\begin{frame}{Centralized Revision Control}
  Single repository, multiple working copies:
  \begin{center}
    \begin{tikzpicture}[remember picture]
      \tikzstyle{working copy}+=[below]

      \node[repository, label=above:Repository] (repository) {};
      \node[rev] (r1) at (-7mm, 0) {};
      \node[rev] (r2) at (0, 0) {};
      \node[rev] (r3) at (7mm, 0) {};
      \draw[->] (r1) -- (r2);
      \draw[->] (r2) -- (r3);


      \node[working copy, label=below:Alice] (wa) at (-2, -2) {
        hello.c\\
        Makefile
      };

      \node[working copy, label=below:Bob, text width=18mm] (wb) at (2, -2) {
        goodbye.c\\
        Makefile
      };

      \draw[<->, short] (wa) -- (repository);
      \draw[<->, short] (wb) -- (repository);

      \node<2>[box, text width=5cm]  at (current page.center) {
        Drawbacks:
        \begin{itemize}
        \item network latency
        \item single point of failure
        \item contrained workflow
        \end{itemize}
      };
    \end{tikzpicture}
  \end{center}
\end{frame}