Netty from the trenches

June 2015@jordi9

Netty…?

Netty is an asynchronous event-driven

network application framework

for rapid development of

maintainable high performance

protocol servers & clients.

Netty is an asynchronous event-driven

network application framework

for rapid development of

maintainable high performance

protocol servers & clients.

Netty is a NIO client server

framework which enables quick and easy development

of network applications such

as protocol servers and clients. It

greatly simplifies and streamlines

network programming such as TCP and UDP

socket server.

OH, MY

The Freaking Basics

You’ve heard of:

Async apps

You’ve heard of:

Event driven frameworks

You’ve heard of:

non-blockingoperations

You’ve heard of:Node is cooler

because...

I/O is everywhere

I/O, approx:

CPU Memory

Device

read()

//wait...

read()

//wait...

keepWorkingBro()

Our programBLOCKS

Resources WASTED

You know what I’m talking

WebserverRequest

Database

//wait...

OH, Parallelism!

new Thread();

WebserverRequest

Database

//wait...

WebserverRequest

Database

//wait...

Request

Database

//wait...

WebserverRequest

Database

//wait...

Request

Database

//wait...

Request

Database

//wait...

A mess

We can do better

read()

keepWorkingBro()

read()

keepWorkingBro()

//I’m //done!

You (kinda) did this:

Listeners

Guava’s EventBus

Javascript callbacks

Hollywood principle

“Don’t call us,we’ll call you”

Keep working, instead of

waiting

Hi, Async I/O

NIOwith Java

java.nio

since 1.4, 2002java.nio

since 1.7: NIO2more goodies

Hi, Complexity

Netty to the Rescue

Built on top of:

java.nio

Built on top of:

java.net

Dependecy-haters:

Just JDK 1.6+

ONEbig difference

All Netty APIsare async

It’s can be one more tool!

What the hell is Netty for?

Think...

HTTP everywhere

Really BRO?

Maybe, you’re trying to

implement a protocol

Finally, hello Netty!

Netty:

Tool to implement network

applications

Netty:

Both from server and client side

Netty:

NIO everywhere

Why Netty?

Netty has been designed carefully

with the experiences

earned from the implementation of a lot of protocols

such as FTP, SMTP, HTTP, and

various binary and text-based legacy

protocols. As a result, Netty has

succeeded to find a way to achieve

ease of development, performance, stability, and

flexibility without a compromise

succeeded to find a way to achieve

ease of development, performance, stability, and

flexibility without a compromise

succeeded to find a way to achieve...

Ease of development

Performance

Stability

Flexibility

Without a compromise

IT’S TRUE

“Implementing a protocol”

NOT THAT HARD

Most common protocols:

out-of-the-box

Boring Protocols:

Cooler Protocols:

HTTP/2

Cooler Protocols:

Protobuf

Even Protocols:

Memcache

Not only I/O

Powerful Thread model

But, where’s the downside?

Downers:

Constant API changes*

Downers:

Constant API changes*

*For the best

Downers:

Learning curve...

Downers:

Learning curve...

Buy Netty in Action :P

Downers:

Join the mailing list

Downers:

You’ll see how STUPID you are

Downers:

But you’ll learn ALOT ;)

Netty,The Code

Daytime Protocol

TheServer

class SimpleDaytimeHandler extends ChannelInboundHandlerAdapter {

The Hand e

// Handler = Business Logic

The Hand e

// ChannelHandler: handles operations // for that Channel, duh

The Hand e

// Inbound handler: incoming traffic, // dispatch events to next handler// If we have inbound...

The Hand e

// Outbound handler: same, but the // other direction. Yeah, there’s some// flow between Handlers (eg: Pipeline)

The Hand e

// Inbound + Outbound...

The Hand e

// Inbound + Outbound..

// 5.0: DEPRECATED!// [NOTE: Insert a grumpy cat here]

The Hand e

Hand e me hod

@Overridepublic void channelRead( ChannelHandlerContext ctx, Object msg) {

// Will trigger when we receive // some data

Hand e me hod

@Overridepublic void channelActive( ChannelHandlerContext ctx, Object msg) {

// Will a Channel is opened, this // method will be called

Hand e me hod

@Overridepublic void channelActive(ChannelHandlerContext ctx, Object msg) {

String date = DATE_TIME.print(new DateTime()); // Get the date

Hand e wo

String date = DATE_TIME.print(new DateTime()); ctx.writeAndFlush(ByteBufUtil.encodeString( ctx.alloc(), CharBuffer.wrap(date), CharsetUtil.US_ASCII));

Hand e wo

It’s clear, right? :D

Network standard way of

working?byte[]

You said this was fun?

