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Vert.x core examples

Here you will find examples demonstrating Vert.x core in action.

Vert.x core provides fairly low level functionality for a diverse range of functions including HTTP, TCP, UDP, WebSockets, file system access, timers, verticles and more. Please consult the Vert.x core manual for detailed documentation on Vert.x core.

Examples can be run directly from the IDE by executing the main method.

Dependencies required

To use Vert.x core in your own Maven or Gradle project add the following dependency

Group ID: io.vertx
Artifact ID: vertx-core

Embedding

Vert.x core can be embedded in any Java class and run that way if you like.

The Java embedded example shows an example of that. Just right-click the class in your IDE to run it directly.

Net examples

These examples demonstrate usage of Vert.x net servers and clients - these are used for TCP (and SSL) servers and clients.

Echo

This example consists of an echo server verticle which serves TCP connections, and simply echoes back on the connection whatever it receives.

You can run the echo server then run telnet localhost 1234 from a console to connect to it. Type some stuff and see it echoed back to you.

It also contains an echo client, which creates a connection to the server, sends some data and logs out what it receives back. You can use that as an alternative to connecting via telnet.

Echo SSL

This is the same as the Echo example but using SSL to encrypt connections

HTTP examples

These examples demonstrate usage of HTTP with Vert.x.

Simple

A very simple HTTP server which always responds with the same response:

You can run the server then open a browser and point it at http://localhost:8080

And a simple HTTP client which makes a request to the server.

HTTPS

Like the simple example, but using HTTPS instead of HTTP

You can run the server then open a browser and point it at http://localhost:4443

And a simple HTTPS client which makes a request to the server.

Proxy connect

Connecting to a web server using a proxy. The proxy receives requests and connects to the endpoint server using a socket, then pass all the events between the client and the proxied server.

Proxy

A simple toy HTTP proxy. The proxy receives requests and forwards them to the endpoint server, it also takes responses from the other server and passes them back to the client.

Sendfile

This example demonstrates how you can serve static files from disk using a Vert.x http server.

You can run the server then open a browser and point it at http://localhost:8080

Note
 in practice, you would probably actually use Vert.x-Web for this rather than writing a web server at this low level. Serving files manually like this can leave you open to security exploits, e.g. by clients crafting URI paths which try to access resources outside the permitted area. Vert.x-Web provides URI path normalisation to avoid these kinds of exploits and comes with a static file handler which also handles caching headers and other features that you would probably want when serving static files in a web application.

Simple form

This example demonstrates how you can handle an HTML form on the server.

You can run the server then open a browser and point it at http://localhost:8080

Note
 In practice, you would probably also use Vert.x-Web for this rather than writing a server at this low level. Vert.x-Web provides built in support for HTML forms, and avoids some security issues due to maliciously crafted URI paths.

Simple form file upload

This example demonstrates how you can handle file uploads from an HTML form submission.

You can run the server then open a browser and point it at http://localhost:8080

Note
 In practice, you would probably also use Vert.x-Web for this rather than writing a server at this low level. Vert.x-Web provides built in support for HTML forms and file uploads, and avoids some security issues due to maliciously crafted URI paths.

Http request body upload

This examples demonstrates an HTTP server receiving a request and piping the request body to a file on disk without ever storing the entire request body fully in memory.

There’s also a client which sends a request to the server and pipes a file from disk to the HTTP request body. The file is uploaded successfully even if the file is very large (GigaBytes).

HTTP Server Sharing

A server that illustrates the round-robin orchestrated by vert.x when several verticles are opening HTTP servers on the same port:

The Server deploys two instances of the HttpServerVerticle verticle.

You can run the server then open a browser and point it at link:http://localhost:8080. Requests will be handled by an instance after the other.

The Client illustrates the round-robin by periodically requesting the server and displays the response content.

WebSockets echo example

This example shows a Vert.x HTTP server which handles websockets connections. This example simply echoes back to the client whatever it receives on the websocket.

