Building Java Html5

8/10/2019 Building Java Html5

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Java API for WebSocketsOTN Developer Days - India

David Delabassee - @delabasseeSoftware Evangelist - Oracle


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2 Copyright 2013, Oracle and/or its affiliates. All rights reserved.

Java EE 7 The Latest in Enterprise Java


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Agenda

Introduction to WebSockets

What are they for ?

Delving into the APIs


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Interactive Web Sites

Flavors of Server Push

Polling

Long polling

Comet/AJAX

Complex, inefficient, wasteful


5/645Copyright 2013, Oracle and/or its affiliates. All rights reserved.

WebSockets to the rescue

TCP based, bi-directional, full-duplex messaging

IETF defined protocol: RFC 6455

Part of HTML5

W3C defined JavaScript API


6/646 Copyright 2013, Oracle and/or its affiliates. All rights reserved.

But can I use WebSockets?

http://caniuse.com/websockets


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Click to edit Master text styles

Browsers and WebSockets

http://caniuse.com/websockets


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Whats the basic idea ?

Establish a WebSocket connection

Send messages backwards and forwards

End the connection


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Establish a connection

Ap

Browser,

Rich Client,Application Server,

!

Handshake Response

Handshake Request


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Connected !


Establishing a connection

Handshake Response

Handshake Request


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Http Request

GET /mychat HTTP/1.1

Host: server.example.com

Upgrade: websocket

Connection: Upgrade

Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==Sec-WebSocket-Protocol: megachat, chat

Sec-WebSocket-Extensions : compress, mux

Sec-WebSocket-Version: 13

Origin: http://example.com

Handshake Request


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Handshake Response

Http Response

HTTP/1.1 101 Switching Protocols

Upgrade: websocket

Connection: Upgrade

Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaG

Sec-WebSocket-Protocol: chatSec-WebSocket-Extensions: compress, mux


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Fundamentals


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Endpoints

Browser

JavaEndpoint

JavaJavaFX

JavaEndpoint

JavaScriptEndpoint


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Connected !


Lifecycle

open open

message

message

message

error

close

Disconnected !

close


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WebSockets Endpoints

Create Java classes that are WebSocket endpoints

The endpoint implements all the WebSocket functionalit

Endpoints can be

Annotated - POJO + Annotations

Programmatic - Java classes that extend WebSocket API


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Hello World Server

@ServerEndpoint("/echo")public class EchoServer {

@OnMessage

public String echo(String incomingMessage) {

return Hello " + incomingMessage;

}

}


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Hello World Server

public class EchoServerextends Endpoint{

@Override

public void onOpen(Session session, EndpointConfig endpointCon

final Session mySession = session;

mySession.addMessageHandler(newMessageHandler.Whole()

@Override

public void onMessage(String text) {

try {mySession.getBasicRemote().sendText("I got " + text

} catch (IOException ioe) {

System.out.println(Oops " + ioe.getMessage());

}}});

}

}


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Hello World Client

@ClientEndpoint

public class HelloClient {

@OnOpen

public void init(Session session) {

try {

session.getBasicRemote().sendText("Hello you!");

} catch (IOException ioe) {

// oops

}

}

}


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Hello World Client

public class MyClient extends Endpoint{

@Override

public void onOpen(final Session session, EndpointConfi

session.addMessageHandler(new MessageHandler.Whole

@Override

public void onMessage(String text) {

System.out.println("Received: " + text);

}

});

try {

session.getBasicRemote().sendText(Duke);} catch (IOException ex) {

// Ooops

}

}

}


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Hello World Client

public class MyClient extends Endpoint{

@Overridepublic void onOpen(final Session session, EndpointConfi

try {

session.getBasicRemote().sendText(Hello again!

} catch (IOException ex) {

// Ooops

}

}


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Hello Client - Bootstrap

WebSocketContainer container =

ContainerProvider.getWebSocketCont

String uri = "ws://myServer:8080/websocket";

container.connectToServer(MyClient.class, null, URI.creat


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Intercepting WebSocket events

Annotated

Endpoints

Programmatic Endpointjavax.websocket.Endpointmetho

Open event @OnOpenpublic void onOpen(Session ses

EndpointCon

Message event @OnMessageCreate and register an instance of a

javax.websocket.MessageHa

Error event @OnErrorpublic void onError(Session se

Throwable

Close event @OnClosepublic void onClose(Session se

CloseReaso


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Messaging

M


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Message

Payload

Text

Binary

Ping-Pong

Sync / Asynch

Whole message / Sequence of partial messages

No delivery guarantee!

