Engine.IO Java

This is the Engine.IO Server Library for Java ported from the JavaScript server.

NOTE This library will follow the major version of the JS library starting with version 4.

See also: Socket.IO-server Java, Engine.IO-client Java

Documentation

Complete documentation can be found here.

Installation

If you're looking for the socket.io library instead, please see here.

The latest artifact is available on Maven Central.

Maven

Add the following dependency to your pom.xml.

<dependencies>
  <dependency>
    <groupId>io.socket</groupId>
    <artifactId>engine.io-server</artifactId>
    <version>6.2.1</version>
  </dependency>
</dependencies>

Gradle

Add it as a gradle dependency in build.gradle.

implementation ('io.socket:engine.io-server:6.2.1')

Engine.IO Protocol 1.x suppport

The current version of engine.io-java does not support protocol 1.x.

Usage

If you're looking for the socket.io library instead, please see here.

Usage is slightly different based on the server being used.

Create a servlet to handle the HTTP requests as follows:

public class EngineIoServlet extends HttpServlet {

    private final EngineIoServer mEngineIoServer = new EngineIoServer();

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
        mEngineIoServer.handleRequest(request, response);
    }
}

Listen for new connections as follows:

EngineIoServer server;  // server instance
server.on("connection", new Emitter.Listener() {
    @Override
    public void call(Object... args) {
        EngineIoSocket socket = (EngineIoSocket) args[0];
        // Do something with socket like store it somewhere
    }
});

Listen for raw packets received as follows:

EngineIoSocket socket;  // socket received in "connection" event

socket.on("packet", new Emitter.Listener() {
    @Override
    public void call(Object... args) {
        Packet packet = (Packet) args[0];
        // Do something with packet.
    }
});

Listen for messages from the remote client as follows:

EngineIoSocket socket;  // socket received in "connection" event

socket.on("message", new Emitter.Listener() {
    @Override
    public void call(Object... args) {
        Object message = args[0];
        // message can be either String or byte[]
        // Do something with message.
    }
});

Send a packet to client as follows:

EngineIoSocket socket;  // socket received in "connection" event

socket.send(new Packet<>(Packet.MESSAGE, "foo"));

WebSockets

Please see the complete documentation on handling WebSockets here.

Features

This library supports all of the features the JS server does, including events, options and upgrading transport.

License

Apache 2.0