\begin{frame}[fragile]
  \frametitle{Object Relational Mapping}
  
  \begin{goal}{Object Relational Mapping}
    Maps rows in tables to objects:
    \begin{itemize}
      \item table $\approx$ class
      \item row $\approx$ object
      \item foreign key navigation $\approx$ pointers / references
    \end{itemize}
  \end{goal}
  \bigskip
  
  \begin{tcenter}
  \scalebox{.8}{
  \begin{tikzpicture}
    \umlclass{Event}{ 
      +name \\
      +date 
      }{ 
      } 
    \umlclass[x=3.4]{Venue}{ 
      +name
      }{ 
      } 
    \umlassoc[arg1=0..*,pos1=0.3,arg2=1,pos2=.8,name=assoc]{Event}{Venue} 
    \node [align=left,fill=blue!10,rectangle,rounded corners=1mm,dashed,draw,inner sep=2mm] at (-6.5,0) {
      \small\texttt{public class Event \{}\\
      \small\texttt{\ \ String getName();}\\
      \small\texttt{\ \ String getDate();}\\
      \small\texttt{\ \ Venue getVenue();}\\
      \small\texttt{\}}
    };
    
    \node [align=center,draw,fill=red!10] (m) at (-2.8,0cm) {mapping};
    \draw [ultra thick,red,->,>=triangle 45] (m) -- +(1.7cm,0cm);
    \draw [ultra thick,red,->,>=triangle 45] (m) -- +(-1.7cm,0cm);
  \end{tikzpicture}
  }    
  \end{tcenter}
  \pause\smallskip
  
  \begin{goal}{Ingredients}
  \begin{itemize}
    \item mapping from objects to database (automatic or designed)
    \item run-time library handles interaction with the database
  \end{itemize}
  \end{goal}
  
  Many ORM toolkits: Hybernate, RubyOnRails, ADO.NET,\ldots
\end{frame}