start a SAML SSO transaction from the identity provider

Question

Consider this schema https://developers.google.com/google-apps/sso/saml_reference_implementation . User will go to the service provider and from there redirected to the identity provider.
But, In my system the user is on the Identity provider to begin with, and presses a link to go to the Service Provider.
So, My question is there a problem with skipping step 1 to 4 and start directly from 5 (Generate a SAML "response" and send it to the Service Provider).

Answer 1

Yes, this is called Unsolicited Responses in the SAML specs. Also called IDP initiated SSO.

It depends on the IPD and SP you are using if this is supported or not. Generally I recommend against using this. It breaks interoperability between products, opens up for XSRF attacs