Faceless Component 

Should you require it, it is possible to create a Web Dynpro component that has no visual interface. In other words, it is a component with zero views and zero windows. Such a component is known as a faceless component and is useful when a complex unit of functionality requiring no direct user interaction needs to be encapsulated.

A good example of a faceless component is the creation of something called a model component. This is not a specific Web Dynpro component type; rather it is a standard Web Dynpro component that has been written specifically for the task of interacting with a model object.

Often, a model object could have a large and complex interface. Since model objects are completely reusable, it does not make sense to have to reimplement the functionality required to interact with the model object every time it is reused. Therefore, SAP recommends that when a model object’s interface requires any type of additional processing or simplification, that the model object be encapsulated within a component in order to be able to reuse the associated interface coding. Very often (though not exclusively) a model component will have no visual interface, thus making it a faceless component.

The model component then becomes the unit of reuse rather than the model object.