Component: MQTT Client ( Comms)

Author	MatrixTSL
Version	0.1
Category	Comms

MQTT Client component

A component providing access to MQTT IoT client. The client can connect to a MQTT server such as ThingSpeak via WebSockets. Allows IoT type data to be published and read back.

Component Source Code

Please click here to download the component source project: FC_Comp_Source_WEBEXP_MQTT.fcsx

Please click here to view the component source code (Beta): FC_Comp_Source_WEBEXP_MQTT.fcsx

Detailed description

Please note this component currently only supports Web Sockets and must be connected to the Web Socket enabled port of the broker.

Examples

Temperature and Humidity

Here is an example MQTT project showing how to collect data from a remote device using MQTT.

The heater and fan buttons have onclick event macros that encode JSON data and send to a MQTT topic named mtx_demo_switchdata.

The OnMqttConnected event macro subscribes to MQTT topics named mtx_demo_sensedata which contains the embdeeded temperature and humidity data and mtx_demo_switchdata which contains the current fan and heater output states.

MQTT Web App Client Demo

Here is a corresponding ESP32 project that samples a temperature and humidity sensor and sends the data.

MQTT ESP32 Client Demo

Temperature and Humidity HTTPS

Here is the temperature and humidity example again but this time set to use HTTPS so that it can be ran from a enabled HTTPS webserver.

MQTT Web App Client HTTPS Demo

An example of this can be seen via the URL: https://flowcode.co.uk/example/index.htm

Macro reference

Connect

	Connect
Connects to the MQTT server (returns false if already connected)
- BOOL	Return

Disconnect

	Disconnect
Disconnect from the MQTT server (returns false if client is already disconnected)
- BOOL	Return

GetClientId

	GetClientId
Returns the unique identifier currently used when communicating with the server.
- STRING	Return

Publish

	Publish
Publish a message to the MQTT server (returns false in the client is not connected)
- STRING	Topic
The name of the topic for the message
- STRING	Message
The message to publish
- BYTE	QoS
The quality of service used to deliver the message (0, 1 or 2)
- BOOL	Retained
If true. the message is to be retained by the server and delivered to future subscribers as well as current ones
- BOOL	Return

PublishBuffer

	PublishBuffer
Publish an array of bytes to the MQTT server (returns false in the client is not connected)
- STRING	Topic
The name of the topic for the message
- HANDLE	Buffer
The message to publish (as an array buffer)
- BYTE	QoS
The quality of service used to deliver the message (0, 1 or 2)
- BOOL	Retained
If true. the message is to be retained by the server and delivered to future subscribers as well as current ones
- BOOL	Return

Subscribe

	Subscribe
Subscribe to messages from the MQTT server (returns false in the client is not connected)
- STRING	Topic
A filter for the topic name(s) to receive
- BYTE	QoS
The quality of service used to deliver the message (0, 1 or 2)
- BYTE	Timeout
The number of seconds to wait before assuming this operation failed
- BOOL	Return

Unsubscribe

	Unsubscribe
Unsubscribe from messages from the MQTT server (returns false in the client is not connected)
- STRING	Topic
A filter for the topic name(s) to stop receiving
- BYTE	Timeout
The number of seconds to wait before assuming this operation failed
- BOOL	Return

Property reference

	Properties
	Host
The address of the messaging server, as a fully qualified WebSocket URI, as a DNS name or dotted decimal IP address
	Port
The port number to connect to
	Directory
An optional subdirectory off the host address (e.g. "/mqtt")
	Client Id
A unique identifier for this client, between 1 and 23 characters in length
	Advanced
	Use SSL
Use a secure (SSL) connection
	Use authentication
Use authentication
	Connection timeout
If connection has not succeeded within this time (in seconds), it is deemed to have failed
	Keep Alive Interval
The server will disconnect this client if there is no activity for this time period (in seconds)
	Clean Session
If true, a non-persistent connection is created, meaning subscription information and undelivered messages are not retained when this connection ends
	Reconnect
If true, this client will attempt to reconnect to the server if the connection is lost
	Send LWT
Send a 'Last Will and Testament' message if unexpected disconnection occurs
	MQTT Version
Which version of MQTT to use
	Debug
Determines if additional logging information is sent to the JavaScript console
	Callbacks
	OnSuccess
Called when an MQTT operation is successful
	OnFailure
Called when an MQTT operation is unsuccessful
	OnConnected
Called when an MQTT connection is successfully made to the server
	OnConnectionLost
Called when an MQTT connection has been lost
	OnMessageDelivered
Called when an MQTT message has been delivered
	OnMessageArrived
Called when an MQTT message has arrived at this client