Writing Device Plugins via Java Code

To understand the device plugin implementation let's take a look at the Raspberry Pi device implementation. Follow the steps given below to create a new device plugin:

Implement an interface for Raspberry Pi. For more information, see the implementation of DeviceManagerService for Raspberry Pi.
Why is this step required?
WSO2 IoTS can have many device types. These device types will be registered on WSO2 CDMF when the OSGI runtime starts. For the new device type to be registered with the CDMF, it needs to have an interface that the OSGI identifies at its runtime. The DeviceManagementService interface is implemented for this reason. Therefore, it is important that you implement the DeviceManagementService interface extended from org.wso2.carbon.device.mgt.common.spi . DeviceManagementService. You are able to implement methods unique to a device by overriding the methods defined in the interface.
Example: Implementing the interface DeviceManagementService.
```
public interface DeviceManagementService extends ApplicationManager {
   void init() throws DeviceManagementException;
   String getType();
   DeviceManager getDeviceManager();
   ApplicationManager getApplicationManager();
   ProvisioningConfig getProvisioningConfig();
   PushNotificationConfig getPushNotificationConfig();
}
```
Click here to know more about the methods used to create the interface.
getType()
Retrieves the name of the device-type.
init()
Custom initialization implementations needs to be included here.
getDeviceManager()
Returns an object, which is an implementation of the interface org.wso2.carbon.device.mgt.common.DeviceManager.
getApplicationManager()
Returns an object, which is an implementation of the interface org.wso2.carbon.device.mgt.common.app.mgt.ApplicationManager.
getProvisioningConfig()
Returns the provisioning details, which includes the the name of the tenant domain the device-type needs to be registered to and indicates whether the device-type is to be shared with all the tenants (true represents that the device-type should be visible to all tenants and false meaning that it is not visible to other tenants.).
Implement the DeviceManager interface. For more information, see the implementation of DeviceManager for Raspberry Pi .
Why is this step required?

Implement the interface DeviceManager for Connected Cup via the org.wso2.carbon.device.mgt.common.DeviceManager in order to implement the getDeviceManager()method that is shown in step 1. The DeviceManager interface will be used for enrolling, disenrolling, activating and deactivating a device.
Create a Database Access Object (DAO) on the created DeviceManager interface to manage data source connections.

Register as an OSGI service.
Example:

ServiceRegistration raspberrypiServiceRegRef = bundleContext.registerService(DeviceManagementService.class.getName(), new RaspberrypiManagerService(), null);

RaspberrypiManagerService is the implementation of the interface showed in step 1.

Start the IoT Server.
```
cd <IoTS_HOME>
./wso2server.sh
```

How it works

The following section describes how a Raspberry Pi is enrolled using a created device plugin:

The device enrollment calls will be passed through the DeviceManager implementation in the DeviceManagerService.
The DeviceManager implementation implements the interface org.wso2.carbon.device.mgt.common.DeviceManager.
The implemented interface manages the data of the Raspberry Pi, such as information related to enrollment, status, ownership, claimable, license and tenant configuration.
The implementation needs to be included in an OSGI bundle. Once the bundle is activated, the device will be registered on the Connected Device Management Framework (CDMF).