With The Clear Session Flag Set To False, I Am Missing The Published Values

Is anyone has a logical explanation why despite I have the clear session flage = false I do not receive the updated published message I am subscribed to while i am not connected to

Solution 1:

In order for messages to be queued for a client that is no longer connected to a broker, these things must be true:

• Client must have originally connected with clean session set to false
• Client must have subscribed with QoS>0
• Messages to that topic must have been published with QoS>0
• When the client reconnects it must have the same client id as when it disconnected
• When the client reconnects it must have clean session set to false

My bet is that you are failing on either of the latter two points.

Solution 2:

You need to send the messages with the retain flag to be able to recieve the messages when you re-connect. The QoS defines how hard the broker/client will try to ensure that a message is received.

Have a read here http://mosquitto.org/man/mqtt-7.html on QOS, clean session and retained messages.