You can define additional repositories
as required for the out-of-box federated repositories user registry.
For example, you can define one or more databases and/or LDAP directories
for the user registry. Federated repositories also let you implement
multiple realms. Realms define subsets of users and are spread across
multiple repositories. For example, you can define one realm in a
file-based repository and another realm in an LDAP directory. Because WebSphere® Application
Server provides an implementation
of the UserRegistry interface for federated repositories
out-of-box, you do not need to create a custom implementation of this
interface.