[jboss-jira] [JBoss JIRA] (JBRULES-3585) Drools Planner should support JSR-331 too (for those that prefer math equations as constraints over object-orientated constraints)

[Geoffrey De Smet (JIRA)]

Geoffrey De Smet created JBRULES-3585:
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             Summary: Drools Planner should support JSR-331 too (for those that prefer math equations as constraints over object-orientated constraints)
                 Key: JBRULES-3585
                 URL: https://issues.jboss.org/browse/JBRULES-3585
             Project: Drools
          Issue Type: Feature Request
      Security Level: Public (Everyone can see)
          Components: drools-planner
            Reporter: Geoffrey De Smet
            Priority: Minor


JSR-331 is a constraint programming standardization effort and we could create a drools-planner-jsr331 to bridge that API.
- Such a module shouldn't pose to many technical difficulties (it's basically translating the math equations in primitive based rules)
- Such a module is a lot of effort none-the less. There need to be enough users actually wanting to use JSR 331.

Personally, I doubt many users would prefer math equations to write their constraints (vote on this issue to prove me wrong). Here's an example why:

In Drools scoreDRL you say something like this:
{code}
// Dependency constraints: each process of a service must have at least one process of it's depended services running in it's neighborhood
rule "serviceDependency"
    when
        $serviceDependency : MrServiceDependency($fromService : fromService, $toService : toService)
        $processAssignment : MrProcessAssignment(service == $fromService, $neighborhood : neighborhood)
        not MrProcessAssignment(service == $toService, neighborhood == $neighborhood)
    then
        // Constraint broken
end
{code}

In a Java ScoreDirector, you say something like this:
{code}
// Dependency constraints: each process of a service must have at least one process of it's depended services running in it's neighborhood
for (MrServiceDependency serviceDependency : serviceDependencyList) { // TODO use Maps
   for (MrProcessAssignment processAssignment : serviceToProcessAssignmentMap.get(serviceDependency.getFromService()) {
       if (!neighborhoodToServiceListMap.get(processAssignment.getNeighborhood()).contains(serviceDependency.toService()) {
           // Constraint broken
       }
   }
}

In JSR-331, which doesn't support Object-Orientation in it's constraints, this wouldn't look good.

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