WEB SOCKETSCURRENT STATE

FOR JAVA DEVELOPERS

CURRENT STATE FOR JAVA DEVELOPERS

Web SOCKETS

VIKTORGAMOV

PRESENTEDBY

WEB SOCKETS

BIT OFHISTORY

MEETTHE WEBSOCKETS

WEBSOCKETSIN ACTION

Q & ASESSION

AGENDA

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“LEGACY” WEBPOLLING LONG-POLLING STEAMING

OPTIONS FOR “REALTIME” WEB

Browser sends a request to the server and the server keeps the request open for a set period of time. If a notification is received within that period, a response containing the message is sent to the client. If a notification is not received within the set time period, the server sends a response to terminate the open request.

Browser sends a complete request, but the server sends and maintains an open response that is continuously updated and kept open indefinitely (or for a set period of time)

Browser sends HTTP requests at regular intervals and immediately receives a response. However, real- time data is often not that predictable, making unnecessary requests inevitable and as a result, many connections are opened and closed needlessly in low-message-rate situations

WHAT IS WEBSOCKET

“Reducing kilobytes of data to 2 bytes... and reducing latency from 150ms to 50 ms is far more than marginal. In fact, these two factors alone are enough to make WebSocket seriously interesting...”

www.ietf.org/mail-archive/web/hybi/current/msg00784.html

WEB SOCKETSTANDARD PROTOCOL CLIENT-SIDE API SERVER-SIDE API

WHAT IS WEBSOCKETS?

HTML5 specification introduces WebSocket client side object. No plugin required.

True real-time server updates. Expected large penetration in Java world with upcoming JavaEE 7 spec and JSR-356

Websocket is a standardized technology (described in RFC6455) to support low-overhead bidirectional traffic from your Web browser.

1 2 3 4

SEND

UPGRADEREQUEST

RECEIVE

UPGRADERESPONSE

CHANGE

READYSTATETO OPEN

LISTEN

MESSAGEEVENT

WEBSOCKET HANDSHAKE

To Start full-duplex communication client should send UPGRADE request

DEMO

HANDSHAKE DEMO

WEBSOCKET INTERFACE

[Constructor(DOMString  url,  optional  (DOMString  or  DOMString[])  protocols)]interface  WebSocket  :  EventTarget  {    readonly  attribute  DOMString  url;

   //  ready  state    const  unsigned  short  CONNECTING  =  0;    const  unsigned  short  OPEN  =  1;    const  unsigned  short  CLOSING  =  2;    const  unsigned  short  CLOSED  =  3;    readonly  attribute  unsigned  short  readyState;    readonly  attribute  unsigned  long  bufferedAmount;

   //  networking    [TreatNonCallableAsNull]  attribute  Function?  onopen;    [TreatNonCallableAsNull]  attribute  Function?  onerror;    [TreatNonCallableAsNull]  attribute  Function?  onclose;    readonly  attribute  DOMString  extensions;    readonly  attribute  DOMString  protocol;    void  close([Clamp]  optional  unsigned  short  code,  optional  DOMString  reason);

   //  messaging    [TreatNonCallableAsNull]  attribute  Function?  onmessage;                      attribute  DOMString  binaryType;    void  send(DOMString  data);    void  send(ArrayBufferView  data);    void  send(Blob  data);};

CLIENT-SIDE WEBSOCKET API

var  ws;if  (window.WebSocket)  {        output("WebSocket  supported  in  your  browser");        ws  =  new  WebSocket("ws://www.websockets.org");

       //  Set  event  handlers.        ws.onopen  =  function  ()  {                output("onopen");        };        ws.onmessage  =  function  (e)  {                //  e.data  contains  received  string.                output("echo  from  server  :  "  +  e.data);        };        ws.onclose  =  function  ()  {                output("onclose");        };        ws.onerror  =  function  ()  {                output("onerror");        };

}else  {output("WebSocket  not  supported  in  your  browser");}

JAVA EE 7 SERVER-SIDE API

package  org.javaee.glassfishwebsocket;

import  org.glassfish.websocket.api.annotations.WebSocket;import  org.glassfish.websocket.api.annotations.WebSocketMessage;

@WebSocket(path  =  "/echo")public  class  EchoBean  {        @WebSocketMessage        public  String  echo(String  message)  {                System.out.println("#####################  Message  received");                return  message  +  "  (from  your  server)";        }}

TOMCAT 7.0.29 SERVER-SIDE API

SHOW THE

CODENot enough room for code in this slide ;-)

PROGRAMMING WEBSOCKETS

Client-side frameworks

✦jquery.socket.js✦https://github.com/flowersinthesand/jquery-socket/wiki

✦atmosphere.js✦https://github.com/Atmosphere/atmosphere/wiki/jQuery.atmosphere.js-API

✦socket.io

WEBSOCKET SUPPORT

JAVA-based Web servers with native support.The WebServer has API for WebSocket

✦Netty 3.3.x✦Jetty 7.x, 8.x✦Glassfish 3.1.2✦Tomcat 7.0.27

WHAT SHOULD WE DO?

WE CAN DO IT!

WHAT IS ATMOSPHERE

Atmosphere https://github.com/Atmosphere/atmosphere/

✦portable framework for✦long-polling✦Streaming✦Server-Send Events✦WebSockets

✦can auto select best transport✦abstracting from actual underlying container mechanism

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THINKING ABOUT USE CASES

OUR CLIENTSUSE CASE

WebSockets really shine with following applications:

✦Live trading/sports ticker✦Controlling medical equipment over the web✦Chat applications✦Multiplayer online games✦Realtime updating social streams

BUNCH OF USEFUL LINKS

✦http://www.w3.org/TR/websockets/ MUST!✦http://tools.ietf.org/html/rfc6455 MUST!✦http://tomcat.apache.org/tomcat-7.0-doc/web-socket-howto.html✦http://websocket-sdk.java.net/Introduction.html✦https://github.com/Atmosphere/atmosphere/wiki/Supported-WebServers-and-Browsers✦http://autobahn.ws/testsuite

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