Jetty 9 & Websockets Example

Jetty is best webserver for Embedded application  deployment.  I don’t want to change the slogan of Jetty to make it understand in a better way  , it was defined in a simple way like below .

"Jetty has a slogan, "Don't deploy your application in Jetty, deploy Jetty in your application." What this means is that as an alternative to bundling your application as a standard WAR to be deployed in Jetty, Jetty is designed to be a software component that can be instantiated and used in a Java program just like any POJO. Put another way, running Jetty in embedded mode means putting an HTTP module into your application, rather than putting your application into an HTTP server.  "

Simple Idea about Jetty:

Jetty  is nothing but adding the Http Server  component in your application. I would like to take this opportunity  to share my experience  with customized http server application .  I used Apache HTTP COMPONENTS for HTTP server application, which is a good option for simple http interactions.

Better  Deployment:

Jetty has introduced the "jetty.base" in Jetty 9 onwards  to isolate  the configuration with other  content like  lib,xml files,start script. SO in Jetty Base we can expect the logs,webapps,start.ini(configuration file) and start.d.

Start of Jetty :

As we know that we have executable jar file in java , in the same way we have executable jar file for starting the Jetty Server.

> java -jar start.jar

You can also add arguments to above statement for server startup command to change  the behavior of Jetty.

If you need any better options please use  "--help" at the end of above start command.  You will get know Module Management,Start,ShutDown,Classpath,Loglevels, log location etc…

" java -jar start.jar --help".

First thing we want to change PORT of Jetty :

Unix Version:

jetty.home = Jetty base directory (jetty-distribution-9.1.4.v20140401).

Windows Version:

JETTY_HOME = Jetty base directory (jetty-distribution-9.1.4.v20140401).

Path : $jetty.home/Start.d/http.ini

# HTTP port to listen on

jetty.port=8080

You can also change port from command start using jetty.port command like below:

c:\> java  -jar start.jar -jetty.port=9999

After executing above command  jetty will start on port 9999.

WebSockets in Jetty :

Jetty has different implementation on different versions. If you are using version lesser than Jetty 9.x then implementation will  be bit tough. From Jetty 9.x onwards they have solid and flexible implementation. Thanks to Jetty Team of Contributors. Here I am using Jetty Latest Version of today (jetty-distribution-9.1.4.v20140401). This implementation strictly doesn't support backward compatibility.

I am explaining about the Websocket usage with Jetty API.

We have 3 ways to do the things :

1. Listener Design
2. Annotation
3. Adapter

A WebSocket TEXT Message can only ever be UTF-8 encoded. (if  you need other forms of encoding, use a BINARY Message).

A WebSocket BINARY Message can be anything that will fit in a byte array.

Jetty Implemented  Websocks:

Step-1 :

We have to create the WebSocketServlet .

package com.webapps.token;

import javax.servlet.annotation.WebServlet;

import org.apache.log4j.Logger;

import org.eclipse.jetty.websocket.servlet.WebSocketServlet;

import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;

@WebServlet(name = "MyEcho WebSocket Servlet", urlPatterns = { "/websocks" })

public class MyWebSockServlet extends WebSocketServlet

{

private static final Logger log = Logger.getLogger(MyWebSockServlet.class);

/**

 *

 */

private static final long serialVersionUID = -7560239504376396230L;

@Override

public void configure(WebSocketServletFactory wsfactory)

{

log.debug(" Configured the WebSockFactory");

 // register a socket class as default

//wsfactory.getPolicy().setIdleTimeout(10000);

        wsfactory.register(TokenWebSocket.class);

}

}

Step-2:

Create the websocket which register in Websocket factory.

package com.webapps.token;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import org.apache.commons.codec.binary.Hex;

import org.apache.log4j.Logger;

import org.eclipse.jetty.websocket.api.RemoteEndpoint;

import org.eclipse.jetty.websocket.api.Session;

import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;

import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;

import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;

import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;

@WebSocket(maxBinaryMessageSize = 4 * 1024 * 1024,maxTextMessageSize= 4 * 1024 * 1024)

public class TokenWebSocket

{

private static final Logger log = Logger.getLogger(TokenWebSocket.class);

private String log_prefix="<mws>:";

@OnWebSocketMessage

public void onWebSocketBinary(Session session,byte[] payload, int offset, int length)

{

// TODO Auto-generated method stub

log.debug("onWebSocketBinary Called");

String test= new String(payload);

log.debug("Binary payload:["+test+"]");

 // simple TEXT message received, with Connection

     // that it occurred on.

log.debug(" on Text Message Called ");

RemoteEndpoint remote = session.getRemote();

log.debug("Message:Rcvd["+test+"]");

try {

//remote.sendString(test+" OK  Bingo!!!");

remote.sendBytes(ByteBuffer.wrap((test+"  OK Bing0!!!!").getBytes()));

} catch (Exception e) {

// TODO Auto-generated catch block

log.error("whie senfing ", e);

}

}

@OnWebSocketClose

public void onWebSocketClose(Session session,int statusCode, String reason)

{

session.close();

log.debug("onWebSocketClose Called .....statuscode ["+statusCode+"] reason ["+reason+"]");

}

@OnWebSocketConnect

public void onWebSocketConnect(Session session)

{

InetSocketAddress remoteAddr = session.getRemoteAddress();

log.debug("<ws-open>: Remote IP ["+remoteAddr.getAddress().getHostAddress()+"] :Port["+remoteAddr.getPort()+"] SessionID:["+session.getProtocolVersion()+"]");

}

@OnWebSocketError

public void onWebSocketError(Session session,Throwable exception) {

this.webSession.close();

exception.printStackTrace(System.err);

}

@OnWebSocketMessage

public void onTextMethod(Session session, String message)

{

     // simple TEXT message received, with Connection

     // that it occurred on.

log.debug(" on Text Message Called ");

RemoteEndpoint remote = session.getRemote();

log.debug("Message:Rcvd["+message+"]");

try {

remote.sendString(message+" OK  Bingo!!!");

} catch (Exception e) {

// TODO Auto-generated catch block

log.error("whie sending ", e);

}

// Async Send of a BINARY message to remote endpoint

/*ByteBuffer buf = ByteBuffer.wrap(new byte[] { 0x11, 0x22, 0x33, 0x44 });

Future<Void> fut = null;

try

{

    fut = remote.sendBytesByFuture(buf);

    // wait for completion (timeout)

    fut.get(2,TimeUnit.SECONDS);

}

catch ( InterruptedException e)

{

    e.printStackTrace();

}

catch (TimeoutException e)

{

    e.printStackTrace();

    if (fut != null)

    {

        fut.cancel(true);

    }

} catch (ExecutionException e) {

e.printStackTrace();

}finally{

log.debug(" ON Message Text Done !!!!!!");

}*/

}

}

Step- 3:

Add these to your source package and deploy in Jetty server, that’s it . This is the tested code.

I will upload the total zip of source soon.