Simple, Secure and Scalable MessagingFor The Cloud Native EraWaldemar Quevedo /

All Things Open / October 2017

@wallyqs

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Agenda

Intro to the NATS project

NATS & NATS Streaming Overview

Demos

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NATS is a simple, high performance open sourcemessaging system for cloud native applications.

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Facts about NATS

Written by Derek Collison in 2010, originally for CloudFoundry

Initial implementation in Ruby, was then rewritten in Go in 2012

Project used in production environments for ~7 years

NATS Server v1.0.0 milestone reached in July 2017 �

Github Organization: https://github.com/nats-io

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NATS is fast

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Stats about NATSNATS Server can process above +11M messages per second (w/ nats-bench)

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Stats about NATSReliable Low Latency Pub Sub!

Source: http://bravenewgeek.com/benchmarking-message-queue-latency/

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NATS ispredictable �

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https://twitter.com/ripienaar/status/905299955077787648

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https://twitter.com/ngduynd/status/907922573521936384

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NATS is simple

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Simplicity in NATS

Plain text protocol with few commands → Simple network clients & API

7MB binary with no dependencies → Small Docker image �

Fire & Forget Pub Sub on top of TCP/IP

| PUB | SUB | UNSUB | CONNECT | INFO | MSG | -ERR | +OK | PING | PONG |

telnet demo.nats.io 4222 Connected to demo.nats.io. INFO {"server_id":"Fzwx2ndlHFg3lvVwwdBRSe","tls_required":false,...,"max_payload":1048576} SUB hello 1 +OK PUB hello 5 world +OK MSG hello 1 5 world

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Basic API: Go Clientpackage main import ( "log" "github.com/nats-io/go-nats" ) func main(){ nc, err := nats.Connect("nats://127.0.0.1:4222") if err != nil { log.Fatalf("Error: %s", err) } done := make(chan struct{}) nc.Subscribe("hello", func(m *nats.Msg){ log.Printf("[Received] %s", string(m.Data)) done <- struct{}{} }) nc.Publish("hello", []byte("world")) <-done }

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Basic API: Ruby Clientrequire 'nats/client' NATS.start do |nc| nc.subscribe("hello") do |msg| puts "[Received] #{msg}" end nc.publish("hello", "world") end

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Basic API: Python Clientawait nc.connect() async def handler(msg): print("[Received] {data}".format( data=msg.data.decode())) # Coroutine based subscriber await nc.subscribe("foo", cb=handler) await nc.publish("foo", "bar")

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Basic API: Node.js Clientvar nats = require('nats').connect(); // Simple Publisher nats.publish('foo', 'Hello World!'); // Simple Subscriber nats.subscribe('foo', function(msg) { console.log('[Received] ' + msg); });

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Basic API: C ClientnatsConnection_Publish(nc,"foo",data,5); natsConnection_Subscribe(&sub,nc,"foo",onMsg, NULL); void onMsg(natsConnection *nc, natsSubscription *sub, natsMsg *msg, void *closure) { printf("[Received] %.*s\n", natsMsg_GetData(msg)); // ... }

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Basic API: C# Clientusing NATS.Client; ConnectionFactory cf = new ConnectionFactory(); IConnection c = cf.CreateConnection(); ISyncSubscription sSync = c.SubscribeSync("hello"); // Wait up to 1000 ms for next message Msg m = sSync.NextMessage(1000); c.Publish("hello", Encoding.UTF8.GetBytes("world"));

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Basic API: Java ClientConnection nc = Nats.connect(); nc.subscribe("foo", m -> { System.out.printf("Received a message: %s\n", new String(m.getData())); }); nc.publish("foo", "Hello World".getBytes());

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Clients of�cially supported by the NATS team �

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NATS is resilient

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Protection against Slow Consumerspackage main import ( "log" "github.com/nats-io/go-nats" ) func main(){ nc, err := nats.Connect("nats://127.0.0.1:4222") if err != nil { log.Fatalf("Error: %s", err) } n := 0 total := 1000000000 done := make(chan struct{}) nc.Subscribe("hello", func(m *nats.Msg){ n++ if n == total { close(done) } }) for i := 0; i < total; i++ { nc.Publish("hello", []byte("world")) } select { case <-done: } }

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Protection against Slow ConsumersServer disconnects client with Slow Consumer error

Client was too slow at processing the received messages.

[33682] 2017/10/19 07:52:51.647917 [INF] Starting nats-server version 0.9.6 [33682] 2017/10/19 07:52:51.648085 [INF] Starting http monitor on 0.0.0.0:8222 [33682] 2017/10/19 07:52:51.648631 [INF] Listening for client connections on 0.0.0.0:4222 [33682] 2017/10/19 07:52:51.648691 [INF] Server is ready [33682] 2017/10/19 07:52:55.376292 [INF] 127.0.0.1:63184 - cid:1 - Slow Consumer Detected [33682] 2017/10/19 07:52:57.424381 [INF] 127.0.0.1:63185 - cid:2 - Slow Consumer Detected [33682] 2017/10/19 07:52:59.478090 [INF] 127.0.0.1:63186 - cid:3 - Slow Consumer Detected [33682] 2017/10/19 07:53:01.541496 [INF] 127.0.0.1:63188 - cid:4 - Slow Consumer Detected

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NATS Server ClusterHigh Availability via full-mesh cluster topology

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NATS Server ClusterHigh Availability via full-mesh cluster topology

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NATS & Delivery Guarantees

The NATS Server is �re & forget, providing at-most once delivery.

