Which method is more commonly used in federated identity environments?

In federated identity environments, SAML (Security Assertion Markup Language) is the most commonly used method. This is primarily because SAML is designed specifically for exchanging authentication and authorization data between parties, specifically between an identity provider (IdP) and a service provider (SP).

SAML allows for Single Sign-On (SSO), which enhances the user experience by enabling users to log in once and gain access to multiple services without needing to log in again each time. This is particularly valuable in federated identity systems where multiple organizations or domains collaborate, as it provides a standard way to handle user identities across different systems while maintaining a secure and consistent authentication method.

While other options like OAuth, OpenID, and WS also facilitate aspects of identity management and authorization, they are either newer, serve different purposes, or are less specific to the federated identity model compared to SAML. OAuth, for instance, is primarily an authorization framework rather than a full identity management solution, while OpenID is more focused on simple user authentication in a non-federated context. WS (Web Services protocols) relate more to service-to-service communication without a primary focus on managing identities in a federated manner.