J2EE supports a variety of authentication mechanisms to ensure secure user access and operations. The supported mechanisms include:

HTTP Basic Authentication: A simple challenge-response mechanism that is part of the HTTP protocol.

Form-Based Authentication: A more user-friendly approach where users submit their credentials via a web form.

Client/Server Mutual Authentication: Also known as two-way SSL authentication, where both the client and server authenticate each other.

Role-Based Authentication: Access control based on user roles, often implemented using declarative security in the deployment descriptor.

These mechanisms are designed to provide a flexible and robust security framework for J2EE applications, allowing developers to choose the most appropriate method for their needs.

References:

The official J2EE specification, which outlines the security model and supported authentication mechanisms.

EC-Council’s Application Security Engineer (CASE) JAVA courses and study guides that align with the J2EE security requirements.

InformIT’s article on J2EE Security, which details the user authentication requirements for J2EE products1.

Oracle’s documentation on securing J2EE applications, which includes information on the J2EE security model2.