Can I use the plantUML language in LaTeX?

I use the website https://www.planttext.com/ to export to/download as SVG (which btw includes the plantuml code as XML comment) and after that save as PDF with inkscape. This can be used with includegraphics

You could also write the plantuml diagrams localy and convert them via plantuml -teps your-file to lossless eps files. These can be directly included in latex via the includegraphics command.

This way you do not have to go the way via inkscape.

I have worked out a solution that works with pdflatex as well. It produces vector graphics. I tested it with Ubuntu Linux 20.04 LTS and TeX Live. Should work with macOS as well.

My code requires, that you have installed:

• PlantUML (thus, also Java)
• Inkscape (converting svg to pdf)

Due to calling external commands, you have to use the -shell-escape option to compile:

pdflatex -shell-escape my-file.tex

Depending of how you installed PlantUML, you might have to call it like this:

immediatewrite18{java -jar /home/NAME/Downloads/plantuml.jar -tsvg #1.txt}

... instead of ...

immediatewrite18{plantuml -tsvg #1.txt}

Here is the full code as minimal example:

documentclass[a4paper,12pt]{article}
usepackage[utf8]{inputenc}
usepackage{graphicx} % enables us to use graphics
usepackage{fancyvrb} % enables us to write to disk
usepackage{float}    % enables us to use [H] for figures

% Define an verbatim environment for PlantUML:
newenvironment{plantuml}[1]{VerbatimOut{#1.txt}}{endVerbatimOut}

% Process a PlantUML code:
newcommand{process}[3]{%
    % Call PlantUML to produce a svg vector graphcis:
    immediatewrite18{plantuml -tsvg #1.txt}
    % Call Inkscape to convert the svg to a pdf (pdflatex cannot use svg):
    immediatewrite18{inkscape #1.svg --export-filename=#1.pdf}
    % Include the pdf:
    begin{figure}[H]
        includegraphics[width=#2]{#1.pdf}
        caption{#3}
    end{figure}
    % Remove all intermediate files:
    immediatewrite18{rm #1.txt #1.svg #1.pdf}
}

begin{document}

% Note: timeline1 gets used as filename.
%       You must re-use this name for the
%       corresponding process command!
begin{plantuml}{timeline1}
    @startgantt
        [Prototype design] lasts 15 days
        [Test prototype] lasts 10 days
    @endgantt
end{plantuml}
process{timeline1}{0.8textwidth}{The proposed timeline.}

begin{plantuml}{activity1}
    @startuml
        :Hello world;
        :This is on defined on
        several **lines**;
    @enduml
end{plantuml}
process{activity1}{5cm}{An activity diagram.}

end{document}

I hope this is helpful to someone.