MQTT Native API

Extensions

Functions

int	mqttConnect(Mqtt mq, cchar username, cchar *password, int flags, MqttWaitFlags waitFlags)
	Establish a session with the MQTT broker.
cchar*	mqttGetError(struct Mqtt *mq)
	Returns an error message for error code, error
int	mqttMsgsInQueue(Mqtt *mq)
	Get the number of messages to send in the send queue.
int	mqttMsgsToSend(Mqtt *mq)
	Get the number of messages in the queue.
int	mqttPing(Mqtt *mq)
	Ping the broker.
int	mqttPublish(Mqtt mq, cvoid msg, ssize size, int qos, MqttWaitFlags waitFlags, cchar *topic, ...)
	Publish an application message to the MQTT broker.
int	mqttPublishRetained(Mqtt mq, cvoid msg, ssize size, int qos, MqttWaitFlags waitFlags, cchar *topic, ...)
	Publish a retained message to the MQTT broker.
void	mqttSetMessageSize(Mqtt *mq, int size)
	Set the maximum message size.
int	mqttSubscribe(Mqtt mq, MqttCallback callback, int maxQos, MqttWaitFlags waitFlags, cchar topic, ...)
	Subscribe to a topic.
int	mqttUnsubscribe(Mqtt mq, cchar topic, MqttWaitFlags wait)
	Unsubscribe from a topic.

Typedefs

Mqtt	An MQTT mq.
MqttCallback	Subscription callback.
MqttHdr	Fixed header of a packet.
MqttResp	A struct used to deserialize/interpret an incoming packet from the broker.
MqttRespConn	A connection response.
MqttRespPing	The resp to a ping request.
MqttRespPub	A publish packet received from the broker.
MqttRespPubAck	A publish acknowledgement for messages that were published with QoS level 1.
MqttRespPubComp	The resp to a PUBREL packet.
MqttRespPubRec	The resp packet to a PUBLISH packet with QoS level 2.
MqttRespPubRel	The resp to a PUBREC packet.
MqttRespSubAck	The resp to a subscription request.
MqttRespUnsubAck	The brokers resp to a UNSUBSCRIBE request.

Defines

#define	MQTT_PROTOCOL_LEVEL 0x04
	Protocol version.

Functions

int mqttConnect (Mqtt *mq, cchar *username, cchar *password, int flags, MqttWaitFlags waitFlags)

Establish a session with the MQTT broker.

: Mqtt_init must have been called.

Parameters:

mq	The Mqtt object.
username	The username to use when establishing the session with the MQTT broker. Set to NULL if a username is not required.
password	The password to use when establishing the session with the MQTT broker. Set to NULL if a password is not required.
flags	Additional MqttConnectFlags to use when establishing the connection. These flags are for forcing the session to start clean, MQTT_CONNECT_CLEAN_SESSION, the QOS level to publish the will_message with (provided will_message != NULL), MQTT_CONNECT_WILL_QOS_[0,1,2], and whether or not the broker should retain the will_message, MQTT_CONNECT_WILL_RETAIN.
waitFlags	Wait flags.

Returns:: Zero if successful.

API Stability:: Evolving.

cchar * mqttGetError (struct Mqtt *mq)

Returns an error message for error code, error

Parameters:

mq	Mqtt object.

Returns:: The associated error message.

API Stability:: Evolving.

int mqttMsgsInQueue (Mqtt *mq)

Get the number of messages to send in the send queue.

Parameters:

mq	The MQTT mq.

Returns:: The number of messages in the queue to send.

API Stability:: Evolving.

int mqttMsgsToSend (Mqtt *mq)

Get the number of messages in the queue.

Parameters:

mq	The MQTT mq.

Returns:: The number of messages in the queue.

API Stability:: Evolving.

int mqttPing (Mqtt *mq)

Ping the broker.

: MqttConnect must have been called.

Parameters:

mq	The MQTT mq.

Returns:: Zero if successful.

API Stability:: Evolving.

int mqttPublish (Mqtt *mq, cvoid *msg, ssize size, int qos, MqttWaitFlags waitFlags, cchar *topic, ...)

Publish an application message to the MQTT broker.

: MqttConnect must have been called.

