Explanation
These API methods enable you to manage session authentication:
aaaLogin -Sent as a POST message, this method logs in a user and opens a session. The message body contains an aaa:User object with the name and password attributes, and the response contains a session token and cookie. If multiple AAA login domains are configured, you must prepend the user's name with apic: domain\\ .
aaaRefresh -Sent as a GET message with no message body or as a POST message with the aaaLogin message body, this method resets the session timer. The response contains a new session token and cookie.
aaaLogout -Sent as a POST message, this method logs out the user and closes the session. The message body contains an aaa:User object with the name attribute. The response contains an empty data structure.
aaaListDomains -Sent as a GET message, this method returns a list of valid AAA login domains. You can send this message without logging in.
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/2-x/rest_cfg/2_1_x/ b_Cisco_APIC_REST_API_Configuration_Guide/ b_Cisco_APIC_REST_API_Configuration_Guide_chapter_01.html