I am drawing an attached sequence diagram but some of the components couldn't figure out (highlighted in red boxes(red boxes are not required)). Please advice
\documentclass{article}
\usepackage{pgf-umlsd}
\begin{document}
\begin{figure}
\centering
\begin{sequencediagram}
\newthread{FD}{FirstObject}{}
\newinst[2]{FH}{SecondObject}{}
\newinst[2]{VM}{ThirdObject0}{}
\newinst[2]{FC}{FourthObject0}{}
\begin{call}{FD}{processEvent()}{FH}{}
\begin{call}{FH}{processEvent()}{VM}{processEvent()}
\begin{call}{VM}{processEvent()}{FC}{processEvent()}
\end{call}
\begin{call}{VM}{processEvent()}{VM}{}
\end{call}
\end{call}
\end{call}
\end{sequencediagram}
\end{figure}
\end{document}
pgf-umlsd
does only provide self calls with two arrows. Maybe the packagetikz-uml
(manual see here) would be better suited.