Cettia Java Server A is a simple B and scalable C Java server designed to run on any platform on the Java Virtual Machine D.

Cettia 1.0.0-Alpha2 server.
All the interfaces you need to know are Server and ServerSocket. Indeed.
Because servers don't share any data, you can scale application horizontally with ease.
Your application can run on any platform that Asity supports seamlessly i.e. Atmosphere, Grizzly, Java WebSocket API, Netty, Play, Servlet and Vert.x.

Quick Start

Cettia Java Server is distributed through Maven Central and a single artifact, io.cettia:cettia-server:1.0.0-Alpha3, is enough for general purpose. To run an application on the specific platform, you need to prepare the corresponding bridge artifact from Asity. Here to make the application run on an implementation of Servlet 3 and Java WebSocket API 1 io.cettia.asity:asity-bridge-servlet3:1.0.0-Beta1 and io.cettia.asity:asity-bridge-jwa1:1.0.0-Beta1 are used.


Once you’ve set up the build, you will be able to write the following echo and chat server.

import io.cettia.DefaultServer;
import io.cettia.Server;
import io.cettia.ServerSocket;
import io.cettia.asity.action.Action;
import io.cettia.asity.bridge.jwa1.AsityServerEndpoint;
import io.cettia.asity.bridge.servlet3.AsityServlet;
import io.cettia.transport.http.HttpTransportServer;
import io.cettia.transport.websocket.WebSocketTransportServer;

import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRegistration;
import javax.servlet.annotation.WebListener;
import javax.websocket.DeploymentException;
import javax.websocket.server.ServerContainer;
import javax.websocket.server.ServerEndpointConfig;

public class Bootstrap implements ServletContextListener {
  public void contextInitialized(ServletContextEvent event) {
    // A cettia server
    Server server = new DefaultServer();
    // When a socket is created as the beginning of the lifecycle
    server.onsocket((ServerSocket socket) -> {
      System.out.println("on server's socket");
      // Lifecycle events
      // When the handshake is performed successfully
      socket.onopen((Void v) -> System.out.println("on open"));
      // When the underlying transport is closed for some reason
      socket.onclose((Void v) -> System.out.println("on close"));
      // When an error happens on the socket
      socket.onerror((Throwable error) -> error.printStackTrace());
      // When the socket has been closed for a long time i.e. 1 minute and deleted from the server as the end of the lifecycle
      socket.ondelete((Void v) -> System.out.println("on delete"));
       // echo and chat events
      socket.on("echo", (Object data) -> {
        System.out.println("on echo " + data);
        socket.send("echo", data);
      socket.on("chat", (Object data) -> {
        System.out.println("on chat " + data);
        server.all().send("chat", data);

    // Sets up the cettia server on Servlet and Java WebSocket API
    // Of course, you can use other platform without touching the cettia server
    HttpTransportServer httpTransportServer = new HttpTransportServer().ontransport(server);
    ServletContext context = event.getServletContext();
    Servlet servlet = new AsityServlet().onhttp(httpTransportServer);
    ServletRegistration.Dynamic reg = context.addServlet(AsityServlet.class.getName(), servlet);

    final WebSocketTransportServer wsTransportServer = new WebSocketTransportServer().ontransport(server);
    ServerContainer container = (ServerContainer) context.getAttribute(ServerContainer.class.getName());
    ServerEndpointConfig config = ServerEndpointConfig.Builder.create(AsityServerEndpoint.class, "/cettia")
    .configurator(new ServerEndpointConfig.Configurator() {
      public <T> T getEndpointInstance(Class<T> endpointClass) throws InstantiationException {
        return endpointClass.cast(new AsityServerEndpoint().onwebsocket(wsTransportServer));
    try {
    } catch (DeploymentException e) {
      throw new RuntimeException(e);

  public void contextDestroyed(ServletContextEvent sce) {}

Further Reading

  • To play something right now, start with archetype example on your favorite platform.
  • To take a brief look at API, check out the testee.
  • To get details of API, see API document.
  • To have a thorough knowledge of the implementation, read out the reference.