The API for specification and processing of constraints in XML.

## Package Specification

The types in this package constitute the provisional API for constraints contributed via XML from plug-in manifests. The {@link org.eclipse.emf.validation.xml.XmlConstraintProvider} is a constraint provider implementation that loads constraint meta-data from the `constraintProviders` extension point into {@link org.eclipse.emf.validation.xml.IXmlConstraintDescriptor}s and uses the {@link org.eclipse.emf.validation.service.ConstraintFactory} to create constraint objects from them.

Dynamic constraint providers may use the API in this package to specify constraints in languages that are supplied to the system by other plug-ins, and use the `ConstraintFactory` to instantiate constraints from these specifications:

- {@link org.eclipse.emf.validation.xml.IXmlConstraintDescriptor}: the meta-data interface for constraints specified in plug-in manifest XML
- {@link org.eclipse.emf.validation.xml.IXmlConstraintParser}: a constraint parser understands a constraint specification (in the form of an `IXmlConstraintDescriptor` in a particular language and can construct an implementation of the {@link org.eclipse.emf.validation.model.IModelConstraint} interface from it
- {@link org.eclipse.emf.validation.xml.XmlConstraintProvider}: the default provider implementation used by plug-ins that specify constraints in the XML. Not generally used in any other way by plug-ins