% Tikz File mqtt_pub_sub.tex \documentclass{standalone} \usepackage{tikz, graphicx} \begin{document} \begin{tikzpicture} %\draw[help lines] (-7,-5) grid (7,5); \pgfmathsetmacro\pub{-4}; \pgfmathsetmacro\bro{0}; \pgfmathsetmacro\sub{4}; \pgfmathsetmacro\y{4}; \draw[ultra thick] (\pub,\y/2) -- (\pub,\y/-2); \draw[ultra thick] (\bro,\y/2) -- (\bro,\y/-2); \draw[ultra thick] (\sub,\y/2) -- (\sub,\y/-2); \draw[ultra thick, ->] (\sub,1) -- (\bro, 1); \draw[ultra thick, <-] (\sub,-1) -- (\bro, -1); \draw[ultra thick, ->] (\pub,0) -- (\bro, 0); \node at (\pub, \y/2+0.2) {Publisher}; \node at (\bro, \y/2+0.2) {Broker}; \node at (\sub, \y/2+0.2) {Subscriber}; \node at (\sub/2, 1.2) {Subscribe (topic)}; \node at (\pub/2, 0.2) {Publish (topic, info)}; \node at (\sub/2, -0.8) {Publish (topic, info)}; \end{tikzpicture} \end{document}