File Information
Library: IoT/MQTT
Package: MQTTClient
Header: IoT/MQTT/Types.h
Description
This structure encapsulates a MQTT message.
Constructors
Message 
Message();
Message
explicit Message(
int q
);
Message
Message(
const std::string & p,
int q
);
Message
Message(
const std::vector < char > & p,
int q
);
Message
Message(
std::string && p,
int q
);
Message
Message(
std::vector < char > && p,
int q
);
Variables
binaryPayload
std::vector < char > binaryPayload;
Alternative binary payload, considered if payload is empty.
payload
std::string payload;
The payload of the MQTT message.
properties
std::vector < Property > properties;
The MQTT V5 properties associated with this message.
qos
int qos = 0;
The quality of service (QoS) assigned to the message. There are three levels of QoS:
- 0: Fire and forget - the message may not be delivered.
- 1: At least once - the message will be delivered, but may be delivered more than once in some circumstances.
- 2: Once and one only - the message will be delivered exactly once.
retained
bool retained = false;
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.