In this section, let's first consider some common security concerns, and some important concepts associated with them. These concepts are essential for understanding the security model implemented in GlassFish.
Authentication refers to the mechanism by which communicating entities (users, servers, or application components) prove to one another that they are who they claim they are.
Authentication is typically based on authentication realms, or realms for short. A realm typically contains many users (also known as security principals) and their security credentials. Users contained in a realm can be authenticated based on their credentials, such as the username and password. Users defined in a realm may be assigned to groups. Examples of authentication realms include Lightweight Directory Access Protocol (LDAP) servers and relational database tables.