Presuming your goal is to establish federation between Ping and your application (in order to e.g. externalize authentication or enable single sign-on), your thinking is correct.
The Ping Federate serves as an Identity Provider (IDP) and you can configure it to connect to your SQL server, so that it can authenticate your existing users from there. IDP communicates with other applications which are called Service Providers (SP).
In order to connect to Ping your application therefore needs to be able to act as a SAML 2.0 Service Provider and using Spring SAML is a very good way to enable it to do so.
The typical flow of data between SP and IDP for single sign-on is similar to:
- User accesses SP application which requires authentication
- SP creates an AuthenticationRequest and sends it to IDP (using redirect in user's browser)
- IDP processes the request and authenticates the user
- IDP responds back to SP with an AuthenticationResponse message
- SP processes the response and creates a session for the user based on the included data