Connect Method
Connects to the MQTTSN Gateway.
Syntax
mqttsn.connect(host, port, [callback])
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 this 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 method connects to the MQTTSN Gateway by sending a CONNECT packet. Calling this method is equivalent to setting the RemoteHost property to Host, setting RemotePort to Port, and then setting the Connected property to True.
When connecting to an MQTT gateway, the class sends the following information:
- The values of the ClientId, CleanSession, and KeepAliveInterval properties.
- The values of the WillTopic and WillMessage properties and the WillRetain and WillQOS configuration settings.
Refer to CleanSession for more information about MQTT sessions; refer to WillTopic, WillMessage, WillQOS and WillRetain for more information about MQTT Wills.
Basic Connection Example
mqttsn1.ClientId = "testClient";
mqttsn1.CleanSession = true;
mqttsn1.KeepAliveInterval = 30;
mqttsn1.WillTopic = "wills/" + mqttsn1.ClientId;
mqttsn1.WillMessage = mqttsn1.ClientId + " was disconnected ungracefully!";
mqttsn1.Connect(host, port);