Create MQTT client connected to broker
Since R2022a
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Description
An icomm.mqtt.Client object represents an MQTT client in MATLAB® that connects to an external MQTT broker.
Creation
Syntax
mqttClient = mqttclient(brokerAddr)
mqttClient = mqttclient(brokerAddr,Name=Value)
Description
example
mqttClient = mqttclient(brokerAddr)brokerAddr. brokerAddr is a host name or IP address of the MQTT broker including the connection protocol. Supported protocols include MQTT, TCP, WS, SSL, and WSS.
mqttClient = mqttclient(brokerAddr,Name=Value)mqttClient using optional name-value pairs.
Input Arguments
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brokerAddr — Location of MQTT broker
string | char
Location of MQTT broker as a URL, including protocol, specified as a string or character vector.
Supported protocols are:
mqtt://tcp://ws://ssl://wss://
Example: "tcp://broker.hivemq.com"
Data Types: string | char
Name-Value Arguments
Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.
Example: Port=8883
Name-value arguments can specify the properties Port, ClientID, Timeout, and KeepAliveDuration; and the following options:
Username — User name for connection to broker
string | char
User name for connection to broker, specified as a string or character vector.
Data Types: char | string
Password — User password for connection to broker
string | char
User password for connection to broker, specified as a string or character vector.
Data Types: char | string
CARootCertificate — Server root certificate for broker authentication
string | char
Server root certificate for broker authentication during a secure connection, specified as a string or character vector.
Data Types: char | string
ClientCertificate — Certificate for client authentication
string | char
Certificate for client authentication during a secure connection, specified as a string or character vector.
Data Types: char | string
ClientKey — Private key file for client authentication
string | char
Private key file for client authentication, used along with ClientCertificate for authentication during secure connection.
Data Types: char | string
SSLPassword — Password to decrypt private key
string | char
Password to decrypt the private ClientKey file, specified as a string or character vector.
Data Types: char | string
Properties
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Port — Socket port number for connection
integer value
This property is read-only.
Socket port number to use when connecting to the MQTT broker, specified as an integer value.
Example: 8883
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical
ClientID — Identifier of client
string | char
This property is read-only.
Identifier of client for connection to broker, specified as a string or character vector.
Data Types: char | string
Timeout — Time allowed to complete connection
5 (default) | integer value | duration
This property is read-only.
Time allowed for connection to be completed, specified as a numeric integer value in seconds or as a duration.
Example: Timeout=60
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | duration
KeepAliveDuration — Maximum idle time allowed between broker and client
60 (default) | integer value | duration
This property is read-only.
Maximum idle time allowed between broker and client, specified as a numeric integer value in seconds or as a duration. If no traffic occurs in this time span, the client issues a keep alive packet.
Example: KeepAliveDuration=minutes(5)
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | duration
BrokerAddress — Location of MQTT broker
string | char
This property is read-only.
Location of the MQTT broker, specified as a string or character vector. BrokerAddress identifies the host name or IP address of the MQTT broker, including connection protocol. Supported protocols include TCP, WS, SSL, and WSS.
Example: "tcp://broker.hivemq.com"
Data Types: char | string
Subscriptions — Table of topic subscriptions
table
This property is read-only.
Table of topics client is subscribed to.
Data Types: table
Connected — Status of client connection to broker
1 | 0
This property is read-only.
Status of the client connection to the broker, returned as logical 1 (connected) or 0 (not connected). If the Connected status is 0, that might indicate an issue with the broker; check that you have the correct address, clear the object, and try creating it again.
Example: 1
Data Types: logical
Object Functions
| subscribe | Subscribe to MQTT topic |
| unsubscribe | Unsubscribe from MQTT topics |
| read | Read available messages from MQTT topic |
| peek | View most recent message from MQTT topic |
| flush | Clear received MQTT messages |
| write | Write message to MQTT topic |
Examples
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Connect to an MQTT Broker
Create a nonsecure MQTT client connection to a HiveMQ public broker with default settings.
mqttClient = mqttclient("tcp://broker.hivemq.com")mqttClient = Client with properties: BrokerAddress: "tcp://broker.hivemq.com" Port: 1883 ClientID: "" Timeout: 5 KeepAliveDuration: 60 Subscriptions: [0×3 table] Connected: 1
Connect with a Specific ID and Port
Create a nonsecure MQTT client connection to a HiveMQ public broker using port 1883 and specify the client ID as myClient.
mqttClient = mqttclient("tcp://broker.hivemq.com",ClientID="myClient",Port=1883)
mqttClient = Client with properties: BrokerAddress: "tcp://broker.hivemq.com" Port: 1883 ClientID: "myClient" Timeout: 5 KeepAliveDuration: 60 Subscriptions: [0×3 table] Connected: 1
Make a Secure Connection over SSL
Create an MQTT client with a secure connection over SSL using certificates for authentication. Connect the client to the Eclipse Mosquitto™ public broker at port 8884 and specify the broker root certificate, client certificate, and private key.
mqttClientSSL = mqttclient("ssl://mosquitto.org",Port=8884,... CARootCertificate="C:\mqtt\mosquitto.org.pem",... ClientCertificate="C:\mqtt\client.pem",... ClientKey="C:\mqtt\client.key")
Make a Connection over Websockets
Create an MQTT client connected with websockets to ThingSpeak™. Connecting with the MQTT interface on ThingSpeak requires ClientID, Username, and Password.
mqttClient = mqttclient("ws://mqtt3.thingspeak.com",Port=80,... Username="MyUserID",ClientID="MyClientID",Password="MyPassword")
Create a client with a secure connection.
mqttClient = mqttclient("wss://mqtt3.thingspeak.com",Port=443,... Username="MyUserID",ClientID="MyClientID",Password="MyPassword")
Version History
Introduced in R2022a
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R2023b: Support for MQTT Protocol
The mqttclient function is enhanced to support the mqtt:// protocol.
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