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Open source Java projects: Vert.x

Enterprise messaging and integration with Vert.x

By Steven Haines, JavaWorld.com, 07/30/13

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Page 2 of 6

Figure 1. Architecture of a Vert.x system (click to enlarge)

Vert.x core services and modules

Vert.x functionality can be divided into two categories: core services and modules. Core services are services that can be directly called from a verticle and include clients and servers for TCP/SSL, HTTP, and web sockets; services to access the Vert.x event bus; timers, buffers, flow control, file system access, shared maps and sets, logging, access configuration, SockJS servers, and deploying and undeploying verticles. Core services are fairly static and not expected to change, so all other functionality is provided by modules.

Vert.x applications and resources can easily be packaged into modules and shared via the Vert.x public module repository. Interacting with modules is asynchronous via the Vert.x event bus: send a module a message in JSON and your application will receive a response. This decoupling between modules and integration through the service bus means that modules can be written in any supported language and used by any other supported language. So, if someone writes a module in Ruby that you want to use in your Java application, nothing is stopping you from doing it!

More articles in the Open source Java projects series

Write a Java-based Vert.x web server

We'll start getting to know Vert.x by setting up an environment that we can use to develop our two examples for this article: a basic web server application and a message-passing system. First download Vert.x; as of this writing the latest version is 2.0.0.final. Decompress it locally and add its bin folder to your PATH. Note that you will need to install Java 7 if you haven't already.

If you're a Maven person like me, then you can simply add the following dependencies to your POM file:

Listing 1. Maven POM for Vert.x

 

   <dependency>
        <groupId>io.vertx</groupId>
        <artifactId>vertx-core</artifactId>
        <version>2.0.0-final</version>
        </dependency>
        <dependency>
          <groupId>io.vertx</groupId>
          <artifactId>vertx-platform</artifactId>
          <version>2.0.0-final</version>
        </dependency>

Vert.x's "Hello, World" application is a web server, a good starter application for getting to know Vert.x's event-based programming model. The in-house Vert.x tutorial demonstrates how to create a web server that serves content from a directory called webroot with just a few lines of code. I've written a Java-based variation on the demo as an introductory exercise.

Listing 2 shows the contents of my Server.java file, which is very similar to the one found on the Vert.x homepage. Download the source code for this article to see the complete file.

Listing 2. Server.java

package com.geekcap.vertxexamples;

import org.vertx.java.core.Handler;
import org.vertx.java.core.http.HttpServerRequest;
import org.vertx.java.deploy.Verticle;

public class Server extends Verticle {
    public void start() {
        vertx.createHttpServer().requestHandler(new Handler<HttpServerRequest>() {
            public void handle(HttpServerRequest req) {
                String file = req.path.equals("/") ? "index.html" : req.path;
                req.response.sendFile("webroot/" + file);
            }
        }).listen(8080);
    }
}

The first few lines in Listing 2 import the required Vert.x classes:

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