Bevezetés a gRPC használatába

Élet a SOAP és a REST után

Márk Sági-Kazár

2023-03-22 @ HWSW meetup

`whoami`

Márk Sági-Kazár

Engineering Technical Lead @ Cisco

@sagikazarmark

https://sagikazarmark.hu

Agenda

About RPC
RPC vs REST
Introduction to gRPC
Implementing a gRPC service
Advanced features
When to use gRPC?
Alternatives

Code samples

https://github.com/sagikazarmark/grpc-intro-workshop

About RPC

Definition 🤔

[…] a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared network), which is coded as if it were a normal (local) procedure call, without the programmer explicitly coding the details for the remote interaction

Wikipedia

Definition

in a different address space → someone else’s computer
normal (local) procedure call → interface
no details for the remote interaction → implementation

Interface Definition Language

a language for describing communication
programming language agnostic
serves as a contract for RPC APIs

RPC vs REST

	RPC	REST
Operates on	procedures (“function calls”)	resources
Underlying protocol	unspecified	primarily HTTP
Interactions	protocol encapsulated	HTTP is part of the contract

RPC is more suitable for APIs describing actions (vs resources)
RPC has better type-safety guarantees
RPC is more strict
REST may be more performant when operating on large amount of data

RPC example in HTTP

POST /sayHello HTTP/1.1
Host: api.example.com
Content-Type: application/json

{
  "userId": 1
}

REST example

GET /users/1/greeting HTTP/1.1
Host: api.example.com

Introduction to gRPC

About gRPC

High performance
Language agnostic (supported languages)
Uses http/2 transport
Bi-directional streaming
Pluggable auth, tracing, load balancing and health checking

IDL: Protocol Buffers

Interface Definition Language
Message format (binary serialization)
Code generation framework

Example 1: Protocol Buffers

Implementing a gRPC service

Example 2: Service definition and server implementation

Example 3: Using the client stub

RPC lifecycle

Unary RPC
Server streaming RPC
Client streaming RPC
Bidirectional streaming RPC

Example 4: Server streaming RPC

Advanced features

Example 5: Authentication and error handling

Interceptors

Act as middlewares during the request lifecycle
Server vs Client
Unary vs Stream

Example 6: Server unary interceptor

When to use gRPC?

With great power comes great responsibility

API operates on actions instead of resources
When efficient communication is a goal
In polyglot environments
No need for supporting a wide range of clients
Internal APIs

whisper microservices

gRPC weaknesses

Limited web/browser support
Not human-readable format (more difficult to debug)
Steeper learning curve

Alternatives

Twirp

Developed at Twitch as a lightweight alternative to gRPC.

https://github.com/twitchtv/twirp

Read the announcement blog post.

Connect

A gRPC-compatible framework with an emphasis on browser- and web-compatibility (from the creators of Buf).

https://connect.build/

The End

Any questions?