This figure shows a SAML request and response cycle, and shows a user, boxes for relying parties, and a box for the issuing authority. The user or client request first goes to the relying party, which sends a SAML request to its issuing authority. The issuing authority responds with a SAML assertion, which supplies the relying party with the requested security information. Two-way arrows denote the client communication with the relying party (there can be more than one relying party), and also denote the request-response communication between the relying party and issuing authority.
Finally, the box for the issuing authority separates out the assertion layer (SAML) from the transport layer (HTTP, SOAP, and so on) to show that the communication between these layers enables the issuing authority to create and validate assertions.