Connect Method

Connects to the remote host.

Syntax

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

Remarks

This method connects to the remote host. Calling this method is equivalent to setting the RemoteHost property to Host, setting RemotePort to Port, and then setting the Connected property to True.

By default the class will connect in plaintext. To enable SSL set SSLEnabled to True.

In addition, WebSocket connections are supported. To connect using WebSockets specify a hostname beginning with ws:// (plaintext) or wss:// (SSL). For instance, ws://test.mosquitto.org.

When connecting to an MQTT server, the class sends the following information:

If CleanSession is True, check the SessionPresent configuration setting once connected to determine whether the server actually had any session state saved.

Refer to CleanSession, SaveSession, and RestoreSession for more information about MQTT sessions and session state persistence; refer to WillTopic, WillMessage, WillQOS, and WillRetain for more information about MQTT Wills.

Basic Connection Example

mqtt1.ClientId = "testClient";
mqtt1.CleanSession = true;
mqtt1.KeepAliveInterval = 30;
mqtt1.WillTopic = "wills/" + mqtt1.ClientId;
mqtt1.WillMessage = mqtt1.ClientId + " was disconnected ungracefully!";
mqtt1.Connect("mqtt.test-server.com", 1883);

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 MQ 2020 Qt Edition - Version 20.0 [Build 8162]