J2EE design decisions - POJOs in Action: Developing Enterprise Applications with Lightweight Frameworks - page 49

The restaurant acknowledges receipt of the order. 3

A dispatcher assigns a driver to the order.

4

The system sends a notification to the assigned driver. 5

The driver views the assigned order on a cell phone.

6

The driver picks up the order from the restaurant and notifies the system
that the order has been picked up.

7

The driver delivers the order to the customer and notifies the system that
the order has been delivered.

8

In addition to coming up with a scenario that captures the vision of how the appli-
cation will ultimately work, the developers and businesspeople also break down
the application's requirements into a set of use cases. Given that Food to Go has
limited resources, the team has decided to use an iterative and incremental
approach to developing the application. They have decided to defer the imple-
mentation of use cases for dispatches and drivers to later iterations and to tackle
the following use cases in the first iteration:

Place Order —Describes how a customer places an order

■

View Orders —Describes how a customer service representative can view orders

■

Send Orders to Restaurant —Describes how the system sends orders to restau-
rants

■

Acknowledge Order —Describes how a restaurant can acknowledge receipt of
an order

■

Modify Order —Describes how a customer service representative can modify
an order

■

These use cases are used throughout this topic to illustrate how to develop enter-
prise Java applications with POJO s and lightweight frameworks. I describe each of
these use cases in a bit more detail later in this chapter, but let's first look at the
application's high-level architecture.

The application's architecture
In the kickoff meeting, the team also sketches out the application's high-level
architecture, which is shown in figure 2.7. This diagram shows the application's
main components and its actors. It has the standard three-layer architecture con-
sisting of the web-based presentation, business, and database access tiers. As you
would expect, the application stores its data in a relational database.