Satosa-Saml2 Spid is an intermediary between many SAML2 Service
Providers and many SAML2 Identity Providers. Specifically it allows
traditional Saml2 Service Providers to communicate with
Spid Identity Providers adapting Metadata and AuthnRequest
operations to the Spid technical requirements.
This solution allows us to adopt multiple proxy frontends and backends to adapt and allows to
communicate systems that, due to protocol or specific limitations, traditionally could not interact each other.
Short glossary:

• Frontend, interface of the proxy that is configured as a SAML2 Identity Provider
• Backend, interface of the proxy that is configured as a SAML2 Service Provider
• TargetRouting, a SATOSA microservice for selecting the output backend to reach the endpoint (IdP) selected by the user
• Discovery Service, interface that allows users to select the authentication endpoint