MQTT qos1 & qos2

[Siva Nallamalli]

For publishing MQTT Messages(QoS1 & QoS2) to the brocker, is it neccesary to enable/use persistant option on client?

If no,  does the existing MQTT client will hold the existing messages untill it get PUBACK/PUBREL mesages from brocket.

[Siva Nallamalli]

On Tuesday, July 31, 2018 at 6:29:58 PM UTC+5:30, Siva Nallamalli wrote:

For publishing MQTT Messages(QoS1 & QoS2) to the brocker, is it neccesary to enable/use persistant option on client?

If no,  does the existing MQTT client will implicitly hold the existing messages untill it get PUBACK/PUBREL mesages from brocker. Is there any extra options need to enable with MQTT client?

 

 

[saurabh singh]

https://www.hivemq.com/blog/mqtt-essentials-part-6-mqtt-quality-of-service-levels

May be it will help you.

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[Sombaran Gupta]

Hi Siva,

When we are using QoS-->0 there is no acknowledgment of our messages but when we are using QoS----> 1/2 we get acknowledgement of every messages however the message and acknowledgement flow varies in both QOS---> 1/2, when is comes to broker

for client connection it can request a persistent session which means, when the clean session flag is set to true, the client does not want a persistent session i.e broker does not stores/saves any of the messages in the location (var/lib/mosquitto/mosquitto.db)

whereas When the clean session flag is set to false, the client wants a persistent session i.e broker stores/saves all of the messages in the location (var/lib/mosquitto/mosquitto.db)

There is client persistent session where client expiration period is configured

 persistent_client_expiration 2m
 persistent_client_expiration 14d
 persistent_client_expiration 1y

I hope this  will clear all your doubts

Regards

Sombaran Gupta

+91-9080391646

www.smartron.com