Java Reference
In-Depth Information
Presentation Tier
Web Component
...
Business Tier
Façade
<< session EJB>>
PlaceOrderFaçade
<<pojo>>
PlaceOrderFaçade
Domain Model
PlaceOrderService
PendingOrder
Repository
...
PendingOrder
Restaurant
Persistence Framework
Figure 3.1
The relationship of the domain
model with parts of the application
Database
3.1.2
An example domain model
A domain model consists of a network of interconnected objects, many of which
have both state and behavior. As well as storing data, a domain model object usually
implements the business logic that operates on that data. Most of the classes in a
typical domain model are specific to the application's problem domain. A banking
application's domain model contains classes such as
Account
and
Transaction
whereas the Food to Go application's domain model contains classes such as
Order
and
Restaurant
. It's always helpful to see an example, so let's focus on part of the
domain model for the Food to Go application, which is shown in figure 3.2.
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