Building Mobile-First Infrastructure for Messenger

Introduced a new mobile-first sync protocol for Messenger, moving from a pull-based model to a push-based snapshot + delta model using MQTT. Replaced JSON with Thrift for message and delta updates, reducing payload size by ~50%. Developed a new server-side service called Iris, which acts as a totally ordered queue of messaging updates, enabling independent synchronization rates for the Messenger app and traditional storage tiers. Implemented a tiered storage model with Iris's memory, backing store, and traditional disk storage.