What is gRPC?

Learn the main advantages of gRPC and protobuf.

What is gRPC?

gRPC is a remote procedure call (RPC) framework developed by Google. A client calls a function on the server as if it were local. It uses HTTP/2 for transport and Protocol Buffers for data, so its messages are smaller and faster than JSON-based REST.

// on the client side
resp, err := client.Selam(ctx, &pb.SelamIstek{Ad: "Ada"})

Four call types

gRPC offers four communication styles: unary (one request, one response), server streaming (one request, many responses), client streaming (many requests, one response) and bidirectional streaming. It is common for internal communication between microservices; using it directly from a browser needs an extra layer such as gRPC-Web.

Exercise Simulating RPC

Imitate the essence of a gRPC call: type SelamServer struct{} with a method func (SelamServer) Selam(ad string) string returning "Merhaba " + ad. In main, print SelamServer{}.Selam("Ada").

Show example solution

package main

import "fmt"

type SelamServer struct{}

func (SelamServer) Selam(ad string) string { return "Merhaba " + ad }

func main() {
    fmt.Println(SelamServer{}.Selam("Ada"))
}

Test yourself

Which transport protocol does gRPC use?
- FTP
- SMTP
- HTTP/2
- HTTP/1.0
Show answer

HTTP/2 — HTTP/2 provides multiple streams and bidirectional streaming over one connection; gRPC is built on it.

Data format

// selam.proto
syntax = "____";

Show answer

// selam.proto
syntax = "proto3";

Call types

Unary

1 request, 1 response
Server streaming

1 request, many responses
Client streaming

Many requests, 1 response
Bidirectional

Two-way stream

Next lesson: Protobuf definition

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