How the Microsoft identity platform uses the SAML protocol
The Microsoft identity platform uses the SAML 2.0 and other protocols to enable applications to provide a single sign-on (SSO) experience to their users. The SSO and Single Sign-Out SAML profiles of Azure Active Directory (Azure AD) explain how SAML assertions, protocols, and bindings are used in the identity provider service.
The SAML protocol requires the identity provider (Microsoft identity platform) and the service provider (the application) to exchange information about themselves.
When an application is registered with Azure AD, the app developer registers federation-related information with Azure AD. This information includes the Redirect URI and Metadata URI of the application.
The Microsoft identity platform uses the cloud service's Metadata URI to retrieve the signing key and the logout URI. In the Azure portal, you can open the app in Azure Active Directory -> App registrations, and then in Manage -> Authentication, you can update the Logout URL. This way the Microsoft identity platform can send the response to the correct URL.
Azure AD exposes tenant-specific and common (tenant-independent) SSO and single sign-out endpoints. These URLs represent addressable locations--they're not just identifiers--so you can go to the endpoint to read the metadata.
The tenant-specific endpoint is located at
https://login.microsoftonline.com/<TenantDomainName>/FederationMetadata/2007-06/FederationMetadata.xml. The <TenantDomainName> placeholder represents a registered domain name or TenantID GUID of an Azure AD tenant. For example, the federation metadata of the contoso.com tenant is at: https://login.microsoftonline.com/contoso.com/FederationMetadata/2007-06/FederationMetadata.xml
The tenant-independent endpoint is located at
https://login.microsoftonline.com/common/FederationMetadata/2007-06/FederationMetadata.xml. In this endpoint address, common appears instead of a tenant domain name or ID.
For information about the federation metadata documents that Azure AD publishes, see Federation Metadata.