With all implementations now being in place, we look forward to how to do node classification.
There are several options available and which one is the best solution mostly depends on your platform.
When you have a very diverse platform, the concept of roles as another abstraction layer is not very useful, as it mostly leads to duplicate code. In this case, most people decided to use profiles for node classification.
When you have large sets of identically configured systems, one wants to go ahead with the role pattern and classify systems by their business use case.
The business use case allows you to describe systems not by what they do, but by what they are used for.
Think about the phpmyadmin installation. Depending on use case and business owner, one might have different classification names:
A technician will use the term database...