MeetByteBuf

ByteBufUtil

String date = DATE_TIME.print(new DateTime()); ctx.writeAndFlush(ByteBufUtil.encodeString( ctx.alloc(), CharBuffer.wrap(date), CharsetUtil.US_ASCII)); // We need to encode the String

Hand e wo

String date = DATE_TIME.print(new DateTime()); ctx.writeAndFlush(ByteBufUtil.encodeString( ctx.alloc(), CharBuffer.wrap(date), CharsetUtil.US_ASCII)); // We allocate some space // +Netty: Keeps internal pools

Hand e wo

String date = DATE_TIME.print(new DateTime()); ctx.writeAndFlush(ByteBufUtil.encodeString( ctx.alloc(), CharBuffer.wrap(date), CharsetUtil.US_ASCII)); // Write the message // Request to actually flush the data // back to the Channel

Hand e wo

We have our Handler in place

Let’s Bootstrap the server

Ma n asspublic class DaytimeServer { void run() throws Exception { // fun stuff }

public static void main(String[] args) throws Exception { DaytimeServer daytimeServer = new DaytimeServer(); daytimeServer.run(); }

java -jar daytimeserver-fat.jar

un()EventLoopGroup bossGroup = new NioEventLoopGroup();EventLoopGroup workerGroup = new NioEventLoopGroup();

E en LoopG oup

Netty’s way to handle threads

E en LoopG oupEventLoopGroup contains someEventLoops

E en LoopEventLoop

handles manyChannels

About to die BRO?

E en LoopG oup

E en Loop

hannehanne

E en Loop

E en LoopG oup

E en Loop

hannehanne

E en Loop

This immutable assignment is

the key

un()EventLoopGroup bossGroup = new NioEventLoopGroup();EventLoopGroup workerGroup = new NioEventLoopGroup();

// Boss group accepts connections// Work group handles the work

Se e Boo s apServerBootstrap b = new ServerBootstrap(); b.group(bossGroup, workerGroup) .channel(NioServerSocketChannel.class) .localAddress(8080) .option(ChannelOption.SO_BACKLOG, 100)

// We assign both event loops

// We use a ServerSocketChannel// to accept TCP/IP connections// as the RFC says

// Simply bind the local address

// Set some Socket options... why not?// Just remember: This is not handled// by Netty or the JVM, it’s the OS

We’re almost there!

hanne P pe neb.childHandler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel ch) throws Exception { ChannelPipeline p = ch.pipeline(); p.addLast(new LoggingHandler(LogLevel.INFO)); p.addLast(new SimpleDaytimeHandler()); }});

// ChannelPipeline to define your// application workflow

// Append our handlers// ProTip: use LoggingHandler to// understand Netty

// Finally, we add our handler

RUN!b.childHandler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel ch) throws Exception { ChannelPipeline p = ch.pipeline(); p.addLast(new LoggingHandler(LogLevel.INFO)); p.addLast(new SimpleDaytimeHandler()); }});

ChannelFuture f = b.bind().sync();f.channel().closeFuture().sync();

// It works!

.I.A.Futures

ByteBuf APICodecs

TransportsZero-file-copy

We can also create

client code

Real lifeInsights

We’re using Netty for Real-Time Bidding

Boo s ap

Tons o op ons

Don’t be afraid of “low-level”

Ta HTTP

Explore what’s inside Netty

Integrate things you love. In my

case: GUICE

Gu e@InjectDaytimeService(Provider<DaytimeServer> daytimeProvider) {}

b.childHandler(() → { ChannelPipeline p = ch.pipeline(); p.addLast(new LoggingHandler(LogLevel.INFO)); p.addLast(daytimeProvider.get());});

// Inject a Provider<T> and get // instances

But… is Netty FAST?

* Without network latency

Yah but… what volume are you talking about?

+10k QPS

1 node*+3k QPS

*Fou 2.79GHz In e Pen um Xeon P o esso s, 7.5GB RAM

But, is this ALOT or not?

Parse example

http://blog.parse.com/learn/how-we-moved-our-api-from-ruby-to-go-and-saved-our-sanity/

(From Ruby to Go) A year and a half in, at the end of 2012, we had 200 API servers running on m1.xlarge instance types with 24 unicorn workers per instance. This was to serve 3000 requests per second for 60,000 mobile apps

We have 16 nodes! 4x Netty nodes10x Kafka, DNS, the usual suspects…

I KNOW IT’S NOT FAIR,

but it’s good stuff for your ego BRO

Lovely ecosystemlike Ratpack,

or users, with vert.x or akka

It will change the way you program some of your apps

Hello, Async problems

Forget about max onn params

One more thing...

(It’s 5:00 in the morning and I had

to say it)

(did you notice the “Apple

background”?)

JUST KIDDINGIt doesn’ really

matter!

Have fun!

THANKS

ProTip: We’re hiring

#HiddenTrovitTrack@jordi9

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