google play in-app purchase notification for pub/sub topic

Question

I'm trying to implement the backend of payment processor with google play in-app billing.
Google play billing api is tottally built for serveless scenario and is being a hell of a work to make it work for a normal world situation where apps have backends that need to validate and process payment logic.

i'm following this tutorial: https://developer.android.com/google/play/billing/getting-ready#configure-rtdn

but only after implementing the whole logic i read the small line

Real-time developer notifications (RTDN) is a mechanism to receive notifications from Google whenever there is a change in a user's entitlement within your app. RTDN leverages the use of Google Cloud Pub/Sub, which allows you to receive data that is either pushed to a URL that you set or is polled using a client library. These notifications allow you to react immediately to subscription state changes, avoiding the need to poll the Google Play Developer API. Note that inefficient use of the Google Play Developer API can lead to API quota restrictions.

so my logic integration is well done, the test message in play console works but google play billing is not sending the real notifications because my app deals with in-app products and not with subscriptions

then i read this tutorial https://developer.android.com/google/play/billing/rtdn-reference and it says

Note: A OneTimePurchaseNotification is sent only for some types of one-time purchases. For more information, see Integrate.

but the link that was: https://developer.android.com/google/play/integrate goes to 404

does anyone know how to make google play console send notification for payment status on in-app purchases?

also how to get notifications for refunded purchases

Answer 1

OneTimeProductNotification was introduced in 2019-05-07 and its main purpose of handling cash purchases

https://developer.android.google.cn/google/play/billing/release-notes#release-2_0

As release notes says: "This notification type is sent only for purchases associated with delayed forms of payment, such as cash"