Ideas for high-level data structure visualization?

Question

I want to create a (graphical) representation for a custom HL7 v2 message structure. In this scenario, I'm only concerned with the high-level message structure - the arrangement and usage of the segments of a message. The official documents (which are not available unless you pay for them, AFAIK) use a table notation like this:

In this structure, the different brackets denote optional [] and repeatable {} segments as well as alternatives <x|y|z>. Our custom structure is built upon this standard and basically appends a few segments and declares that we'll never use certain other segments. So far, we have simply mimicked the table-like structure, but I find that this is hard to read, especially with multiple nestend levels of conditional groups. I was thinking about converting the TikZ file tree example to represent the data structure, but with all the child [missing] entries and other peculiarities, I was wondering whether there are other (better?) options.

Answer 1

I wholeheartily agree that the current format you are using is awkard and possibly it casts a light as to the many reasons that health software projects fail; which IMHO is due to bureaucratic complexification. Having to pay for the formats adds insult to injury.

I would recommend to use Lua. If you generating the data for typesetting programatically, I would use Lua tables directly. If they are generated from a db, either export them as XML or preferably json. Here is a simplified program to demonstrate this. No need for any railroads or boxes, you can read the data like a paragraph from a book.

  \documentclass{article}
    \usepackage{fontspec,luacode, xcolor}
    \newfontfamily{\arial}{Arial} 
    \begin{document}
    \arial

    \begin{luacode}
    if type(tex)=='table' then local print = tex.print  end

    local patientVisit = {
        patientClass = "CON",
        assignedPatientLocation = {
            pointOfCare = "8152879"
        },
        visitNumber = {
            idNumber = 16164813
        }
     }

    function inspect_table (tab, offset)
        offset = offset or "\\mbox{~~}"
        for k, v in pairs (tab) do
            local newoffset = offset .. offset
            if type(v) == "table" then
               print(offset..k .. " = \\{\\par ")
               inspect_table(v, newoffset)
               print(offset.."\\}\\par")
            else
             if k=="patientClass" then print(offset .. '{\\color{red}'.. k .. "} = " .. tostring(v), "\\par") 
               else
                  print(offset..k.."="..v.."\\par")
               end
           end
        end
    end

    inspect_table(patientVisit)
    \end{luacode}

The routine above is very simple, however it can easily be modified to color code better, sort the fields and add notes etc. As a bonus no need of any catcodes. If you interested in a json solution drop a message and I will post one.

Answer 2

An Example: find it at http://ddi.uni-wuppertal.de/material/materialsammlung/

package is on CTAN: http://ctan.org/pkg/schule

\documentclass{schulein}
\usepackage[utf8]{inputenc}
\usepackage{schulinf}

\begin{document}

\begin{tikzpicture}[syntaxdiagramm]
\node [] {};
\node [terminal] {public};
\node [terminal] {class};
\node [nonterminal] {Klassenname};
\node [terminal] {\{};
\node (endstart) [point] {};
\node [point, below=of endstart] {};
\node [point, xshift=-75mm] {};
\node (endAttribute) [endpoint, continue chain=going below] {};
\node (startAttribute) [point] {};
{[start chain=attribute going right]
    \chainin (startAttribute);
    \node [point, xshift=25mm] {};
    \node [point, continue chain=going above] {};
    \node [nonterminal, continue chain=going left] {Attribut};
    \node [point, join,join=with endAttribute] {};
}

\node (startKonstruktor) [point] {};
\node (endKonstruktor) [endpoint] {};
{[start chain=konstruktor going right]
    \chainin (startKonstruktor);
    \node [point, xshift=30mm] {};
    \node [point, continue chain=going below] {};
    \node [nonterminal, continue chain=going left] {Konstruktor};
    \node [point, join,join=with endKonstruktor] {};
}

\node (endMethode) [endpoint] {};
\node (startMethode) [point] {};
{[start chain=methode going right]
    \chainin (startMethode);
    \node [point, xshift=25mm] {};
    \node [point, continue chain=going above] {};
    \node [nonterminal, continue chain=going left] {Methode};
    \node [point, join,join=with endMethode] {};
}

\node [point] {};
\node [terminal, continue chain=going left] {\}};

\end{tikzpicture}
\end{document}