\begin{frame}{Central Workflow}
  Everybody has write access to a central repository:
  \begin{center}
    \begin{tikzpicture}[node distance=15mm]
      \node[repository, label=above:Repository] (central) {};
      \node[rev] (r1) at (-7mm, 0) {};
      \node[rev] (r2) at (0, 0) {};
      \node[rev] (r3) at (7mm, 0) {};
      \draw[->] (r1) -- (r2);
      \draw[->] (r2) -- (r3);

      \tikzstyle{repository}+=[minimum height=10mm, text width=10mm]

      \node[repository, label=below:Alice, left=of central] (a) {};
      \node[repository, label=below:Bob,   below left=of central] (b) {};
      \node[repository, label=below:Carla, below=of central] (c) {};
      \node[repository, label=below:Dan,   below right=of central] (d) {};
      \node[repository, label=below:Eve,   right=of central] (e) {};

      \draw[<->, short] (a) -- (central);
      \draw[<->, short] (b) -- (central);
      \draw[<->, short] (c) -- (central);
      \draw[<->, short] (d) -- (central);
      \draw[<->, short] (e) -- (central);
    \end{tikzpicture}
  \end{center}
\end{frame}