When a user logs into an application, OpenSSO Enterprise plug-ins retrieve all user information, authentication properties, and authorization policies that the OpenSSO Enterprise framework needs to form a temporary, virtual user identity. The Authentication Service and the Policy Service use this virtual user identity to authenticate the user and enforce the authorization policies, respectively. All user information, authentication properties, and authorization policies is contained within a realm. You create a realm when you want to apply policies to a group of related subjects, services or servers. The Policy Configuration Service within the realm provides a means to specify how policies are defined and evaluated. It enables you to specify, for example, which directory to use for subject lookup, the directory password, which search filters to use, and which subjects, conditions, and response providers to use. For example, you can create a realm that groups all servers and services that are accessed regularly by employees in one region. And, within that regional grouping realm, you can group all servers and services accessed regularly by employees in a specific division such as Human Resources. A configured policy might state that all Human Resources administrators can access the URL http://HR.example.com/HRadmins/index.html. You might also add constraints to this policy: it is applicable only Monday through Friday from 9:00 a.m. through 5:00 p.m. Realms facilitate the delegation of policy management privileges. These configurations can be done within a realm or a sub realm and is accessible using the OpenSSO Enterprise console.
Access control realms can be configured to use any supported user database.