The previous OneDrive for Business sync app (Groove.exe) used a polling service to check for changes on a predetermined schedule. The changes are processed in the order they are received. Microsoft 365 has metadata pointers directing it through Microsoft Azure.
OneDrive adds it to the Internal Server Changes Queue.
WNS informs the sync app whenever a change actually happens, eliminating redundant polling and saving on unnecessary computing power. The OneDrive sync app uses Windows Push Notification Services (WNS) to sync files in real time. It helps you understand the logic behind how information flows between applications, how the technologies work together, and how data is secured. This article gives you an overview of how sync works in Microsoft OneDrive.
