With the introduction of federation protocols into the process of access management, identity information and entitlements can be communicated across security domains, spanning multiple trusted partners. By configuring a circle of trust and defining applications and services as providers in the circle (either identity providers or service providers), users can opt to associate, connect or bind the various identities they have configured locally for these providers. The linked local identities are federated and allow the user to log in to one identity provider site and click through to an affiliated service provider site without having to reauthenticate; in effect, single sign-on (SSO). OpenSSO Enterprise supports several open federation technologies including the Security Access Markup Language (SAML) versions 1 and 2, WS-Federation, and the Liberty Alliance Project Identity Federation Framework (Liberty ID-FF), therefore encouraging an interoperable infrastructure among providers. For more information on federation management, see Core Services and Part III, Federation Management Using OpenSSO Enterprise.