WEB SOCKETS CURRENT STATE FOR JAVA DEVELOPERS 

CURRENT STATE FOR JAVA DEVELOPERS Web SOCKETS VIKTOR GAMOV PRESENTED BY 

WEB SOCKETS BIT OF HISTORY MEET THE WEBSOCKETS WEBSOCKETS IN ACTION Q & A SESSION AGENDA ? 

“LEGACY” WEB POLLING 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 SOCKET STANDARD 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 UPGRADE REQUEST RECEIVE UPGRADE RESPONSE CHANGE READYSTATE TO OPEN LISTEN MESSAGE EVENT WEBSOCKET HANDSHAKE To Start full-duplex communication client should send UPGRADE request 

DEMO HANDSHAKE DEMO 

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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 CODE Not 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 

? THINKING ABOUT USE CASES 

OUR CLIENTS USE 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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