Replace Class Metadata Configuration with an N3 Rule using Reasoning

[BenjaminHofstetter]

This started in n3-class-metadata

The goal is to:

• Make the configuration simpler
• Make the code simpler
• Make SPARQL Query generation simpler
• Use better semantics inside blueprint

The current configuration is similar to this...

+----------------+
| ClassMetadata  |
|  - icon        |
|  - color       |
|  - label       |
|  - comment     |
|  - searchPrio  |          +----------------------+
| sh:targetNode  |--------->| :Person a rdfs:Class |
+----------------+          +----------------------+

What is wrong with that approach:

• Hard to remember
• This has no semantics
• ...it only has an effect in code
• All instances of this class appear in the UI ... this is a kind of side effect

First Try:
Create an N3 rules for this and use the eye reasoner to add the information directly to the subjects.

  {
    ?s a <https://schema.org/Organization> 
  } => {
    ?s <https://flux.described.at/searchPrio> 3 ;
         <https://flux.described.at/label> "Organization" ;
         <https://flux.described.at/comment> "" .
         <https://flux.described.at/icon> "fa-solid fa-building" ;
         <https://flux.described.at/colorIndex> "1"  ;
     .
  } .

You can read the rule like { if } => { then } .
Then use the rule to "reason" the Icon, Color, SearchPriority, and the "Class" Label.

Findings after the implementation:

• it's possible to migrate the old "sh:targetNode" to n3 rules ... so no hard migration needed
• eye is a bit slow. It took 700ms inside eye reasoning for 16 rules.
• for simple rules with exactly this pattern I did my own implementation for this. It takes 4ms
• the structure isn't good enough. We have cases where a subject has two icons, and two colors and two labels.

Second try:

  {
    ?s a <https://schema.org/Organization> 
  } => {
    ?s <https://flux.described.at/searchPrio> 3 ;
         <https://flux.described.at/label> "Organization" ;
         <https://flux.described.at/comment> "" .
         <https://flux.described.at/icon> "fa-solid fa-building" ;
         <https://flux.described.at/colorIndex> "1"  ;
     .
  } .