Develop the Data Transfer Object

There are three major tasks we look at during the development of the mock user interface. They are:

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

Data transfer object

Here, the data transfer object does not have the Cart entity. Since the Customer and Cart share a one-to-one relationship, in an instance of Customer there can be only one instance of the Cart.

We are hiding from the user that we are saving the relationship as a one-to-one bi-directional relationship.