Paho Asynchronous MQTT C Client Library
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#include <MQTTAsync.h>
Data Fields | |
char | struct_id [4] |
int | struct_version |
int | payloadlen |
void * | payload |
int | qos |
int | retained |
int | dup |
int | msgid |
MQTTProperties | properties |
A structure representing the payload and attributes of an MQTT message. The message topic is not part of this structure (see MQTTAsync_publishMessage(), MQTTAsync_publish(), MQTTAsync_receive(), MQTTAsync_freeMessage() and MQTTAsync_messageArrived()).
char struct_id[4] |
The eyecatcher for this structure. must be MQTM.
int struct_version |
The version number of this structure. Must be 0 or 1. 0 indicates no message properties
int payloadlen |
The length of the MQTT message payload in bytes.
void* payload |
A pointer to the payload of the MQTT message.
int qos |
The quality of service (QoS) assigned to the message. There are three levels of QoS:
int retained |
The retained flag serves two purposes depending on whether the message it is associated with is being published or received.
retained = true
For messages being published, a true setting indicates that the MQTT server should retain a copy of the message. The message will then be transmitted to new subscribers to a topic that matches the message topic. For subscribers registering a new subscription, the flag being true indicates that the received message is not a new one, but one that has been retained by the MQTT server.
retained = false
For publishers, this indicates that this message should not be retained by the MQTT server. For subscribers, a false setting indicates this is a normal message, received as a result of it being published to the server.
int dup |
The dup flag indicates whether or not this message is a duplicate. It is only meaningful when receiving QoS1 messages. When true, the client application should take appropriate action to deal with the duplicate message.
int msgid |
The message identifier is normally reserved for internal use by the MQTT client and server.
MQTTProperties properties |
The MQTT V5 properties associated with the message.