Develop the Data Transfer Object

We will divide the mock user interface development into the following three major tasks:

• the data transfer object
• the mock service
• the mock user interface

Data transfer object

When the database service is ready, we will create the actual user interface and integrate it.

The data transfer object encapsulates the actual entity design and does not allow the user interface or the client to know the entity design underneath.

Look at the data transfer object carefully, you will see the identifier of the Book object along with a name and city field. We are not exposing the Shipping entity or its identifier. We form a relationship between the Book and Shipping in the service, but to the user, it is one object called Book.

This is particularly useful for the user interface team as they do not have to manage the Shipping entity identifier and can just call the service as one object.