Demonstrates usage of the MQTT library. More...

#include "iot_config.h"
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "iot_demo_logging.h"
#include "platform/iot_clock.h"
#include "platform/iot_threads.h"
#include "iot_mqtt.h"

Macros
#define	CLIENT_IDENTIFIER_PREFIX "iotdemo"
	The first characters in the client identifier. A timestamp is appended to this prefix to create a unique client identifer. More...

#define	CLIENT_IDENTIFIER_MAX_LENGTH ( 24 )
	The longest client identifier that an MQTT server must accept (as defined by the MQTT 3.1.1 spec) is 23 characters. Add 1 to include the length of the NULL terminator.

#define	KEEP_ALIVE_SECONDS ( 60 )
	The keep-alive interval used for this demo. More...

#define	MQTT_TIMEOUT_MS ( 5000 )
	The timeout for MQTT operations in this demo.

#define	WILL_TOPIC_NAME IOT_DEMO_MQTT_TOPIC_PREFIX "/will"
	The Last Will and Testament topic name in this demo. More...

#define	WILL_TOPIC_NAME_LENGTH ( ( uint16_t ) ( sizeof( WILL_TOPIC_NAME ) - 1 ) )
	The length of WILL_TOPIC_NAME.

#define	WILL_MESSAGE "MQTT demo unexpectedly disconnected."
	The message to publish to WILL_TOPIC_NAME.

#define	WILL_MESSAGE_LENGTH ( ( size_t ) ( sizeof( WILL_MESSAGE ) - 1 ) )
	The length of WILL_MESSAGE.

#define	TOPIC_FILTER_COUNT ( 4 )
	How many topic filters will be used in this demo.

#define	TOPIC_FILTER_LENGTH ( ( uint16_t ) ( sizeof( IOT_DEMO_MQTT_TOPIC_PREFIX "/topic/1" ) - 1 ) )
	The length of each topic filter. More...

#define	PUBLISH_PAYLOAD_FORMAT "Hello world %d!"
	Format string of the PUBLISH messages in this demo.

#define	PUBLISH_PAYLOAD_BUFFER_LENGTH ( sizeof( PUBLISH_PAYLOAD_FORMAT ) + 2 )
	Size of the buffer that holds the PUBLISH messages in this demo.

#define	PUBLISH_RETRY_LIMIT ( 10 )
	The maximum number of times each PUBLISH in this demo will be retried.

#define	PUBLISH_RETRY_MS ( 1000 )
	A PUBLISH message is retried if no response is received within this time.

#define	ACKNOWLEDGEMENT_TOPIC_NAME IOT_DEMO_MQTT_TOPIC_PREFIX "/acknowledgements"
	The topic name on which acknowledgement messages for incoming publishes should be published.

#define	ACKNOWLEDGEMENT_TOPIC_NAME_LENGTH ( ( uint16_t ) ( sizeof( ACKNOWLEDGEMENT_TOPIC_NAME ) - 1 ) )
	The length of ACKNOWLEDGEMENT_TOPIC_NAME.

#define	ACKNOWLEDGEMENT_MESSAGE_FORMAT "Client has received PUBLISH %.*s from server."
	Format string of PUBLISH acknowledgement messages in this demo.

#define	ACKNOWLEDGEMENT_MESSAGE_BUFFER_LENGTH ( sizeof( ACKNOWLEDGEMENT_MESSAGE_FORMAT ) + 2 )
	Size of the buffers that hold acknowledgement messages in this demo.

Functions
int	RunMqttDemo (bool awsIotMqttMode, const char pIdentifier, void pNetworkServerInfo, void pNetworkCredentialInfo, const IotNetworkInterface_t pNetworkInterface)
	The function that runs the MQTT demo, called by the demo runner. More...

static void	_operationCompleteCallback (void param1, IotMqttCallbackParam_t const pOperation)
	Called by the MQTT library when an operation completes. More...

static void	_mqttSubscriptionCallback (void param1, IotMqttCallbackParam_t const pPublish)
	Called by the MQTT library when an incoming PUBLISH message is received. More...

static int	_initializeDemo (void)
	Initialize the MQTT library. More...

static void	_cleanupDemo (void)
	Clean up the MQTT library.

static int	_establishMqttConnection (bool awsIotMqttMode, const char pIdentifier, void pNetworkServerInfo, void pNetworkCredentialInfo, const IotNetworkInterface_t pNetworkInterface, IotMqttConnection_t *pMqttConnection)
	Establish a new connection to the MQTT server. More...

static int	_modifySubscriptions (IotMqttConnection_t mqttConnection, IotMqttOperationType_t operation, const char *pTopicFilters, void pCallbackParameter)
	Add or remove subscriptions by either subscribing or unsubscribing. More...

static int	_publishAllMessages (IotMqttConnection_t mqttConnection, const char *pTopicNames, IotSemaphore_t pPublishReceivedCounter)
	Transmit all messages and wait for them to be received on topic filters. More...

Detailed Description

Demonstrates usage of the MQTT library.

Macro Definition Documentation

◆ CLIENT_IDENTIFIER_PREFIX

#define CLIENT_IDENTIFIER_PREFIX "iotdemo"

The first characters in the client identifier. A timestamp is appended to this prefix to create a unique client identifer.

This prefix is also used to generate topic names and topic filters used in this demo.

◆ KEEP_ALIVE_SECONDS

#define KEEP_ALIVE_SECONDS ( 60 )

The keep-alive interval used for this demo.

An MQTT ping request will be sent periodically at this interval.

