Vert.x

An event-driven polyglot VM!

By

Siddique Hameed

STLJS (St. Louis JavaScript) Meetup

10/16/2014

Vert.X is...

• Event-Driven aka asynchronous
• NIO (Non-Blocking I/O) based
• Light-weight
• Reactive (See Reactor Pattern - http://en.wikipedia.org/wiki/Reactor_pattern)
• Distributed
• Scalable
• Resilient
• Node like but, not a clone :)
• Isomorphic
• Polygot!
• Extensible...

What do you speak?

Verticles

The smallest unit of code that runs inside a Vert.x instance. Strictly single-threaded.

Many of them can be executed concurrently in different nodes/instances.

Composable units forming pipeline or network of code execution.

Written in a supported programming language of your choice...

var vertx = require('vertx');

vertx.createHttpServer().requestHandler(function(req) {
    req.response.end("Hi there STLJS!");
}).listen(8080, 'localhost');
                        

Modules

Functional encapsulation of verticles.

Typical Vert.x application is composed of one more more modules.

Uses mod.json as module descriptor

Module registry is available at - http://modulereg.vertx.io/

vertx install io.vertx~mod-redis-client~1.1.4
                    

Worker Verticles

Verticles where you can run blocking calls. Remember JDBC ?

Multi-threaded, where you can perform computationally intensive/blocking operations.

Be careful using this, it won't scale!

Async huh?

• JavaScript developers are comfortable with asynchrous style programming due to DOM event handlers, callbacks etc.
• Java & other languages are catching up on this style
• No more single thread for every single request
• Obviously, its easier said than done.
• So, seek help from promise libraries & modules like mod-rx-vertx which uses RxJava library (inspired by .Net's Reactive extensions)

Vert.x instances

• Where the verticles are run...
• A single instance runs inside its own JVM instance
• Instances are clustered within the same host or on different hosts across the network forming a distributed event bus
• Guaranteed that a single instance will not be executed by more than one thread concurrently

Distributed Event Bus

• Nervous system of Vert.x!
• Verticles communicate with each other over the distributed event bus.
• Messaging Models
• Point-to-Point
• Request/Response
• Publish/Subscribe
• Layer transparent!
• Also available at the browser.Think Firebase, Meteor!
• Demo will be coming shortly.

Message Types

• number
• string
• boolean
• JSON object
• Vert.x Buffer

Shared Data (Maps & Sets)

Data structure to share across verticles & modules.

Meant to be immutable!

var map = vertx.getMap('myMap');
map.put('myKey', 'myValue');

var set = vertx.getSet('mySet');
set.add('myValue');

Clusters

Out-of-box clustering support.

Pluggable clustering manager, default is based on Hazelcast

High Availability (HA) mode

Automatic failover support!

Faul tolerant eh...

When a module fails in one node, it will automatically start on another node on the cluster.

    vertx -ha

Demo please...

APIs

• vertx
• vertx/container
• vertx/buffer
• vertx/console
• vertx/datagram
• vertx/dns
• vertx/event_bus
• vertx/file_system
• vertx/http
• vertx/net
• vertx/shared_data
• vertx/sockjs
• vertx/timer
• etc.

Container APIs

• Used for dynamically deploying & un-deploying verticles and modules

/*Deploy 4 instance of verticle.js*/
container.deployVerticle("verticle.js", 4);

Serve what?

• HTTP/HTTPS client & server
• HTTP methods (GET, PUT, POST etc.)
• Supports HTTP chunked transfer encoding
• Multipart
• WebSockets
• SockJS server
• etc.

Demo

Distributed Event Bus

References

• http://www.infoq.com/presentations/performance-reactive-vertx/
• http://vertx.io/manual.html
• http://vertx.io/core_manual_js.html
• https://github.com/vert-x
• https://github.com/vert-x