This means that if the consumer is not connected it will not receive the message!

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Is NATS a Message Broker/Queue?From the book (Kleppmann, O'Reilly)

"a message broker (also known as a message queue), is essentially a kind of databasethat is optimized for handling message streams."

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Designing Data-Intensive Applications

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Is NATS a Message Broker/Queue?From the book (Kleppmann, O'Reilly)

"By centralizing the data in the broker, these systems can more easily tolerate clientsthat come and go (connect, disconnect, and crash)

"the question of durability is moved to the broker instead

❌　

Designing Data-Intensive Applications

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Is NATS a Message Broker/Queue?From the book (Kleppmann, O'Reilly)

"Faced with slow consumers, they generally allow unbounded queueing (as opposed todropping messages or backpressure)

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Designing Data-Intensive Applications

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The NATS Server does none of that!

It's the total opposite.

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NATS Streaming

codename: STAN

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NATS Streaming

Supports at-least-once delivery model and durability of messages

Rate limiting & message redelivery features

First release in 2016

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NATS Streaming: How it worksDesigned as a request/response protocol which uses NATS as its transport.

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NATS Streaming: How it worksDesigned as a request/response protocol which uses NATS as its transport.

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NATS Streaming: How it worksDesigned as a request/response protocol which uses NATS as its transport.

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NATS Streaming: How it worksDesigned as a request/response protocol which uses NATS as its transport.

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NATS Streaming ClusteringClustering support in the works!

To be fair, you have to have a very high IQ to understand Rick & Morty clustering

https://github.com/nats-io/nats-streaming-server/issues/316

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NATS Streaming: Go ClientPublish and persist a message

Start with last received message

Receive all messages

sc, _ := stan.Connect(clusterID, clientID) sc.Publish("foo", []byte("Hello World"))

sub, err := sc.Subscribe("foo", func(m *stan.Msg) { fmt.Printf("Received a message: %s\n", string(m.Data)) })

sub, err := sc.Subscribe("foo", func(m *stan.Msg) { fmt.Printf("Received a message: %s\n", string(m.Data)) }, stan.DeliverAllAvailable())

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NATS Streaming: Ruby Clientrequire 'stan/client' sc = STAN::Client.new # Customize connection to NATS opts = { servers: ["nats://127.0.0.1:4222"] } sc.connect("test-cluster", "client-123", nats: opts) # Simple async subscriber sub = sc.subscribe("foo", start_at: :first) do |msg| puts "Received a message (seq=#{msg.seq}): #{msg.data}" end # Synchronous Publisher, does not return until an ack # has been received from NATS Streaming. sc.publish("foo", "hello world")

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NATS Streaming: Python Clientnc = NATS() await nc.connect(io_loop=loop) sc = STAN() await sc.connect("test-cluster", "client-123", nats=nc) await sc.publish("hi", b'hello') async def cb(msg): print("Received a message (seq={}): {}".format(msg.seq, msg.data)) # Subscribe to get all messages since beginning. sub = await sc.subscribe("hi", start_at='first', cb=cb) await sub.unsubscribe()

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NATS Streaming: Node.js Clientvar stan = require('node-nats-streaming').connect('test-cluster', 'test'); stan.on('connect', function () { stan.publish('hello', 'world', function(err, guid){ /*...*/ }); var opts = stan.subscriptionOptions().setStartWithLastReceived(); var subscription = stan.subscribe('hello', opts); subscription.on('message', function (msg) { console.log('Received [' + msg.getSequence() + '] ' + msg.getData()); }); });

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NATS Streaming: Java ClientStreamingConnectionFactory cf = new StreamingConnectionFactory("test-cluster", "bar"); StreamingConnection sc = cf.createConnection(); sc.publish("foo", "Hello World".getBytes()); Subscription sub = sc.subscribe("foo", new MessageHandler() { public void onMessage(Message m) { System.out.printf("Received a message: %s\n", new String(m.getData())); doneSignal.countDown(); } }, new SubscriptionOptions.Builder().deliverAllAvailable().build());

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NATS Streaming: C# Clientvar cf = new StanConnectionFactory(); using (var c = cf.CreateConnection("test-cluster", "appname")) { using (c.Subscribe("foo", (obj, args) => { Console.WriteLine( System.Text.Encoding.UTF8.GetString(args.Message.Data)); })) { c.Publish("foo", System.Text.Encoding.UTF8.GetBytes("hello")); } }

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Also of�cially supported by the NATS team �

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Remember: There are 2 servers

NATS Server / gnatsd

NATS Streaming Server / nats-streaming-server

NATS Streaming itself uses the NATS Server: Two birds, one stone

https://github.com/nats-io/gnatsd

https://github.com/nats-io/nats-streaming-server

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Demos

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Congrats!Now you're ready to start using

/ github.com/nats-io @nats_io

https://nats.io/

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