!7

lib 1400324 // Eclipse Paho (MQTT)

import org.eclipse.paho.client.mqttv3.*;

cmodule MQTTSpike > DynPrintLog {
  switchable S topic = "iot_data";
  S messageText;
  transient MqttClient client;
  
  visual centerAndSouthWithMargins(super,
    dm_textFieldAndSubmit messageText('sendMessage, buttonText := "Send message"));
  
  start-thread {
    client = new MqttClient("tcp://localhost:1883", MqttClient.generateClientId());
    client.setCallback(new MyCallback);
    client.connect();
    client.subscribe(topic);
    print("Connected & subscribed to " + topic);
  }
  
  void cleanMeUp_mqtt ctex {
    if (client != null) {
      client.disconnect();
      client.close();
    }
  }
  
  class MyCallback implements MqttCallback {
    public void connectionLost(Throwable throwable) enter {
      print("Connection to MQTT broker lost!");
    }

    public void messageArrived(S s, MqttMessage mqttMessage) enter {
      print("Message received: "+ fromUtf8(mqttMessage.getPayload()));
    }

    public void deliveryComplete(IMqttDeliveryToken token) enter {
      print("Delivery complete: " + token);
    }
  }
  
  void sendMessage ctex {
    temp enter();
    new MqttMessage message;
    message.setPayload(toUtf8(messageText));
    client.publish(topic, message);
    print("Published message: " + messageText);
  }
  
  // API
  
  void sendMessage(S topic, S text) ctex {
    new MqttMessage message;
    message.setPayload(toUtf8(text));
    client.publish(topic, message);
    print("Published message in " + topic + ": " + text);
  }
}

Began life as a copy of #1026859