Association Aggregation Composition

• Association
  (1)擁有自己的生命周期(LifeTime)
  (2)物件本身並沒有Owner的觀念
  (3)物件為各自獨立關係(independent)
  (4)UML表示圖為單一箭頭
• Aggregation
  (1)擁有自己的生命周期(LifeTime)
  (2)擁有Owner(例如:"Manager" object will own "Workers" object.)
  (3)
  (4)UML表示圖為空心菱形
• Composition
  (1)若Owner生命週期結束，則另一方也結束
  (2)擁有Owner
  (3)關係為緊密相依(dependent)
  (4)UML表示圖為實心菱形
  
  關係請參考下列圖例：(擷取自3 Important Concepts: - Association, Aggregation and Composition)

關係表：

	Association	Aggregation	Composition
Owner	No Owner	Single owner	Single Owner
Life time	Have their own life time.	Have their own life time.	Owners life time
Child object	No Child objects all are independent	Child objects belong to single parent.	Child objects belong to single parent.

參考：3 Important Concepts: - Association, Aggregation and Composition