TsgcWSPClient_MQTT | MQTT Publish Subscribe

The publish/subscribe pattern (also known as pub/sub) provides an alternative to traditional client-server architecture. In the client-sever model, a client communicates directly with an endpoint.The pub/sub model decouples the client that sends a message (the publisher) from the client or clients that receive the messages (the subscribers). The publishers and subscribers never contact each other directly. In fact, they are not even aware that the other exists. The connection between them is handled by a third component (the broker). The job of the broker is to filter all incoming messages and distribute them correctly to subscribers.

 

With TsgcWSPClient_MQTT you can Publish messages and Subscribe to Topics.

 

Subscribe Topic

Subscribe to Topic "topic1" after a successful connection.

oClient := TsgcWebSocketClient.Create(nil);
oClient.Host := 'test.mosquitto.org';
oClient.Port := 8080;
oMQTT := TsgcWSPClient_MQTT.Create(nil);
oMQTT.Client := oClient;
oClient.Active := True;
 
procedure OnMQTTConnect(Connection: TsgcWSConnection; const Session: Boolean; const ReasonCode: Integer; 
  const ReasonName: string; const ConnectProperties: TsgcWSMQTTCONNACKProperties);
begin
  oMQTT.Subscribe('topic1');
end;

Publish Message

Publish a message to all subscribers of "topic1"

 

oClient := TsgcWebSocketClient.Create(nil);
oClient.Host := 'test.mosquitto.org';
oClient.Port := 8080;
oMQTT := TsgcWSPClient_MQTT.Create(nil);
oMQTT.Client := oClient;
oClient.Active := True;
 
procedure OnMQTTConnect(Connection: TsgcWSConnection; const Session: Boolean; const ReasonCode: Integer; 
  const ReasonName: string; const ConnectProperties: TsgcWSMQTTCONNACKProperties);
begin
  oMQTT.Publish('topic1', 'Hello Subscribers topic1');
end;