\begin{sequencediagram}
    \newthread{actor}{Actor}{}
    \newinst[4]{concordia}{:Concordia}{}
    \newinst[2]{eth}{:Ethereum}{}
    \newinst[1]{orbit}{:OrbitDB}{}

    \begin{call}{actor}{Sign up}{concordia}{Sign up form}
    \end{call}

    \begin{call}{actor}{Submit}{concordia}{Personal information form}

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

        \begin{call}{concordia}{Create databases}{orbit}{}
        \end{call}

    \end{call}

    \begin{call}{actor}{Submit}{concordia}{Home page}

        \begin{call}{concordia}{Save personal information}{orbit}{}
        \end{call}

    \end{call}
\end{sequencediagram}