There’s also a client which connects to the server, sends some data and logs out what it receives.

You can run the server then open a browser and point it at http://localhost:8080

Note
 in practice, you would probably use Vert.x-Web to build a web application that uses WebSockets

HTTP/2 examples

These examples demonstrate usage of HTTP/2 with Vert.x.

Simple

A very simple HTTP/2 server which always responds with the same response:

You can run the server then open a browser and point it at http://localhost:8080

And a simple HTTP/2 client which makes a request to the server.

Push

This example shows HTTP/2 push.

The server pushes script.js along with index.html:

You can run the server then open a browser and point it at http://localhost:8080

And a client sets a push handler to be notified of the incoming server side pushes:

H2C

Like the simple server but using clear text, also known as h2c, without TLS:

Note
 this example won’t work with browsers are they don’t support h2c

Custom frames

HTTP/2 can be extended with custom frames, this example shows how to write and receive custom frames:

Event bus examples

These examples demonstrate usage of the event bus in Vert.x

Point to point

This example demonstrates point to point messaging between a receiver and a sender.

The receiver listens on an address on the event bus for incoming messages. When it receives a message it replies to it.

The sender sends a message to that address every second, when it receives a reply it logs it.

Publish / Subscribe

This example demonstrates publish / subscribe messaging between a receivers and a sender. With pub/sub messaging you can have multiple subscribers who all receive messages from publishers.

A receiver listens on an address on the event bus for incoming messages. When it receives a message it logs it.

The sender sends a message to that address every second, when it receives a reply it logs it.

You can start as many senders or receivers as you like.

MessageCodec

This example demonstrates how to write custom MessageCodec for send / publish / receive any type of object. It means you can send or receive custom data type objects directly through EventBus as well as primitive types like String.

In this example, there are two type of receivers. The first one is a local type which is deployed from sender, the other one is a cluster-wide type that launched from another instance of cluster. So you can see how MessageCodec works differently on the local EventBus and clustered EventBus.

You can start as many senders or receivers as you like.

SSL

This example demonstrates point to point messaging between a receiver and a sender with a transport level encryption.

The receiver listens on an address on the event bus for incoming messages. When it receives a message it replies to it.

The sender sends a message to that address every second, when it receives a reply it logs it.

Future

Examples using Vert.x Futures are available in the Future directory.

Verticle examples

These examples show verticles being deployed and undeployed.

Deploy example

This example shows a verticle deploying another verticle in several ways including:

  • Deploying without waiting for it to deploy

  • Deploying and waiting for it to deploy

  • Passing configuration to another verticle during deploy

  • Deploying more than one instance

  • Deploying as a worker verticle

  • Undeploying a verticle deployment explicitly

Asynchronous deployment example

This is similar to the deployment example, but it shows how the start and stop of a verticle can be asynchronous. This is useful if the verticle has some startup or cleanup to do that takes some time, and we wish to avoid blocking the event loop.

Worker Verticle example

A simple example illustrating how worker verticle can be created and the thread switches when interacting with them. The worker verticle is not System.out.println(Thread.currentThread()); ed in the event loop and so can do blocking operations.

Execute blocking example

This example demonstrates how you can include blocking code in with your non-blocking code in a way that doesn’t block an event loop:

Run the example then open a browser and point it at http://localhost:8080

Run the example then open a browser and point it at http://localhost:8080

JSON streaming parser

A simple example illustrating how to use the streaming JsonParser to parse a giant array of small objects.

Custom ReadStream and WriteStream implementation

An example illustrating how to create your custom prefix length protocol to read and write objects in wire. The example uses Batch object, ReadStream and WriteStream implementation.

The protocol structure for Batch object is simple as illustrated below:

Length  : uInt32
Type    : byte ['O' for JsonObject | 'A' for JsonArray | 'B' for Buffer]
Payload : Buffer

The NetServer will receive the objects and write them back to the NetClient.