Datasheet

Chapter 1 ✦ What Is UML?

Goal 4: Provide a formal basis for understanding the modeling

language

The language must be defined at a level that is precise yet accessible. Without pre-

cision, the models do not help define a real solution. Without accessibility, no one

will use it. The UML standard uses Class diagrams to represent the formal defini-

tions of objects and their relationships. Each Class diagram is supplemented with

text detailing the semantics and the notation options. The constraints that define

the integrity of the model elements are expressed using Object Constraint Language

(OCL). (See Chapter 18.)

Goal 5: Encourage the growth of the object tools market

The modeling tool market is dependent on a unified standard for modeling, for the

model repository, and for model interchange. To the extent that vendors can rely

on a stable standard, they can quickly and effectively implement all three funda-

mental tool features. As the vendors’ cost to provide the core functionality

decreases, vendors are freed to pursue value-added modeling-environment

enhancements such as integration with coding environments, database manage-

ment tools, syntax checking, model verification, and more.

We are seeing the effect of the standard today. The number of tools has mush-

roomed, and the feature sets offered in the tools have exploded. Where tools used

to focus almost exclusively on just being able to draw diagrams, today they are per-

forming syntax checking of OCL statements, diagram synchronization, code genera-

tion and reverse engineering, importing from various other tools, exporting HTML

or XML reports, supporting integration with one or more coding environments, and

much more.

Goal 6: Support higher-level development concepts such as

components, collaborations, frameworks, and patterns

The standard needs to support the modeling of higher-level concepts such as

frameworks, patterns, and collaborations. Doing so supports the advancement

of modeling and systems development. By ensuring this future potential, UML

becomes an asset that facilitates technological evolution rather than being

one more legacy that has to be dragged into the future with all the other old

technologies.

The scope of the UML

UML is designed to be the merging of best development practices and the leading

modeling concepts of the past 30 years. There is also a deliberate effort to take into

account the fact that development technologies and techniques are always changing.

With such an ambitious goal, it would be easy to fall into the trap of making UML

define everything — modeling, development methodology, project management,

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