# Real Time Event Notification API Profile - v3.1.9
The Real Time Event Notification API Profile describes the flows common functionality for the Real Time Event Notification API, which allows ASPSPs to:
- Notify a TPP that an event has occurred.
This profile should be read in conjunction with a compatible Read/Write Data API Profile, a compatible Event Notification API Profile and compatible individual resources.
Implementation of the Real Time Event Notification API is optional for ASPSPs.
The steps and sequence diagram below provide a general outline of an event notification flow for all resources in the R/W APIs.
Step 1: Send Event Notification
- When an event occurs on a resource that requires a notification, the ASPSP identifies the callback-url associated with the TPP owning the affected resource.
- The ASPSP sends a signed event notification to the callback URL, detailing the nature of the event and identifying the affected resource.
- The TPP may optionally initiate a client credential grant to retrieve the resource using the details contained in the event notification.
# Sequence Diagram
participant TPP participant ASPSP Authorisation Server participant ASPSP Resource Server participant ASPSP Notification Service note over TPP, ASPSP Notification Service Step 1: Send Event Notification end note note left of ASPSP Notification Service - Create EventNotification - Sign EventNotification end note loop Retry Until Successful (as per retry policy) ASPSP Notification Service -> TPP: POST /event-notifications, EventNotification, signature alt success TPP -> ASPSP Notification Service: HTTP 202 Accepted else failure TPP -> ASPSP Notification Service: HTTP 500/400 end alt end loop note right of TPP TPP verifies signature end note opt If TPP requires full resource note right of TPP URL for resource contained in the EventNotification rlk (resource links) claim end note TPP <-> ASPSP Authorisation Server: Establish TLS 1.2 MA TPP -> ASPSP Authorisation Server: Initiate Client Credentials Grant ASPSP Authorisation Server -> TPP: access-token TPP <-> ASPSP Resource Server: Establish TLS 1.2 MA TPP -> ASPSP Resource Server: GET Resource ASPSP Resource Server -> TPP: HTTP 200 (OK), Resource end opt option footer=bar