Be  reactive  on  the  JVM  but  not  only  in  Java

Clement Escoffier, Red Hat

Reactive§Responsiveness§On various workload (elasticity)§ In the face of failures (resilience)

§Message-driven§Asynchronous message-passing

Polyglot§Not only Java§Groovy, Ruby, JavaScript

§Run on top of a JVM

Handler

Event Loop

Handlers

Handlers are alwayscalled in the samethread (the event loop)

Event Loop

Handlers

Handlers must never block the thread callingthem.

Event Loop

Event Loop

Handlers are always executed in the same event loop.

Event Loops

A Message

A Notification

A HTTP Request

A command, an instruction

A file

A result, a report, an error

void operation(param 1,  param2,  Handler<      >  handler)  {

//…handler.handle(      )//…

}

void handle( ) {// do something with

}

vertx.createHttpServer().requestHandler(

req -­‐>  req.response().end("Hello  there!")).listen(8080,

ar -­‐>  {if  (ar.failed())  {System.out.println("The  HTTP  Server  has  failed  to  start");

}  else  {System.out.println("The  HTTP  Server  is  up");

}}

);

void add(int a,  int b,  Handler<Integer>  handler)  {int r  =  a  +  b;handler.handle(r);

}

void doSomething()  {add(1,  1,  i -­‐>  {

System.out.println("result  :  " +  i);

});//…

}

2

13

Event Bus

Point to PointPublish / SubscribeRequest / Response

Event Bus

Messages are received using Handlers and delivered using the event loop.

Event Bus

Each vert.x instance has access to the event bus.

Event Bus

The event bus allows distributed communication.

Machine 1

Machine 2Machine 3

Almost anything can send / receive messages

Machine 1

Machine 2Machine 3

binnode

Verticles are chunks of code that get deployed and run by Vert.x.

Verticle

Event Bus

Handler

vertx.deployVerticle("my.verticle");

Verticles have a lifecycle (start, stop)

Verticle

Event Bus

Handler

Verticles interact using events / messages.

Verticle

Event Bus

Handler

Verticles can be instantiated multiple times.

vertx.deployVerticle("my.verticle",  new  DeploymentOptions()

.setInstances(3));

Dead verticles are restarted on a running node.

Verticlesfail-over

vertx.deployVerticle("my.verticle", new DeploymentOptions()

.setHA(true));

Verticles can be written in any supported language

GroovyVerticle

JSVerticle

JavaVerticle

RubyVerticle

Polyglot

Event BusDistributed

Verticle

puts  "Hello"

EventsEvent Loops

Handlers

Core

WebAuth

JDBC Redis

Mongo

Stomp

Mail JCA RX

Metrics

JS Client

Docker

OpenShift

Shell

Sync

SvcSvc

Svc

Micro-services interact using the event bus

Packaged in a fat jar

SvcSvc

Svc

HTTP /REST

TCP

or using HTTP, TCP, STOMP, AMQP

SvcSvc

Svc

Proxy generation for the event bus

Service exposed on the event busClient

SvcSvc Consumption of services

from node.js or the browser

JavaScriptClient

JS

SvcSvc

Svc

Each service scales up and down, and supports fail-over

HTTP /REST

http://vertx.io

http://vertx.io/blog/my-first-vert-x-3-application

https://github.com/vert-x3/vertx-examples