Aggregation

Tags: modelling

Is a relationship between two entities expressing a [see page 23, whole-parts] relationship. If the whole is broken down the parts continue to exist.

\begin{figure}
  \centering
  \begin{tikzpicture}
    \umlclass{Bicycle}{
      serialNumber: Integer \\
      brand: String}{};
    \umlclass[x=7]{Wheel}{
      diameter: Integer \\
      tyrePressure: Real}{};
    \umlsimpleclass[x=-1, y=-3]{Fork};
    \umlsimpleclass[x=1, y=-3]{Frame};
    \umlVHVaggreg[pos2=2.8, attr2=fork|1]{Bicycle}{Fork};
    \umlVHVaggreg[pos2=2.8, attr2=frame|1]{Bicycle}{Frame};
    \umlaggreg[attr2=wheels|2]{Bicycle}{Wheel};
  \end{tikzpicture}
  \caption{Example of an aggregation relationship. If the bicycle stops existing the
individual parts it's made up of will continue to exist therefore it's an
aggregation.}
\end{figure}