Using the Transaction Script pattern - POJOs in Action: Developing Enterprise Applications with Lightweight Frameworks - page 336

DTO s to pass data to the DAO s in order to update the database. They are also
returned by the transactions scripts to the presentation tier.
DTO s are simple data holders and only have fields and getters. The DTO s and
their fields can be identified in one of three ways:

Define a DTO for each database table that has fields corresponding to the
table's columns.

■

Define a DTO for each screen whose fields contain the data that is displayed
on the screen.

■

Perform simple OO analysis and design techniques to identify the classes
and their fields.

■

For this particular use case, we can apply a combination of these techniques and
get the DTO s shown in figure 9.5.
The names of these DTO s, their fields, and their associations are very similar to
the names, fields, and associations of the classes in the domain model described
earlier in chapter 3. However, one very important difference is that unlike the
domain model classes, they do not implement any business logic. Listing 9.3
shows an excerpt of the source code for the PendingOrderDTO that illustrates the
simple structure of a DTO .

PendingOrder
DTO

PendingOrder
LineItemDTO

Address

pendingOrderId
state
deliveryTime

quantity

Payment
Information

Restaurant
Summary
DTO

MenuItem
DTO

Restaurant
DTO

menuItemId
name
price

restaurantId
name

restaurantId
name

Figure 9.5 Design of the details classes