For a long time JVM developers have been sitting out watching web developers write agile and performant applications with frameworks such as node.js. Fortunately this is no longer the case. Vert.x is a powerful, bleeding edge event-driven application framework for the JVM. It features native support for non-blocking I/O and concurrency. It has a distributed event bus that that allows real-time communication between client and server. In addition to including out-of-the-box modules for easy development, vert.x has a module system that enables code reuse. To be even more cool, vert.x is polyglot, supporting components written in different languages such as Javascript, Ruby, and Python. In this speech I will give an overview of the vert.x framework and some of the caveats that you should be aware of.

1. Development with Vert.x:
an event-driven application
framework for the JVM
David Wu
@wuman
blog.wu-man.com
Taiwan Java User Group (2013/06/29)
1Monday, July 1, 13

2. about.me/wuman
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3. What is Vert.x?
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4. What most people will tell you about Vert.x
• A general-purpose application framework
running on JVM
• Performant: asynchronous APIs, event-driven,
non-blocking, etc.
• Highly scalable but also easy to implement
concurrency
• Polyglot: intermix Java, JS, Ruby, Groovy,
Python, etc.
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5. What I think about Vert.x
• All-in-one framework that allows you to focus
on your application rather than fiddling with
different technologies
• Business friendly Apache License 2.0
• Loose coupling modules that interoperate in a
system
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6. Background on the
C10K Problem
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7. Shift from Threading
to Asynchronous
the story of switching from Apache to Node.js
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8. The inevitable comparison to Node.js
• A single event loop serving a high volume of
connections via an asynchronous
programming model
• Most of the real work are done in a pool of
background threads
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9. Asynchronous Programming Model
vertx.createHttpServer().requestHandler(
new Handler<HttpServerRequest>() {
public void handle(HttpServerRequest request) {
log.info("A request has arrived on the server!");
request.response().end();
}
}
).listen(8080, "localhost");
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10. But there are 3
problems with Node.js
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11. Problems with Node.js
• Well, it’s not Java (and this is a Java User
Group)
• Does not easily scale both vertically and
horizontally
• Single event loop fails when you have CPU-
intensive tasks or 3rd-party blocking APIs
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12. Vert.x to the rescue
• Use all available cores on a single machine
• Horizontally scale out to multiple boxes
• Allow blocking calls to NOT run on an event
loop
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13. Introduction to Vert.x instance and Verticles
Verticle
Verticle
WorkerVerticle
WorkerVerticle
Vert.x instance
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14. Verticles are extremely isolated
• Verticles are isolated with separate class
loaders
• A verticle never gets executed by more than
one thread concurrently
• No race conditions, no deadlocks. You write
your code as single threaded.
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15. What about
communication?
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16. Message Passing via the Event Bus
Verticle
Verticle
Worker
Verticle
Worker
Verticle
Vert.x instance
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17. Very Powerful Event Bus
Verticle
Verticle
WorkerVerticle
Verticle
Verticle
WorkerVerticle
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18. Registering a Message Handler
EventBus eb = vertx.eventBus();
Handler<Message> myHandler = new Handler<Message>() {
public void handle(Message message) {
System.out.println("I received a message " + message.body);
}
};
eb.registerHandler("test.address", myHandler);
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19. Message Types
• Primitives and their boxed types
• String
• org.vertx.java.core.json.JsonObject
• org.vertx.java.core.json.JsonArray
• org.vertx.java.core.buffer.Buffer
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20. Pub/Sub Model
eb.publish("test.address", "hello world");
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21. Point-to-Point Model
eb.send("test.address", "This is a message",
new Handler<Message<String>>() {
public void handle(Message<String> message) {
System.out.println("I received a reply " + message.body);
}
});
EventBus eb = vertx.eventBus();
Handler<Message> myHandler = new Handler<Message>() {
public void handle(Message message) {
System.out.println("I received a message " + message.body);
message.reply("This is a reply");
}
};
eb.registerHandler("test.address", myHandler);
21Monday, July 1, 13

22. Shared Maps and Sets
ConcurrentMap<String, Integer> map = vertx.sharedData().getMap("demo.mymap");
map.put("some-key", 123);
Set<String> set = vertx.sharedData().getSet("demo.myset");
set.add("some-value");
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23. Module System
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24. Writing Verticles
import org.vertx.java.core.Handler;
import org.vertx.java.core.net.NetSocket;
import org.vertx.java.core.streams.Pump;
import org.vertx.java.platform.Verticle;
public class Server extends Verticle {
public void start() {
vertx.createNetServer().connectHandler(new Handler<NetSocket>() {
public void handle(final NetSocket socket) {
Pump.createPump(socket, socket).start();
}
}).listen(1234);
}
}
vertx run Server.java
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25. Deploying Verticles programmatically
// For example - deploy some other verticle
container.deployVerticle("foo.js", new AsyncResultHandler<String>() {
public void handle(AsyncResult<String> deployResult) {
if (deployResult.succeeded()) {
System.out.println(“Yay!”);
} else {
System.out.println(“Error: “ + deployResult.cause());
}
}
});
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26. Modules
• Package verticles into re-usable modules
• Simply a zip file containing module definition,
code, and resources
• Very similar to the module system in Node.js
• Modules can be “zip” artifacts released in
Maven Central
• Vert.x web site maintains a listing of Vert.x
modules
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27. Example Modules
• JDBC, Redis, MongoDB Persistors
• AMQP
• Mailer
• Persistent work queue
• Authentication Manager
• Session Manager
• Web framework
• Language implementations
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28. Programming
Experience
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29. Core APIs
• TCP/SSL servers
and clients
• HTTP/HTTPS
servers and clients
• WebSockets
servers and clients
• SockJS
• EventBus
• Shared Maps and
Sets
• Buffers
• Flow control
• Timers
• Files
• Configuration
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30. Container API
• Deploying and undeploying verticles
• Deploying and undeploying modules
• Logging
• Retrieve verticle configuration
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31. Easy development
• Gradle template
• Maven archetype and plugin
• IDE debugging and testing
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32. What is it good for?
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33. Applications
• Realtime analytics dashboard
• Big data queries and task coordination
• Polyglot integration
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34. Some Pain Points
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35. Real life caveats
• Content assist in IDEs don’t work for busmod APIs
• You often find yourself tracing errors in the busmods,
which can be difficult because the stack trace stops
at message passing
• People writing in other languages often get frustrated
by not being able to use native extensions that they
are already used to.
• Hell of anonymous inner class callbacks and no good
Java flow control libraries
• Java7 only. Doesn’t work on Android.
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36. Conclusion
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37. 37Monday, July 1, 13

38. “Using a bleeding-edge
framework is exciting at first.
Not so much afterwards.”
David Wu
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39. Make it better.
Contribute.
http://vert-x.github.io/
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40. Thank you
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41. Q & A
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