Lesson 14 Program implementation using Paho and ADT Example 9.12 in MQTT clients and MQTT broker communication with an Android phone

Transcription

1 Lesson 14 Program implementation using Paho and ADT Example 9.12 in MQTT clients and MQTT broker communication with an Android phone Chapter-9 L14: "Internet of Things ", Raj Kamal, 1

2 Program implementation in Pub/Sub mode Eclipse Paho programme implementation for communication with an Android phone using Paho and ADT Connected sensor and actuator, which are publishing the sensed data Subscribing for control messages using MQTT Android clients Coding is similar to Example

3 MQTT Client Implement codes for Subscriber class for subscribing to the sensed data for example, Electric Kettle Temperature Sensor by the Android phone Use Eclipse Moquette Paho implementation of MQTT using TCP 3

4 Eclipse Paho Android Example Assume that Java JDK version 6 or higher package is used for implementation in Paho. Also Android Software Development Kit (SDK) is installed and Android Development Toolkit (ADT) is added as plugin to the Eclipse. Package org.eclipse.pahoandroidapplicationexample; import org.eclipses.paho.client.mqttv3.mqttclient; import org.eclipses.paho.client.mqttv3.mqttexception; import org.eclipses.paho.client.mqttv3.mqttmessage; 4

5 Devices using MQTT Clients Kettle Electric Temperature Sensor and controller 1:Published Sensed data 10s of Bytes 4:Subscribed Control data 10s of Bytes IoT or M2M Area Local Network and Gateway Network and Transport MQTT broker (m2m. eclipse. org/ paho Android Applications and Services Layer MQTT Clients 2:Subscribed Sensed data of Devices 3:Published control data for the devices Android App for Intenet control of home electric kettle Physical/Data Link Layer Adaptation Layer Network and Transport Layers Layer Application Support/ Mobile Service Provider Layer Application Layer Fig. 9.3 Connected Sensor and Actuator publishing the sensed data and subscribing for the control data using MQTT Android clients communication with Application layer MQTT clients through an MQTT Broker

6 Example 9.12 Eclipse Paho Java implementation of MQTT clients-broker architecture Communication of sensed data to the applications and central controller for the control of electic kettle Implement the Subscriber class for subscribing to the sensed data (for example Electric Kettle Temperature Sensor) by the Android phone 6

7 Step (i) /*Let first step is that within the class Subscriber, declare URL of the MQTT Broker and create instance of class MQTTClient Use MAC Address as Client_ID for publisher ID and the initialization of the MqttClient instance Use -subandroid as a suffix for the Client_Id. */ public class Subscriber { public static final String MQTT_BROKER_URL = tcp://broker.mqttdashboard.com:1883 ; 7

8 Step (ii) /* client is the instance of MqttClient */ private MqttClient client; public Subscriber() { String a1 = -subandroid ; /* Declare clientdevice_id using method getphonenumber( ). */ 8

9 Step (ii) String clientdevice_id = Utils.getPhoneNumber () + a1; try { mqttclient = new MqttClient(MQTT_BROKER_URL, clientdevice_id); } catch (MqttException e) { 9

10 Step (ii) /* Write codes for callback method */ /* On exeception, Assume that callback method is print the stack trace. */ e.printstacktrace(); System.exit(1); }} } 10

11 Summary We learnt Example for the usages of Paho for Android MQTT clients for controlling an Electric Kettle. Chapter-9 L14: "Internet of Things ", Raj Kamal, 11

12 End of Lesson 14 on Program implementation using Paho and ADT Example 9.12 in MQTT clients and MQTT broker communication with an Android phone Chapter-9 L14: "Internet of Things ", Raj Kamal, 12