The
mqttSession type is used to define the parameters for connecting to the MQTT broker. These connection parameters can be defined and changed by several WLanguage properties.
Remark: For more details on the declaration of this type of variable and the use of WLanguage properties, see
Declaring a variable.
// Declare the MQTT connection
gMqttSession is mqttSession
// Retrieve the data typed in the connection window
gMqttSession.Address = EDT_Broker_Address
gMqttSession.Port = EDT_Port
gMqttSession.Option = CBOX_SSL
gMqttSession.ConnectionTimeout = EDT_Connection_Timeout
gMqttSession.User = EDT_Login
gMqttSession.UserPassword = EDT_PSW
gMqttSession.PrivateKey = EDT_Private_Key
gMqttSession.PrivateKeyPassword = EDT_Private_Key_PSW
gMqttSession.ClientID = EDT_ClientID
gMqttSession.CleanSession = CBOX_Clean_Session
IF MQTTConnect(gMqttSession) THEN
Message("Connection OK")
ELSE
Error("Connection problem. '" + ErrorInfo() + "')")
END
Remarks
Properties specific to mqttSession variables
The following properties can be used to handle a MQTT session:
| | |
| Property name | Type used | Effect |
|---|
| Address | Character string | Address of MQTT server (also called "MQTT broker"). This address can be given in the following format:- IP address in XXX.XXX.XXX.XXX format (125.5.110.100 for example).
- IP address containing the server name (MQTTServer for example). This syntax is recommended.
|
| CleanSession | Boolean | - True to clean the generic global parameters on the server,
- False otherwise.
|
| ClientID | Character string | Client identifier. This property must not be left empty. |
| ConnectionTimeout | Integer ou Duration | Connection timeout in seconds. This property can correspond to: - an integer corresponding to the number of seconds,
- a Duration variable,
- the duration in a readable format (e.g., 10 s).
|
| Option | Integer constant | Connection options. This property can correspond to the optionSSL constant for an SSL connection. |
| Port | Integer | Port of MQTT server. This port correspondsn to 1883 by default (or 8883 for an SSL connection). |
| PrivateKey | Character string or Certificate variable | Name of the Certificate variable or path of the pem file (to make a private key connection). If this property is specified, an authentication by key is performed: only the User, PrivateKey and PrivateKeyPassword properties are taken into account. |
| PrivateKeyPassword | Character string | Password of key file (for a connection by private key). The PrivateKey property corresponds to the private key to be used. |
| User | Character string | Username. |
| UserPassword | Character string | User's password used in password authentication (the User property is the user's name). |
Authentication mode
The authentication by key has priority over the authentication by password.
Key authentication is used if:
- the server supports this authentication mode.
- the PrivateKey property is specified.
Password authentication is used if:
- the server supports this authentication mode.
- the UserPassword is specified.
Functions that use mqttSession variables
The following functions are used to handle the
mqttSession variables: