Connect Method

Connects to the MQTTSN Gateway.

Syntax

int Connect(const QString& qsHost, int iPort);

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:

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);

Error Handling

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

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IPWorks IoT 2020 Qt Edition - Version 20.0 [Build 8265]