Server Communicating with the Device

When you send a command to a device, it goes through the WSO2 IoTS transport sender mechanism. For example, switching on or switching off the bulb on the RaspberryPi device type. To identify the flow of what happens when WSO2 IoTS receives the command, and how it communicates take a look at the diagram given below:

Let's understand this clearly by using the RaspberryPi device type:

Write the API to switch the bulb on. Once WSO2 IoTS receives the command it will call the API you have written to switch the bulb on.

For more more information, see Writing Device APIs.
Define the operation type for the API in the <DEVICE_TYPE>SeviceImpl.java file. WSO2 IoTS supports the following 4 operation types.
- POLICY
- COMMAND
- CONFIG
- PROFILE
Example: The RaspberryPiServiceImpl.java file has configured the bulb switching on and off API as a COMMAND operation.
```
Operation commandOp = new CommandOperation();
commandOp.setCode("bulb");
commandOp.setType(Operation.Type.COMMAND);
commandOp.setEnabled(true);
commandOp.setPayLoad(actualMessage);
```

The command then get's stored in the database for monitoring purposes and gets sent to push notifications.

The push notification providers in WSO2 IoT Server don't meet your requirement? You can create your own push notification. For more information, see Adding a Push Notification Provider.

The push notification method is implemented in the device plugin deviceManagerService.java file.
Example: RaspberrypiManagerService.java

public PushNotificationConfig getPushNotificationConfig() {
 Map < String, String > properties = new HashMap < > ();
 properties.put("mqttAdapterName", "sampledevice_mqtt");
 properties.put("username", "admin");
 properties.put("password", "admin");
 properties.put("qos", "0");
 properties.put("clearSession", "true");
 properties.put("scopes", "");
 return new PushNotificationConfig("MQTT", false, properties);
}

You can define the control type and other statistics for the push notification to take place.

Configure and save the file containing the statisticsProps configurations anywhere you prefer.
Example: The statisticProps for the virtual fire alarm are defined in the <IoTS_HOME>/repository/deployment/server/devicetypes/raspberrypi.xml file.

<PushNotificationConfiguration>
   <!--MQTT Config-->
   <PushNotificationProvider>MQTT</PushNotificationProvider>
   <Properties>
      <Property Name="mqtt.adapter.name">raspberrypi.mqtt.adapter</Property>
      <Property Name="url">tcp://localhost:1883</Property>
      <Property Name="username">admin</Property>
      <Property Name="dcrUrl">https://localhost:9443/dynamic-client-web/register</Property>
      <Property Name="qos">0</Property>
      <Property Name="scopes" />
      <Property Name="clearSession">true</Property>
   </Properties>
</PushNotificationConfiguration>

Make sure to define the dcURL for the transport.

The command is then sent to the device.
Follow the steps given below to find out if the device received the command:
1. Sign in to the WSO2 IoTS device management console.
  Click here for more information.
  Follow the instructions given below to start WSO2 IoT Server, and sign into the device management console:
  Navigate to the WSO2 IoT Server pack's samples directory and run the device-plugins-deployer.xml file.
  Why is this needed?
  
  Before enrolling devices with WSO2 IoT Server you need to have the device type plugins created. The Android, Android Sense, Windows, and Android Virtual Device sample device type plugins are available by default on WSO2 IoT Server. You need to run the command given below to create the Raspberry Pi, Arduino, and Virtual Fire Alarm sample plugins.
  For more information on writing your own device plugin, see Writing Device Types.
  Example:
  
  cd <IOTS_HOME>/samples mvn clean install -f device-plugins-deployer.xml
  
  Start WSO2 IoT Server by starting the three profiles in the following order:
  Start the broker profile, which corresponds to the WSO2 Message Broker profile.
  
  The default port assigned for the broker is 9446.
  Start the core profile, which corresponds to the WSO2 Connected Device Management Framework (WSO2 CDMF) profile.
  
  The default port assigned for the core is 9443.
  Start the analytics profile, which corresponds to the WSO2 Data Analytics Server profile.
  
  The default port assigned for analytics is 9445.
  Access the device management console by navigating to https://<HTTPS_HOST>:<HTTPS_PORT>/devicemgt.
  Example: https://localhost:9443/devicemgt
  Enter your username and password.
  If you are new to using WSO2 IoT Server, you need to first register before you can to log into the WSO2 device management console.
  Click here for more information on registering with WSO2 IoT Server.
  
  Follow the instructions given below to register with WSO2 IoT Server:
  Click Create an account
  
  Fill out the registration form.
  First Name: Provide your first name.
  Last Name: Provide your last name.
  Username: Provide a username. It should be at least 3 characters long with no white spaces.
  Email: Provide a valid email address.
  Password: Provide a password. It should be at least 8 characters long.
  Confirm Password: Provide the password again to confirm it.
  Click Register.
  
  Click LOGIN.
2. Click the device you sent the command.
  Example: Click virtual fire alarm.
3. Click Operation logs, to view the status of the command you sent.
  The operation status can be any of the following values:
  - IN-PROGRESS - The operation is processing on the IoTS server side and has not yet been delivered to the device.
  - PENDING - The operation is delivered to the device but the response from the device is pending.
  - COMPLETED - The operation is delivered to the device and the server has received a response back from the device.
  - ERROR - An error has occurred while carrying out the operation.