UML Weekend Crash Course™ - To Parent Directory

Session 24—Modeling the Development Environment 249
Model elements in a package
One of the most common uses for the package is to hold your diagrams. In most modeling
tools, packages provide a nesting mechanism (that is, a package may contain other packages,
which in turn contain diagrams). The packages in this scheme refer to systems, subsystems,
and diagrams, respectively. The scheme can contain as many levels as the problem
requires. Figure 24-6 shows an example of the package Shipping that holds the Class diagram
that supports the functions of the Shipping subsystem.
Shipping
ships
1..1
0..*
Shipping Clerk
1..1
packs
0..*
Shipment ship OrderProcessing::Order
0..* 1..1
0..1
0..1
1..*
Purchasing::Product
1..*
Figure 24-6 A package containing a Class diagram
Actually, the more common way to represent this in a modeling tool is to open a package
and get a diagram in a new window or canvas. Conceptually, the diagram resides in the
package as I have represented in Figure 24-6. But the tool does not represent it that way.
Figure 24-6 also shows two examples of the import relationship. The Order and Product
classes use the qualifying notation package :: element. This notation tells you that the two
classes came from the named package (that is, Order is imported from the OrderProcessing
package and Product is imported from Purchasing). This clearly identifies the fact that the
class is defined in another package but is referenced in this package.