◆ WILL_TOPIC_NAME

#define WILL_TOPIC_NAME IOT_DEMO_MQTT_TOPIC_PREFIX "/will"

The Last Will and Testament topic name in this demo.

The MQTT server will publish a message to this topic name if this client is unexpectedly disconnected.

◆ TOPIC_FILTER_LENGTH

#define TOPIC_FILTER_LENGTH ( ( uint16_t ) ( sizeof( IOT_DEMO_MQTT_TOPIC_PREFIX "/topic/1" ) - 1 ) )

The length of each topic filter.

For convenience, all topic filters are the same length.

Function Documentation

◆ RunMqttDemo()

int RunMqttDemo	(	bool	awsIotMqttMode,
		const char *	pIdentifier,
		void *	pNetworkServerInfo,
		void *	pNetworkCredentialInfo,
		const IotNetworkInterface_t *	pNetworkInterface
	)

The function that runs the MQTT demo, called by the demo runner.

Parameters

[in]	awsIotMqttMode	Specify if this demo is running with the AWS IoT MQTT server. Set this to `false` if using another MQTT server.
[in]	pIdentifier	NULL-terminated MQTT client identifier.
[in]	pNetworkServerInfo	Passed to the MQTT connect function when establishing the MQTT connection.
[in]	pNetworkCredentialInfo	Passed to the MQTT connect function when establishing the MQTT connection.
[in]	pNetworkInterface	The network interface to use for this demo.

Returns: EXIT_SUCCESS if the demo completes successfully; EXIT_FAILURE otherwise.

◆ _operationCompleteCallback()

static void _operationCompleteCallback	(	void *	param1,
		IotMqttCallbackParam_t *const	pOperation
	)

static

Called by the MQTT library when an operation completes.

The demo uses this callback to determine the result of PUBLISH operations.

Parameters

[in]	param1	The number of the PUBLISH that completed, passed as an intptr_t.
[in]	pOperation	Information about the completed operation passed by the MQTT library.

◆ _mqttSubscriptionCallback()

static void _mqttSubscriptionCallback	(	void *	param1,
		IotMqttCallbackParam_t *const	pPublish
	)

static

Called by the MQTT library when an incoming PUBLISH message is received.

The demo uses this callback to handle incoming PUBLISH messages. This callback prints the contents of an incoming message and publishes an acknowledgement to the MQTT server.

Parameters

[in]	param1	Counts the total number of received PUBLISH messages. This callback will increment this counter.
[in]	pPublish	Information about the incoming PUBLISH message passed by the MQTT library.

◆ _initializeDemo()

static int _initializeDemo ( void )

static

Initialize the MQTT library.

Returns: EXIT_SUCCESS if all libraries were successfully initialized; EXIT_FAILURE otherwise.

◆ _establishMqttConnection()

static int _establishMqttConnection	(	bool	awsIotMqttMode,
		const char *	pIdentifier,
		void *	pNetworkServerInfo,
		void *	pNetworkCredentialInfo,
		const IotNetworkInterface_t *	pNetworkInterface,
		IotMqttConnection_t *	pMqttConnection
	)

static

Establish a new connection to the MQTT server.

Parameters

[in]	awsIotMqttMode	Specify if this demo is running with the AWS IoT MQTT server. Set this to `false` if using another MQTT server.
[in]	pIdentifier	NULL-terminated MQTT client identifier.
[in]	pNetworkServerInfo	Passed to the MQTT connect function when establishing the MQTT connection.
[in]	pNetworkCredentialInfo	Passed to the MQTT connect function when establishing the MQTT connection.
[in]	pNetworkInterface	The network interface to use for this demo.
[out]	pMqttConnection	Set to the handle to the new MQTT connection.

Returns: EXIT_SUCCESS if the connection is successfully established; EXIT_FAILURE otherwise.

◆ _modifySubscriptions()

static int _modifySubscriptions	(	IotMqttConnection_t	mqttConnection,
		IotMqttOperationType_t	operation,
		const char **	pTopicFilters,
		void *	pCallbackParameter
	)

static

Add or remove subscriptions by either subscribing or unsubscribing.

Parameters

[in]	mqttConnection	The MQTT connection to use for subscriptions.
[in]	operation	Either IOT_MQTT_SUBSCRIBE or IOT_MQTT_UNSUBSCRIBE.
[in]	pTopicFilters	Array of topic filters for subscriptions.
[in]	pCallbackParameter	The parameter to pass to the subscription callback.

Returns: EXIT_SUCCESS if the subscription operation succeeded; EXIT_FAILURE otherwise.

◆ _publishAllMessages()

static int _publishAllMessages	(	IotMqttConnection_t	mqttConnection,
		const char **	pTopicNames,
		IotSemaphore_t *	pPublishReceivedCounter
	)

static

Transmit all messages and wait for them to be received on topic filters.

Parameters

[in]	mqttConnection	The MQTT connection to use for publishing.
[in]	pTopicNames	Array of topic names for publishing. These were previously subscribed to as topic filters.
[in]	pPublishReceivedCounter	Counts the number of messages received on topic filters.

Returns: EXIT_SUCCESS if all messages are published and received; EXIT_FAILURE otherwise.

Macros

Functions

Detailed Description

Macro Definition Documentation

◆ CLIENT_IDENTIFIER_PREFIX

◆ KEEP_ALIVE_SECONDS

◆ WILL_TOPIC_NAME

◆ TOPIC_FILTER_LENGTH

Function Documentation

◆ RunMqttDemo()

◆ _operationCompleteCallback()

◆ _mqttSubscriptionCallback()

◆ _initializeDemo()

◆ _establishMqttConnection()

◆ _modifySubscriptions()

◆ _publishAllMessages()