A realm, also called a security policy domain or security domain, is a scope over which the server defines and enforces a common security policy. In practical terms, a realm is a repository where the server stores user and group information.
The Application Server comes preconfigured with three realms: file (the initial default realm), certificate, and admin-realm. It is possible to also set up ldap, solaris, or custom realms. Applications can specify the realm to use in their deployment descriptor. If they do not specify a realm, the Application Server uses its default realm.
In the file realm, the server stores user credentials locally in a file named keyfile. You can use the Admin Console to manage users in the file realm. For more information, see Managing file Realm Users.
In the certificate realm, the server stores user credentials in a certificate database. When using the certificate realm, the server uses certificates with the HTTPS protocol to authenticate Web clients. For more information about certificates, see Introduction to Certificates and SSL.
The admin-realm is also a FileRealm and stores administrator user credentials locally in a file named admin-keyfile. Use the Admin Console to manage users in this realm in the same way you manage users in the file realm. For more information, see Managing file Realm Users.
In the ldap realm the server gets user credentials from a Lightweight Directory Access Protocol (LDAP) server such as the Sun Java System Directory Server. LDAP is a protocol for enabling anyone to locate organizations, individuals, and other resources such as files and devices in a network, whether on the public Internet or on a corporate intranet. Consult your LDAP server documentation for information on managing users and groups in the ldap realm.
In the solaris realm the server gets user credentials from the Solaris operating system. This realm is supported on the Solaris 9 OS and later. Consult your Solaris documentation for information on managing users and groups in the solaris realm.
A custom realm is any other repository of user credentials, such as a relational database or third-party component. For more information, see Creating a Custom Realm.