android - My messages are getting downgraded by MQTT-broker, so what? -

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as far understand, if subscribed topic specific qos, subscriber see messages under topic provided mqtt broker qos level equal or lower qos specified @ publishing topic.

in other words,the client subscribe, exampe, thetopic = news , qos = 1, able see published messages under topic = news withqos = 1 or 0

i subscribed topic = news qos = 0, topic published qos = 2, when connected broker, received te published message qos = 0, , second time, published same topic qos = 1, , when subscribed qos = 0, received message qos = 0.

so, since whatever qos level receive message but, qos "downgraded", what?what risk? can explain?!!

when make subscription saying broker "the maximum qos wish receive messages @ x". means if message comes in on topic subscribed @ higher qos, downgraded you. other clients not affected. table below clears you.

subscription qos | message qos | delivered qos =================|=============|==============        0         |       0     |       0        0         |       1     |       0        0         |       2     |       0                  |             |        1         |       0     |       0        1         |       1     |       1        1         |       2     |       1                  |             |        2         |       0     |       0        2         |       1     |       1        2         |       2     |       2

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