As of 4D v18 R4, you can send notifications to your application users. Now with 4D v18 R6, you can start data synchronization with a push notification.
This could be useful, for example, in the case of delivery tracking applications. First, the delivery information is updated in the database, then a notification is sent to the customer. The notification contains a request to synchronize the data, so when the customer consults the record on their smartphone, the data is up to date.