SAML allows your users to be authenticated and authorized without direct interaction with your web site. It does this by creating a trust relationship between the site and a trusted third party who vouches for the identity of the user. This article explains both how this happens and what the additional benefits are.
What is Kerberos? It is an authentication mechanism which involves three parties (it takes its name from the mythical creature that had three heads for this reason). Kerberos is a ticket based security protocol.
Some Key Concepts Authentication This is the act of verifying you are who you say you are by checking your login credentials.
Authorization This is the act of verifying that you have sufficient rights to access the system....
If you are using Kerberos for single sign-on SSO and want to be able to make http requests impersonating the end user to third party systems you can do this using the HttpClient that is part of the Apache HttpComponents project.