Class Diagram Example: GoF Design Patterns - Facade


Facade design pattern is one of the Gang of Four (GOF) design patterns. Facade design pattern supplies a single interface to a set of interfaces within a system.

Use this Facade design pattern template as a starting point to build your class model, or click Create Blank to start from scratch.

What is Class Diagram?

A class diagram is primarily designed for developers to provide the conceptual model and architecture of the system being developed. A class diagram provides the overview and structure of a system in terms of classes, attributes and methods, and the relationships between different classes.

Class diagrams are at the heart of UML. A class diagram carries different information depending on the phase of the development process and the level of detail being considered. As development progresses, a class diagram moves towards the implementation domain, which is familiar to software developers. Class diagrams are a vital part of any software development project and they form the foundation of all software products.

Guidelines for creating Class Diagram?

  1. Identify classes
    • a. From domain analysis such as textual analysis
    • b. From CRC cards
    • c. From use case description
    • d. From sequence diagram or use case scenarios
  2. Give analysis a name and a brief description which could be done through terms and glossary
  3. Structure classes in the right places of the diagram and related them with simple relationships
  4. As the development move forward, detail the class with attributes and operations, this often done in conjunction with use case and sequence diagrams
  5. Refine the class diagram with inheritance for future reuse
  6. Elaborate the details which is helpful for implementation such as accessibility, rules, constraints and etc.
  7. Put related classes into packages to form your software architecture

Why do we need class diagrams?

  • Plan and model requirements ahead of time make implementation much easier in subsequently phases.
  • Modify class diagrams quite is easy, whereas the actual code for features.
  • Plan for a house (not a simple dog house) to have a blueprint, before grab a hammer and nail to get work done.
  • Class diagram is quite easy to understand and to be used to communicate with other stakeholders for team afford.

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