Web applications are vulnerable to security threats because they are exposed to the open world of the Internet. Access to certain Web pages, files, or other classified resources must be restricted to authorized personnel only. Of course, there are several layers of security that are often applied, such as firewall, proxy server, JVM security, and so forth. But, to control access, there must be some security restriction at the application level as well. Therefore, Spring Security, a part of the Spring Framework, is only an advice or provision to apply a level of security at the Java Application stratum
