3.

Question: mqtt qos1 qos2 and execution of subsequent chapters will draw a timing diagram corresponding! 20,190,624