How can a custom PHR app gets the notification of a consent request being raised by some HIU

@IntegrationSupport
How will a custom PHR app get the app notification that some HIU has raised say a consent request. We can pull the same through /cm/patients/requests API call, but i was looking at the App notification piece. Say, i want to send notification to the user in the phr app when any HIU initiates a consent request. How will the HIE-CM(sbx) will notify the phr app ?

Is there any callback or registry for that part of PHR app?