Connect Method

Connects to the remote host.

procedure Connect(Host: String; Port: Integer);

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 component 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 component sends the following information:

• The values of the ClientId, CleanSession, and KeepAliveInterval properties.
• The value of the User property (if non-empty).
• The value of the Password property (if non-empty).
• The values of the WillTopic and WillMessage properties and the WillQOS and WillRetain configuration settings.
• MQTT 5 specific values from ClientTopicAliasMax, SessionExpInterval, ConnectProperties and WillProperties.

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