WillMessage Property

The message that the server should publish in the event of an ungraceful disconnection.

Syntax

 mqttsn.getWillMessage([callback])
 mqttsn.setWillMessage( willMessage, [callback])

Default Value

""

Callback

The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).

The callback for the getWillMessage([callback]) method is defined as:

function(err, data){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'data' is the value returned by the method.

The callback for the setWillMessage([callback]) method is defined as:

function(err){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'err' has 2 properties which hold detailed information:

err.code
err.message

Remarks

This property may be set before calling Connect to specify to the server a message that should be published on WillTopic if the connection is closed ungracefully or lost.

The WillMessage will only be sent to the server when Connect is called if WillTopic is set. Note that in MQTTSN the clean session concept is extended to will topic and will message. The WillMessage can be updated with the UpdateWillMessage method.

Refer to WillTopic for more information about MQTT Will functionality.

This property is not available at design time.

Data Type

String