jwebsocket mobiletechcon 2010 - websockets on android, symbian and blackberry

Stay ConnectedMobile Pushing Apps with WebSockets

Alexander SchulzePredrag Stojadinovic

jWebSocket – Open Source Cross-Browser/Cross-Platform WebSocket Solution

Today's session

• Agenda• Communication with WebSockets

Where, What, Why, How• WebSocket Server and Browser Client• WebSocket Communication for mobile Apps• Android Demos and Code Examples

jWebSocket – Stay Connected 205/03/23

Apps in Transition

• More communication rather than pure information• Entertainment, immediate experience exchange

• We will be online more and more• Text, Photos, Videos, Music, Geo-Location, etc.

• Solutions for stationary and mobile devices• Merge Browser, Desktop and Mobile Apps

• WebSockets help to better connect the users


WebSockets Basics

• WebSockets are bidirectional and permanent• Efficient real-time communication rather than

the cumbersome Request/Response Protocol

• WebSockets help achieve interoperability• Standardized handshaking and packet exchange

for stationary and mobile platforms

• Web and Mobile Apps need...• safe, reliable and fast communication


What we have: HTTP

• HTTP - designed for the transmission of documents

• All cumbersome, nearly real-time tricks...• Polling, Reverse-AJAX• Chunking, Comet etc...

• ... are ultimately not standardized hacks!

• HTTP remains a Request/Response mechanism


Nearly Realtime Mechanisms

• Polling• Sending regular requests with immediate response• Many connections, high volume, low efficiency

(especially at low data rate)

• Long Polling• Regular requests with keeping the connection open• High volume, two canals per client, buffering problem,

many connections (especially at high data rate)


Costs

• HTTP volume and bandwidth calculation• Taking: 800 Bytes for Request+Response (up to 2KB)• 1.000 Clients x 800 Bytes = 800 KB => 6,4 Mbit/s• 10.000 Clients x 800 Bytes = 8 MB => 64 Mbit/s• 100.000 Clients x 800 Bytes = 80 MB => 640 Mbit/s

• And that's only for the protocol - no user data!


WebSockets ?

• WebSockets – What is it ?• Bi-directional full-duplex protocol between

the Browser client and the WebSocket server• Equally usable for desktop and mobile apps• Designed for permanent / long-lasting connections• Standardized in HTML 5, W3C API, IETF-Protocol

(http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76)

• WebSockets are TCP - not HTTP - based!


TCP instead of HTTP

• Freedom of extendability• No binding to specific data formats• No rules for content or processing

• But also high responsibility• Data formats and communication logic

must be implemented• As well as all security mechanisms!


Establishing Connection

• Handshake


ClientGET {path} HTTP/1.1Upgrade: WebSocketConnection: UpgradeHost: {hostname}:{port}Origin: http://{host}[:{port}]Sec-WebSocket-Key1: {sec-key1}Sec-WebSocket-Key2: {sec-key2}

8 Bytes generated {sec-key3}

Establishing Connection

• Handshake (Same Origin Policy, IETF Draft #76)


ClientGET /services/chat/;room=Foyer HTTP/1.1Upgrade: WebSocketConnection: UpgradeHost: jwebsocket.orgOrigin: http://jwebsocket.orgSec-WebSocket-Key1: 4 @1 46546xW%0l 1 5Sec-WebSocket-Key2: 12998 5 Y3 1 .P00

^n:ds[4U

ServerHTTP/1.1 101 WebSocket Protocol HandshakeUpgrade: WebSocketConnection: UpgradeSec-WebSocket-Origin: http://jwebsocket.orgSec-WebSocket-Location: ws://jwebsocket.org/ services/chat

8jKS'y:G*Co,Wxa-

Bi-directional data exchange

• Text frames (released)• 0x00 <UTF-8 text data> 0xFF• Theoretically no length limit, JavaScript: 4 GB

• Binary frames (not yet released)• 0x80-0xFF <length> <binary data>

• The WebSocket Protocol is alive!• Current IETF Draft # 76 (Changes expected)


WebSockets TCP vs. HTTP

• WebSockets volume and bandwidth calculation• Fixed: 2 Bytes for Request+Response• 1.000 Clients x 2 Bytes = 2 KB => 0,016 Mbit/s• 10.000 Clients x 2 Bytes = 20 KB => 0,16 Mbit/s• 100.000 Clients x 2 Bytes = 200 KB => 1,6 Mbit/s

• Protocol overhead: four hundred times smaller!


WebSockets – Why?

