UML

PlantUML

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Updated: 03 August 2026

Quick start

See https://plantuml.com/starting

  1. Go to https://plantuml.com/download and choose the GPL compiled jar.
  2. Launch the PlantUML GUI with java -jar plantuml.jar -gui
  3. With the GUI, navigate to a directory containing plantuml text files. The UML image files should be automatically created in the same directory.

Or without the GUI, watch a directory for changes and re-generate image files automatically

java -jar plantuml.jar -watch ./trading-uml

Convert a single puml file to a png image.

java -jar ~/plantuml-1.2026.6.jar backing-up.puml

Use Case

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Updated: 31 August 2024

  • Actors can be related e.g. an International Student IS A Student.
  • Use packages to group similar Actors or Use Cases.

Composition vs Aggregation

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Updated: 04 April 2025

An example with PHP:

/* COMPOSITION */
/* If human object is deleted heart object is deleted also. */
class Heart{}

class Human{
    private $heart;
    public function addHeart(){
        $this->heart = new Heart();
    }
}

$human = new Human();
$human->addHeart();

/* AGGREGATION */
/* If car object is deleted engine object still exists. */
class Engine{}

/* The Aggregate */
class Car{
    private $engine;
    public function __construct(Engine $engine){
        $this->engine = $engine;
    }
}

$engine = new Engine();
$car = new Car($engine);