In this use case, SSO applies to a single client and multiple back end services.. A user accesses multiple back end servers through a single UI client. The user provides credentials to the UI client, and the client validates them against the SSO server. If the validation is successful, the SSO server issues a Security Assertion Markup Language (SAML) token, which is then used by the UI client to access the different back end servers. The following diagram shows this use case.