Francois Normandin

If the Server receives a QoS 0 message with the RETAIN flag set to 1 it MUST discard any message previously retained for that topic. It SHOULD store the new...

When a new subscription is established, the last retained message, if any, on each matching topic name MUST be sent to the subscriber.

If the RETAIN flag is set to 1, in a PUBLISH Packet sent by a Client to a Server, the Server MUST store the Application Message and its QoS, so...

A PUBLISH Packet MUST NOT have both QoS bits set to 1. If a Server or Client receives a PUBLISH Packet which has both QoS bits set to 1 it...

The value of the DUP flag from an incoming PUBLISH packet is not propagated when the PUBLISH Packet is sent to subscribers by the Server. The DUP flag in the...

The DUP flag MUST be set to 0 for all QoS 0 messages.

The DUP flag MUST be set to 1 by the Client or Server when it attempts to re-deliver a PUBLISH Packet.

If none of the return codes listed in Table 3.1 – Connect Return code values are deemed applicable, then the Server MUST close the Network Connection without sending a CONNACK.

If a server sends a CONNACK packet containing a non-zero return code it MUST then close the Network Connection.

If the Server does not have stored Session state, it MUST set Session Present to 0 in the CONNACK packet. This is in addition to setting a zero return code...