The DeviceClassObjectSpi – com.prosyst.mbs.services.hdm.spi.DeviceClassObjectSpi, represents the device functionalities. The DeviceClassObjectSpi aims to present each device functionality to Device Access in a universal way. These functionalities are represented either by a Device Class or a Functional Item.

• The device functionalities that are represented by Functional Item are Device Items. They are accessed via the DA API. The following descriptions are related to this topic.
• The device functionalities that are represented by Device Class are accessed via the HDM API (deprecated).

Below we will demonstrate a simple implementation of DeviceClassObjectSpi which is related to Functional Item Management specification. You can find more information on how to implement a Functional Item in the Functional Item Management Developer Guide – Defining Functional Items section. We will also demonstrate a basic implementation of a device item. More information on implementing your own device class objects using DeviceClassObjectSpi can be found in the Home Device Manager Developer Guide (deprecated).

The DeviceClassObjectSpi provided by the protocol adapter is marked as a Device Item in the following cases:

• The functional interface is annotated with @Item annotation and extends FunctionalItem interface.
• The functional interface is annotated with @Item annotation and does not extend FunctionalItem interface. The DeviceClassObjectSpi implementation does not implement FunctionalItem interface.
• The functional interface is not annotated with @Item annotation, but the DeviceClassObjectSpi implementation extends FunctionalItem interface.

The Device Item is a java interface that has a set of properties, operations and events that are generated if properties are changed. For detailed information refer to the Property Cache section. Each Device Item returned by the adapter must implement DeviceClassObjectSpi interface and also some functional interface.

When you implement an adapter you must follow a set of rules related to the implementation of the Device Item:

• Method getPropertyNames() must provide all item properties.
• Method getOperationNames() must provide all item operations.
• Method getPropertyMetaData(String) must return null.
• Method getOperationMetaData(String) must return null.

The following methods are not invoked at all by Device Access and the adapter does not need to implement them:

• FunctionalItem.setName(String)
• FunctionalItem.setTags(Set)
• FunctionalItem.getObjectClass()
• FunctionalItem.getItemMetadata()

The following methods are invoked only initially when device is added. Their values are used as initial values for device items accessed by applications:

• FunctionalItem.getUID() – Device Access will set the UID as it is to device item UID which is unique in the system.
• FunctionalItem.getName()
• FunctionalItem.getTags()
• FunctionalItem.getAttributes()

The DeviceClassObjectSpi type (getType()) is added to device item tags accessed by applications. It is better that adapters implement the method FunctionalItem.getTags() rather than getType().

In the Device Access Protocol Adapter Demo we create an abstract class, which implements DeviceClassObjectSpi and does not extend FunctionalItem interface, but provides default implementation of the FunctionalItem methods.

For more information refer to the Device Access Protocol Adapter Demo – com.prosyst.mbs.da.adapter-demo.

The full list of demos is in Device Access Demos.