使用 latex 的序列图

Question

我想要绘制如下的序列图：

这是我的代码：

% arara: pdflatex
% arara: clean1
% arara: clean: { files: [ Commands.aux , .main.ptd , TP.aux] }
 \documentclass{article}
 \usepackage[a3paper,landscape]{geometry}
\usepackage{pgf-umlsd}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\usepackage{xcolor}
    \definecolor{ultramarine}{rgb}{0.91, 1.0, 1.0}

\begin{document}

  \centering
    \scalebox{1}
    {  \begin{sequencediagram}
    \newthread{A}{\shortstack{\begin{tikzpicture}
\node [fill=ultramarine,draw=black,thick ,align=center] {A };
\end{tikzpicture}}}
    \newinst{B}{\shortstack{\begin{tikzpicture}
\node [fill=ultramarine,draw=black,thick ,align=center] {B };
\end{tikzpicture}}}
    \newinst{C}{\shortstack{\begin{tikzpicture}
\node [fill=ultramarine,draw=black,thick ,align=center] {C };
\end{tikzpicture}}}

\begin{messcall}{A}{ A2B }{B}
 \end{messcall}

\begin{messcall}{B}{B2C }{C}
\end{messcall}
  \end{sequencediagram}
  }
\end{document}

并输出：