security-arch | Security architecture document

I have some experience with spring dependency injection and transaction management but I am new to spring security. When i was reading an article related to spring security, I found that @Configuration annotation is used in an example but there were no bean definitions to be found.

According to my understanding, @Configuration annotation is used in classes which contain bean definitions. I need to know that what does the @Configuration annotation do in this example.

I am trying to setup my application using Spring Security. I haven't used spring security before, and I've read the basic architecture site here: https://spring.io/guides/topicals/spring-security-architecture/. In my use case, I have a remote SSO application that my company uses which sits on a different domain. Each of the pages on the application is protected (minus logout), and for each unauthenticated request, the page should redirect to the remote SSO application's login page, where the user will enter their credentials and authenticate. The SSO application will redirect the user back to the requested page after they successfully log in. My application will then use Spring Security to validate the SSO response, populate user details, and create the proper authorization. Once all of that is done, the user will have access to the page(s).

After reading this: Integrate Single Sign On using Spring Security, I think I understand what I have to do for most of it. However, I'm still unclear as to how to get Spring Security to redirect the application to the SSO application if the request is unauthenticated.

Thanks,

JC