It seems the sanest way (from a human perspective) of modelling an OPC-UA server is to create a (relatively) simple XML file describing data and relations (the "model design" format), convert it into another more machine-oriented XML file (the "NodeSet2" format) and then generate from it the C code to be linked against other server code.
The conversion from model design to NodeSet2 is performed by
UA-ModelCompiler, a tool
officially endorsed by the OPC foundation, while the generation of the C code
from NodeSet2 is performed by nodeset_compiler.py, a Python script provided
by the awesome Open62541 project.
While nodeset_compiler.py, apart from being included in PATH, does not
require any particular processing, the UA-ModelCompiler is strongly geared
towards Windows/DotNet and it is in general quite unpleasant to work with.
In other words, compiling model designs on GNU/Linux systems is a nightmare.
The only documentation I found is the OPC-UA information model tutorial, which provides a strong foundation for understanding the whole process but the commands reported there for converting the model design simply do not work on my system (ArchLinux current).
After a lot of trials and errors, I came up with a solution based on docker
that does not require building and installing UA-ModelCompiler natively.
See the Makefile for the gory details.
The sample model design used here is an adaptation of the work done by Industry40tv on its YouTube tutorial: check it out for a really good introduction.
