Spring Security is a widely used security service framework for Java EE-based enterprise applications. At the authentication level, Spring Security provides different kinds of authentication models. Some of these models are provided by third parties, and some sets of authentication features are provided by Spring Security itself. Some of the following authentication mechanisms are provided by Spring Security:

• Form-based authentication
• OpenID authentication
• LDAP specifically used in large environments
• Container-managed authentication
• Custom authentication systems
• JAAS

Let's look at an example to activate Spring Security in a web application. We will use an in-memory configuration.