The Evolution of the RPC Interface: From JSON to REST

For years, the JSON-RPC interface was the only way to talk to Bitcoin Core. It is a "Request-Response" model.

• The Problem: If you want to monitor blocks in real-time, you have to "Poll" the node every second, which is wasteful.

• The Innovation: The REST API: Bitcoin Core now includes a REST interface (rest=1) that allows for much faster, non-authenticated access to non-sensitive data like block headers and the mempool.

• The Future: gRPC: There is an ongoing effort to implement gRPC (Google Remote Procedure Call), which would allow for even faster, typed communication between Bitcoin and other services.