• Number of published message (mqttQualityExactlyOnce and mqttQualityAtLeastOnce constants).
• 0 if the publication is successful (mqttQualityAtMostOnce constant).
• -1 if an error occurred.

Name of the mqttSession variable corresponding to the MQTT session to be used.

Message topic.

Data to publish (must not exceed 256MB).

• True if the message must be stored on the server.
• False (by default) otherwise.

Requested service quality:

mqttQualityAtLeastOnce	The message will be delivered at least once. The client will transmit the message several times if necessary until the server (broker) confirms that the message was transmitted on the network. Equivalent to QOS set to 1.
mqttQualityAtMostOnce	The message will be delivered once at most. The message is not stored. It is sent without guarantee of receipt. The MQTT (broker) does not inform the sender that the message was received. The message can be lost if the client is disconnected or if the server is stopped. Equivalent to QOS set to 0.
mqttQualityExactlyOnce	The message will be necessarily saved by the issuer. It will be transmitted as long as the receiver does not confirm its sending on the network. The issuer is using a sophisticated recognition with the server (broker) to avoid duplicating messages. This mode is slower but it is more secure. Equivalent to QOS set to 2.

Name of WLanguage procedure ("callback") run when the message was published (this procedure is called if the mqttQualityExactlyOnce and mqttQualityAtLeastOnce constants are used). This procedure has the following format:

PROCEDURE <Procedure name>(<Session> is mqttSession,
<Message num> is int)

where:

• <Session> corresponds to a mqttSession variable containing the characteristics of MQTT session.
• <Message num> corresponds to the number of published message.