Modeling with UML - Software Engineering: A Hands-On Approach - page 54

Real Estate Server

Bank Server

Mortgage Application Listing

<<Database>>
CustomerDB

<<Storage>>
MultipleListings

component

Interface

IMortgageApplication IListing

node

dependency

a PC

BuyerInterface

TCP/IP TCP/IP

connection

Fig. 3.20 Deployment diagram (Miller 2003 )

system. This practice leads to the use of interfaces to allow controlled commu-
nication with an entity while concealing that entity's inner working from the user.
An interface is, of course, an integral part of the software system, and must be
designed, implemented, and documented like any other portion of a software
engineering project. Figure 3.21 shows an interface in a component diagram,
represented by a circle containing the interface's name.
It is important to note that a component may implement any number of inter-
faces (including none at all), and that multiple components may implement the
same interface.

3.5.2 Packages

A package is a ''UML grouping concept denoting that a set of objects or classes
are related'' (Bruegge and Dutoit 2004 ). Essentially, a package is a collection of
related models. Figure 3.22 illustrates this concept.
As evidenced in this diagram, a package is denoted in UML by a single tab
containing the package name. In Fig. 3.22 , ''Sched'' is the package name. A
package is a development concept used for grouping, as distinct from a compo-
nent, which exists at runtime.

Fig. 3.21 Component

SomeInterface

interface

SomeComponent