The JSP page performs the remote method call to the enterprise bean, using the user’s credential to establish a secure association between the JSP page and the enterprise bean (as shown in Figure 28–5). The association is implemented as two related security contexts, one in the web server and one in the EJB container.
The EJB container is responsible for enforcing access control on the enterprise bean method. It consults the security policy (derived from the deployment descriptor) associated with the enterprise bean to determine the security roles that are permitted access to the method. For each role, the EJB container uses the security context associated with the call to determine if it can map the caller to the role.
The container’s evaluation stops with an “is authorized” outcome when the container is able to map the caller’s credential to a role. A “not authorized” outcome is reached if the container is unable to map the caller to any of the permitted roles. A “not authorized” result causes an exception to be thrown by the container, and propagated back to the calling JSP page.
If the call is authorized, the container dispatches control to the enterprise bean method. The result of the bean’s execution of the call is returned to the JSP, and ultimately to the user by the web server and the web client.
Read Chapter 29, Securing Java EE Applications for more information on protecting web applications.