Introductions

Derek Eskens

@snekse

Dev 20+ years, Consulting 8+ years

Java, JS, Groovy

'Foodie for Life' is tattooed across my tummy

Star Wars > Star Trek

gRPC

gRPC Remote Procedure Calls 🙄

What is gRPC

TL;DR

"A high performance, open source universal RPC framework"

Binary Transport over HTTP/2

Really? 🤨 RPC?

CORBA?

RMI?

SOAP?

Didn't we abandon RPC?

Why is gRPC different?

11+ languages
Incredibly fast
Small footprint
(storage, memory, transport)
Simple IDL
Flexible Evolution
BiDi Streaming
Integrated Auth
Generated Client Libraries

What's wrong with REST?

If you want to get technical...

JSON + HTTP Verbs ≠ REST

If you don't HATEOAS, you hate us

What we really mean

So what's wrong with
RESTful-ish

Maybe nothing!

Human Readable
Discoverable
Low Coupling
Low Complexity
curl / Postman
Caching
Easy Versioning?

}

-ish

Where RESTful fails

Chattiness
Schema/Types
Complex Models
Beyond the State Engine
Performance Costs
Common Client Code
Streaming

Choices

Who is your API for?

Public?

Volume?

Message Size?

Streaming?

Polyglot?

CRUD?

Bandwidth?

Devices?

When to consider gRPC

Performance
Cohesion
Bandwidth
Tolerant Versioning
Internal Only Usage
Single Client
??? 🎤

The Obvious

High throughput internal µServices
Streaming content
Real-time Applications
Interacting with Kafka
Programming in Go

The Less Obvious

Mobile Apps

Tolerant Versioning
- App store approvals
- Old App Versions
Client Stubs
- Fast development
Performance
- Weaker CPUs
- Data Caps/Speed
- Save Battery Life

IoT Devices

Constraints
Limitations
Hinderances

Tens of MHz, KBs of Memory

Splitting an Existing Monolith

Why not...?

gRPC vs ...

The Nitty Gritty

HTTP/2

Binary Frames
HPACK Compression
Single Connection
Multiplexing
Server Push
TLS Default
Flow Control

Protobuf

Default IDL
Language Agnostic
Platform Agnostic
Simple
Robust
Fast

Technically gRPC is format agnostic

ns/ops

750

1500

2250

syntax = "proto3";

import "google/protobuf/timestamp.proto";

message StockQuoteRequest {
  string symbol = 1;
}

message Price {
  int32 amount = 1; //Thanks NASDAQ 🙄
}

message BidAsk {
  Price bid = 1;
  Price ask = 2;
}

message StockQuoteResponse {
  string symbol = 1;
  Price last 	= 2;
  BidAsk bidAsk = 3;
  google.protobuf.Timestamp date = 4;
}

A Brief Protobuf Syntax Intro

syntax = "proto3";

import "opi/brokerage/financial-instruments/pricing.proto";

service QuoteService {

    // Get the current price
    rpc GetQuote (StockQuoteRequest) 
    	returns (StockQuoteResponse);

    // Get level II streaming quotes
    rpc GetQuoteStream (StockQuoteRequest) 
    	returns (stream StockQuoteResponse);
}

   protoc

Now admire all of your beautiful stubs

public class QuoteServiceImpl extends QuoteServiceImplBase  {

  @Override
  public void getQuote(StockQuoteRequest req, StreamObserver<StockQuoteResponse> rspObserver) {
    try {
      // Get the quote from a 3rd party provider
      RealTimeQuote rtq = rtQuoteProvider.getRealTimeQuote(req.getSymbol());
      
      // Build our response
      StockQuoteResponse stockQuoteResponse = toResponse(req.getSymbol(), rtq);
      
      // send the response
      rspObserver.onNext(stockQuoteResponse); 
      
    } catch (Exception e) {
      rspObserver.onError(Status.UNKNOWN
        .withDescription("Failed to get quote for " + req.getSymbol())
        .augmentDescription(e.getMessage())
        .asRuntimeException()
      );
    } finally {
      rspObserver.onCompleted(); // mark RPC call as complete
    }
  }

  // ...
}

Implementing the Service

  private StockQuoteResponse toResponse(String ticker, RealTimeQuote rtq) {
    return StockQuoteResponse.newBuilder()
      .setSymbol(ticker)
      .setLast(asPrice(rtq.last))
      .setBidAsk(asBidAsk(rtq.bid, rtq.ask))
      .setDate(getTimestamp())
      .build();
  }
  
  private Price asPrice(int value) {
    return Price.newBuilder().setAmount(value).build();
  }

  private BidAsk asBidAsk(int bid, int ask) {
    return BidAsk.newBuilder()
        .setBid(asPrice(bid))
        .setAsk(asPrice(ask))
        .build();
  }
  
  private Timestamp getTimestamp() {
    // ...
  }