We have developed an Android chat-app having Java Spring-boot as backend. We are using the Mesibo messaging platform. We need to develop a push notification feature. Also, we cannot use FCM as it is blocked in certain countries. Mesibo has provided a webhook and some events for sending a push notification.
How will I deliver messages to the user when the app is closed on the phone or the user is offline? Also, I am not sure how the backend will receive the event on which callback will be sent to Mesibo?