I'm currently using an existing Java Web Application. It uses the authentication and authorisation build into Tomcat. It uses a form which has to be submitted with a username and a password. Very common I think.
The situation is as follows: The application is in an internal network. People do not want to log in specifically to this application. They are logged into the network and are used to Single Sign On. I have the code to get the username and password out based on the HTTP-Header. I can print this on the screen without any problem. I want to use the found password and username to authenticate in Tomcat, without showing a login-form.