In runtime the mapping metadata is accessed via a DataChannel in a form of `org.apache.cayenne.map.EntityResolver` (EntityResolver available via ObjectContext is usually obtained from the channel behind the scenes). EntityResolver provides a single namespace for multiple DataMaps.

Another important function of the EntityResolver is providing access to the `org.apache.cayenne.property.ClassDescriptor` instances for each persistent entity. Those a compiled by Cayenne on the fly using EntityResolver's `org.apache.cayenne.property.ClassDescriptorFactory`.