UML - Unified Modeling Language

What is UML ?

UML is an object-oriented, graphic analysis and design standard from the Object Management Group (OMG). It defines nine kinds of diagram.

1. Use Case Diagram: Shows a systems functions from a user's point of view
2. Sequence Diagram: Shows message flow between entities in the system
3. Collaboration Diagram: Shows the structure of relationships between entities
4. Class Diagram: Shows "classes" of system entities. Each class has "attributes" and "operations". Lines between classes are "associations".
5. State Chart: Describes the discrete states which are possible in the system.
6. Component Diagram: Shows software module interaction
7. Deployment Diagram: Shows hardware nodes
8. Activity Diagram: Shows tasks
9. Object Diagram: Shows instantiations of classes (rarely used)

When to Use UML

UML is most useful on large projects particularly those which use Object Oriented Development. It is a relatively "heavy" environment requiring specialized skills and software (see below). It should be used on projects like air traffic control or online banking where "you must get it right first time".

Resources

UML FAQ This is a great site to get a general understanding of UML. It is provided by Rational Software.
UML Resource Center Hosted by Rational Software Corporation, this site includes UML reference documentation as well as many do how to use documents about UML.
UML Publications Links to online articles and reference guides provided by Mario Jeckle.
UML Specifications Links to various UML official specifications documents again provided by Mario Jeckle.

Software Tools

Tau from Telelogic provides a set of development tools including:
- Tau UML Suite for requirement capture, analysis and OO design,
- Tau SDL Suite for design and implementation,
- Tau TTCN Suite for comprehensive testing,
- Tau Logiscope to detect coding errors, identify and locate error-prone modules, provide code coverage analysis,
- Tau SCADE for the cost and time effective development of safety critical software.

Background

In the late 1980's, a proliferation of modeling languages meant that when modeling specialists changed jobs, or even projects, they had to learn a new set of tools. The leading specialists, Grady Booch (Rational Software), James Rumbaugh (Object Modeling Technique), and Ivar Jacobson (Use Cases) among others, agreed on a modified version of a notation originally developed by David Embley and his colleagues. The UML was published by the Object Management Group in 1997..

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