Parameters:

mq	The Mqtt object.
msg	The data to be published.
size	The size of application_message in bytes.
qos	Quality of service. 0, 1, or 2.
waitFlags	Wait flags.
topic	Printf style topic string.
...	Topic args.

Returns:: Zero if successful.

int mqttPublishRetained (Mqtt *mq, cvoid *msg, ssize size, int qos, MqttWaitFlags waitFlags, cchar *topic, ...)

Publish a retained message to the MQTT broker.

: MqttConnect must have been called.

Parameters:

mq	The Mqtt object.
msg	The data to be published.
size	The size of application_message in bytes.
qos	Quality of service. 0, 1, or 2.
waitFlags	Wait flags.
topic	Printf style topic string.
...	Topic args.

Returns:: Zero if successful.

void mqttSetMessageSize (Mqtt *mq, int size)

Set the maximum message size.

Description:: AWS supports a smaller maximum message size.

Parameters:

mq	The MQTT mq.
size	The maximum message size.

API Stability:: Evolving.

int mqttSubscribe (Mqtt *mq, MqttCallback callback, int maxQos, MqttWaitFlags waitFlags, cchar *topic, ...)

Subscribe to a topic.

: MqttConnect must have been called.

Parameters:

mq	Mqtt object.
callback	Function to invoke on receipt of messages.
maxQos	Maximum quality of service message to receive.
waitFlags	Wait flags.
topic	Printf style topic string.
...	Topic args.

Returns:: Zero if successful.

API Stability:: Evolving.

int mqttUnsubscribe (Mqtt *mq, cchar *topic, MqttWaitFlags wait)

Unsubscribe from a topic.

: MqttConnect must have been called.

Parameters:

mq	The MQTT mq.
topic	The name of the topic to unsubscribe from.
wait	Wait flags.

Returns:: Zero if successful.

API Stability:: Evolving.

Typedefs

typedef void(* MqttCallback) (struct MqttRespPub *resp).

Subscription callback.

Parameters:

resp	Message received structure.

API Stability:: Evolving.

Mqtt

An MQTT mq.

: All members can be manipulated via the related functions.

Fields:

API Stability:: Evolving.

MqttHdr

Fixed header of a packet.

API Stability:: Evolving.

Fields:

int		flags	Packet control flags.
int		length	Size in bytes.

MqttResp

A struct used to deserialize/interpret an incoming packet from the broker.

API Stability:: Evolving.

Fields:

MqttRespConn

A connection response.

API Stability:: Evolving.

Fields:

MqttConnCode		code	Connection return code.
uchar		hasSession	Check if already have a session.

MqttRespPing

The resp to a ping request.

: This resp contains no members.

Fields:

API Stability:: Evolving.

MqttRespPub

A publish packet received from the broker.

Description:: A publish packet is received from the broker when a mq publishes to a topic that the {local mq} is subscribed to.

Fields:

cvoid *	data	Message.
int	dataSize	Size of message.
MqttCallback	callback	Message callback function.
uchar	dup	Set to 0 on first attempt to send packet.
char *	fullTopic	Full topic string.
uint16_t	id	Message ID.
struct Mqtt *	mq	Message queue.
uchar	qos	Quality of service.
uchar	retain	Message is retained.
cvoid *	topic	Topic string. Not null terminated.
uint16_t	topicSize	Size of the topic.

API Stability:: Evolving.

MqttRespPubAck

A publish acknowledgement for messages that were published with QoS level 1.

API Stability:: Evolving.

Fields:

uint16_t

Message ID.

MqttRespPubComp

The resp to a PUBREL packet.

API Stability:: Evolving.

Fields:

uint16_t

Message ID.

MqttRespPubRec

The resp packet to a PUBLISH packet with QoS level 2.

API Stability:: Evolving.

Fields:

uint16_t

Message ID.

MqttRespPubRel

The resp to a PUBREC packet.

API Stability:: Evolving.

Fields:

uint16_t

Message ID.

MqttRespSubAck

The resp to a subscription request.

API Stability:: Evolving.

Fields:

cuchar *	codes	Array of return codes for subscribed topics.
uint16_t	id	Message ID.
int	numCodes	Size of codes.

MqttRespUnsubAck

The brokers resp to a UNSUBSCRIBE request.

API Stability:: Evolving.

Fields:

uint16_t

Message ID.