Composition

Tags: modelling

Is a relationship between 2 entities expressing a [see page 23, whole-parts] relationship where the parts depend on the owning whole. If the whole is broken down the parts cease to exist.

\begin{figure}
  \centering
  \begin{tikzpicture}
    \umlclass{Order}{
      orderNumber: Integer \\
      date: Date}{};
    \umlclass[y=-5]{OrderLine}{
      productCode: Integer \\
      quantity: Integer \\
      price: Real}{};
    \umlaggreg[attr2=lines|1..*]{Order}{OrderLine};
  \end{tikzpicture}
  \caption{Example of a composition relationship. Individual order-lines cannot exist
without the owning order.}
\end{figure}