• Faster, cheaper, more open• Leaner communication (TCP vs. HTTP overhead)

WebSockets gradually replacing XHR and Comet• Uses only one channel (bidirectional, full-duplex)

• Resource and cost reducing,twice as many clients simultaneously per server

• No protocol specifications or binding to specific data formats


WebSockets – What for

• WebSockets are perfect for ...• Online-Games and Online-Collaboration• Remote Control and Monitoring• Streaming and Chat• Social Networks• Clusters and Grids


HTML5 Browser

• WebSockets in the Browser


var lWebSocketClient = new WebSocket("ws://jwebsocket.org:8787"); // tries to open the TCP connection and to exchange handshake

lWebSocketClient.onopen = function(aEvent) { // connection has successfully been established}lWebSocketClient.onmessage = function(aEvent) { // a data packet has completely been received in aEvent.data}lWebSocketClient.onclose = function(aEvent) { // the connection has been terminated}lWebSocketClient.send("Hello World!"); // sends a UTF-8 text message to the server

lWebSocketClient.close(); // terminates the connection

Compatibility

• X-Browser and X-Plattform compatible• Nativ in Chrome 4/5/6, Firefox 4, Safari 5,

IE 6/7/8, Opera 9/10 and older Browserswith FlashBridge

• Clients for Android, Symbian and BlackBerry,iPhone from December 2010


Token

• jWebSocket Token Model• All nodes in a WebSocket network are stupid at first• All parties must agree on a common language to

“understand” incoming packets• For example, JSON, XML, or CSV• Abstract: Data objects,

in form of a jWebSocket “Token”


jWebSocket Server

• Server Infrastructure• Engines• Tokens• Server• Filter• Plug-Ins• Listener


jWebSocket JavaScript Client

• Client Infrastructure• Basic WebSocket Client• Token Client• Extendable with Plug-Ins

• Features• Connection Management• Session Management• Authentication and authorization


WebSockets – How?

• Libraries already available (open source, LGPL)• Browser Client in JavaScript

jWebSocket.js including FlashBridge and JSON Support• jWebSocket Server

as .jar, .war, .exe or as a service• Client for Java SE e.g. for Swing Desktop Apps• Clients for Android, Symbian and BlackBerry

(iPhone from Dezember 2010)


Android - Dalvik VM

• Android Apps in Java• In principle, Java 1.5, incl. collections, annotations, etc.• Google's own Dalvik VM: optimized for Mobile Devices,

very compact, but not byte-code compatible• As already discovered in Java ME:

“Write Once Run everwhere” belongs to the past• Special Android builds of the libraries are necessary,

re- compile your own and third-party libs from source


Low-Level-Interface

• Java Client for Android, Symbian and BlackBerry


public interface WebSocketClient { void open(String aURL) throws WebSocketException; void send(WebSocketPacket aPacket) throws WebSocketException; void close() throws WebSocketException; boolean isConnected();

void addListener(WebSocketClientListener aListener); void removeListener(WebSocketClientListener aListener);

void notifyOpened(WebSocketClientEvent aEvent); void notifyPacket(WebSocketClientEvent aEvent, WebSocketPacket(aPacket); void notifyClosed(WebSocketClientEvent aEvent);}

Listener

• The same API as in the Web Clients


public interface WebSocketClientListener {

void processOpened(WebSocketClientEvent aEvent);

void processPaket(WebSocketClientEvent aEvent, WebSocketPacket aPacket);

void processClosed(WebSocketClientEvent aEvent);

}

Java WebSocket Client


Android Demo App

• MainActivity• ListView

• ConfigActivity• URL• Username• Password


Android Fundamentals


• WebSocket App• Establish connection• Receive messages• Send messages• Broadcast messages• Disconnect

Android Canvas Demo

• Online-Collaboration• Multiple users work on the

same document• Example:

SharedCanvas


Android - transfer photos

• Image Transfer• jWebSocket FileSystem Plug-In• Notification of changes• Binary data Base64 encoded,

optimization with a new binaryprotocol expected soon

• http://jwebsocket.org/Snapshot Demo!


Overview

• We have big plans...• SSO and Authentication/Authorization API• Remote Procedure Calls (RPC)• Cloud API, Smart Grids and Clusters• Shared Objects and FileSharing API• JDBC Bridge and Database API• External Service Nodes


In-house

• The jWebSocket team is looking for support!• Java EE, SE, ME, JavaScript, Objective C...• Android, Symbian, BlackBerry, iPhone...• Ideas for innovative apps welcome!

• We offer...• Extensive experience of an international team• First Class support for your own projects• Support in building your own reputation


Thank you for your attention!

Questions & AnswersAlexander Schulze

Predrag Stojadinovic

Forum & Downloadhttp://jwebsocket.org @jWebSocket


jwebsocket mobiletechcon 2010 - websockets on android, symbian and blackberry

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