Introducing the New Data Replication Protocol in Couchbase Mobile 2.0

Couchbase Mobile 2.0 introduces a new replication protocol that enhances data synchronization between clients using Couchbase Lite and the server's Sync Gateway, aiming for a more consistent view of data across local and remote databases. This updated protocol is implemented over WebSockets, offering a cleaner, faster, and more resource-efficient solution than the previous REST-based approach. The new architecture, invented by Jens Alfke, allows for full-duplex message passing, multiplexing, and request/response support, leading to reduced bandwidth and socket resource usage, which can support more concurrent connections. The replication process involves synchronizing database changes using a sequence of messages that track changes via unique sequence IDs, checkpoints, and revision histories, while automatically handling conflicts through a conflict resolver callback. The system ensures persistent connectivity through an exponential backoff algorithm for reconnections and employs heartbeat messages to detect lost connections. This streamlined protocol simplifies peer-to-peer replication and enhances the overall reliability of data synchronization in distributed systems.