Presentation model components should, where possible, encapsulate both the data from your business layer, and business logic and behavior. This helps to ensure data consistency and validity in the presentation layer, and helps to improve the user’s experience.

In some cases, your presentation model components may be the business entities from your business layer, directly consumed by the presentation layer. In other cases, your presentation model components may represent a subset of your business entity components, specifically designed to support the presentation layer of your application. For example, they may store the data in a format that is more easily consumable by your UI and presentation logic components. Such components are sometimes referred to as presentation entities.

When the business layer and presentation layer are both located on the client, a typical scenario for rich client applications, you will usually consume the business entities directly from the business layer. However, you may consider using presentation entities if you must store or manipulate the business data in a way that is distinct from the format or behavior of the business entities exposed by the business layer.

When the business layer is located on a separate tier from the presentation layer, you may be able to consume the business entities in the presentation tier by serializing them across the network using data transfer objects, and then resurrecting them as business entity instances on the presentation tier. Alternatively, you can resurrect the data as presentation entities if the required format and behavior differs from that of the business entities.