Efficient service-to-service communication.
WHAT IT IS
A framework for calling procedures on another service, using a compact binary format.
WHAT IT USES
An interface definition describing services and messages Generated client and server code A binary encoding
WHAT THAT PROVIDES
Efficiency, in size and speed A strict contract Generated code in many languages Streaming in both directions
WHAT IT SUITS
Communication between internal services High-volume calls Polyglot environments where a shared contract matters
WHAT IT DOES NOT SUIT
Browser clients directly, without a proxy Public APIs for arbitrary consumers
WHY
It is not readable, and not directly callable from a browser or a command line without tooling.
WHAT THE CONTRACT PROVIDES
Types verified at build time on both sides.
WHAT TO BE CAREFUL WITH
Changing message definitions, which must remain compatible Reusing field numbers, which corrupts meaning Debugging, which requires tooling
WHAT TO PLAN
Versioning of the definitions.
WHAT TO COMPARE IT AGAINST
A well-designed REST API, which is frequently sufficient.
