Learning UML 2.0

Chapter 1. Introduction

The Unified Modeling Language (UML) is the standard modeling language for software and systems development. This statement alone is a pretty conclusive argument for making UML part of your software repertoire, however it leaves some questions unanswered. Why is UML unified? What can be modeled? How is UML a language? And, probably most importantly, why should you care?

Systems design on any reasonably large scale is difficult. Anything from a simple desktop application to a full multi-tier enterprise scale system can be made up of hundreds—and potentially thousands—of software and hardware components. How do you (and your team) keep track of which components are needed, what their jobs are, and how they meet your customers’ requirements? Furthermore, how do you share your design with your colleagues to ensure the pieces work together? There are just too many details that can be misinterpreted or forgotten when developing a complex system without some help. This is where modeling—and of course UML—comes in.

In systems design, you model for one important reason: to manage complexity. Modeling helps you see the forest for the trees, allowing you to focus on, capture, document, and communicate the important aspects of your system’s design.

A model is an abstraction of the real thing. When you model a system, you abstract away any details that are irrelevant or potentially confusing. Your model is a simplification of the real system, so it allows the design and viability ...