\begin{sequencediagram}
    \newthread{actor}{Actor}{}
    \newinst[4]{concordia}{:Concordia}{}
    \newinst[4]{eth}{:Ethereum}{}
    \newinst{orbit}{:OrbitDb}{}

    \begin{call}{actor}{Create community}{concordia}{Community creation form}
    \end{call}

    \begin{call}{actor}{Add external contract}{concordia}{External contract form}
    \end{call}

    \begin{call}{actor}{Submit}{concordia}{Created community page}

        \begin{call}{concordia}{Create community}{eth}{New community ID}
        \end{call}

        \begin{call}{concordia}{Connect external contract}{eth}{}
        \end{call}
    \end{call}
\end{sequencediagram}