\begin{algorithm}                      % enter the algorithm environment
\caption{procedure DOWNLOAD} % give the algorithm a caption
\label{SaS:DOWNLOAD}
\STATE {\bf procedure} user\_request($follower\_id$, $friend\_id, content\_id, home\_server, friend\_surrogate$)
\begin{algorithmic}[1]                    % enter the algorithmic environment
        \REQUIRE USER ID,home\_servere
    \ENSURE URL of requested content
    \STATE content$\leftarrow$request\_redirect(content\_id)
        \IF{content$!=$server}
                \STATE schedule\_pull(content\_id,server)
        \ENDIF
   \STATE {{\bf return} $content\_host$}
\STATE {{\bf end procedure}
\end{algorithmic}
\end{algorithm}