What gRPC Is

Contract first, code generated

gRPC is an open-source remote procedure call framework, originally developed at Google and now a CNCF project. You define services and messages in a .proto file; tools generate a client stub and a server interface in many languages (Go, Java, C++, Python, C#, Node.js, Kotlin, Swift, Rust and others). The client calls a method such as GetOrder(request) and the framework serialises the request, sends it, and returns a typed response, so polyglot services share one contract.

Calling remote functions efficiently

gRPC lets services call each other's methods as if they were local, using a typed contract and an efficient transport.

A phone extension directory

Instead of writing a letter in any format (a free-form HTTP request), you dial a known extension and follow an agreed script; both sides know exactly what will be said.

Treat .proto files as the API

Review, version and publish proto files like any public interface; generated code follows from them.

Quick check: What does a gRPC client call?

• SQL stored procedures
• Arbitrary URLs with free-form JSON
• Generated stub methods defined in the .proto service
• Shell commands on the server