# Package org.eclipse.viatra.addon.validation.core

- Class Summary
  Class | Description
  --- | ---
  Constraint |
  Entry |
  MatchAppearanceJob | The job is used to process new appearing matches upon constraint violation.
  MatchDisappearanceJob | The job is used to process disappeared matches upon constraint violation.
  MatchUpdateJob | The job is used to process updated matches upon constraint violation.
  ValidationEngine | This class uses an `ViatraQueryEngine` for tracking violations of `ConstraintSpecification`s.
  ValidationEngineBuilder | Builder for `ValidationEngine` objects.
  Violation |
  ViolationCreationProcessor | The job is used to process retrieved matches and create violations upon listing on a constraint.