S di


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Use theRemoteEndpointinterface, obtained from the SessiomySession.getBasicRemote().sendText(Hello);

Return a value from your @OnMessagemethod (convenience)

@OnMessage

public String echo(String incomingMessage) {

return(Hello);

}

Sending messages

S di


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Click to edit Master text stylesMeans of sending RemoteEndpoint method to

as whole string sendText(String message)

as binary data sendBinary(ByteBuffer message)

in string fragments sendText(String part, boolean las

in binary data fragments sendBinary(ByteBuffer part, boole

as a blocking stream of text Writer getSendWriter())

as a blocking stream of binary data OutputStream getSendStream()

as a custom object of type T sendObject(T customObject)

Sending messages

R i i


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Receiving messages

Annotation - Annotated a suitable method with@OnMessage

@OnMessage

public void gettingAText(String message)

@OnMessage

public void gettingPartialText(String message, boolean i

Programmatic - Implement aMessageHandler, add it to theSe

MyTextMessageHandler implements MessageHandler.Whole


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Receive a message - @OnMessage

Text

public void handleText(String message)

public void handleReader(Reader r)public void handleTextPieces(String message, boole

Binarypublic void handleBinary(ByteBuffer bb)

public void handleStream(InputStream is)

public void handleBinaryPieces(ByteBuffer bb, bool

Any object public void handleObject(CustomObject co)

Recei e a message Programmaticall


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Receive a message - Programmatically

Text

MessageHandler.Whole

MessageHandler.PartialMessageHandler.Whole

BinaryMessageHandler.Whole

MessageHandler.Partial

MessageHandler.Whole

Any object MessageHandler.Whole

session.addMessageHandler();

Sending Java Object


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Sending Java Object

Java primitive

Text

x.toString()

Java Object

Custom javax.websocket.Encoderimplementation

Text or binary

Encoders and Decoders


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Encoder

Object to Binary: Encoder.Binary,Encoder.Bina

Object to Text: Encoder.Text,Encoder.TextStre

Decoder

Text to Object: Decoder.Text,Decoder.TextStre

Binary to Object: Decoder.Binary,Decoder.Bina

Lifecycle

init()and destroy() methods

willDecode ()

Encoders and Decoders

Custom Payload Text


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Custom Payload - Text

public class MyMessage implements Decoder.Text,Encoder.Text {

privateJsonObjectjsonObject;

public booleanwillDecode(String string) {

return true; // Only if can process the payload }

public MyMessagedecode(String s) {

jsonObject = new JsonReader(new StringReader(s)).readObje

return this;

}

public Stringencode(MyMessage myMessage) {

return myMessage.jsonObject.toString();

}

}

Custom Payload Binary


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Custom Payload - Binary

public class MyMessage implements Decoder.Binary,Encoder.Binary {

public booleanwillDecode(byte[]bytes) {...

return true; // Only if can process the payload

}

public MyMessage decode(byte[] bytes) {

...

return this;

}

public byte[] encode(MyMessage myMessage) {

...}

}

Encoders and Decoders Configurations


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Encoders and Decoders - Configurations

@ServerEndpoint(

decoders = { Foo.class, Bar.class },

encoders = { Baz.class, Forz.class })

List myEncoders = new List();

myEncoders.add(Foo.class);

myEncoders.add(Bar.class);ServerEndpointConfig myConfig =

ServerEndpointConfig.Builder.create(MyEp.class, "/

.encoders(myEncoders)

.build();


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Configuration and Sessions

Instance diagram of EndpointConfigs and Se


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Instance diagram of EndpointConfigs and Se

LogicalEndpoint

Client A

EndpoiSessionA

Client B

SessionB Endpoi

Serv

User state and endpoint state


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User state and endpoint state

Session

Representation of the WebSocket connection with a peer

One instance per peer

Has property bag for per peer endpoint application state

ServerEndpointConfig

Holds all the configuration information for a logical endpoint

One instance per logical endpoint

Has property bag for per logical endpoint application state

Can extend EndpointConfigto add behavior

Storing Chat application state


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Storing Chat application state

LogicalEndpoint

John

Endpoint JSession J

Sally

Session S Endpoint S

Sally

John Serv


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Advanced Messaging

Synchronous and Asynchronous sending


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Synchronous and Asynchronous sending

Ping and pong

RemoteEndpoint.sendPing(ByteBuffer bb)

RemoteEndpoint.sendPong(ByteBuffer bb)

Synchronous send

Most commonly used mode

RemoteEndpoint.Basic, send methods block until transmcomplete

Asynchronous send modesUse the RemoteEndpoint.Asyncinterface, send methods

immediately, before transmission completes

send by Future: send methods return a Futureobject

send by completion: send methods take a callback listener

To batch or not to batch messages


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client

Copyright 2013, Oracle and/or its affiliates. All rights reserved.

To batch or not to batch messages

Server

client

endpoint

batch

m

m

m

mm m

mm

m batch

Batching


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Batching

Not supported by all implementationsGood for high frequency messaging applications

Application has to permit it for the implementation to use it

RemoteEndpoint.getBatchingAllowed()

RemoteEndpoint.setBatchingAllowed(boolean al

If you use batching, you may need to flush the buffers

RemoteEndpoint.flushBatch()


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WebSocket Path Mapping

WebSocket Path Anatomy


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y

Web Container

Client

WAR

Endpoint

URL Endpoint

endpoint path:

WAR context root: mywebServer hostname: www.myapps.c

ws://www.myapps.com/mywebapp/f

Path Types - exact URI


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yp

Server endpoints can be mapped to exact URI

Example /fooor/airlines/seating/updater

/foo !=/Foo

Implementations use an exact match policy

Cant have 2 endpoints mapped to the same URI in the sam

Path Types - URI Template


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yp p

URI-Template

Level 1, i.e. simple string extension

Example /travel/{mode}

/travel/{mode}/{class}

Match if incoming URI is a valid expansion of the URI temp

/travel/boat , /travel/plane !

/travel , /travel/steam/train "

Cant have two equivalent URI-templates in an application

/travel/{mode} + /travel/{vip}

"

Expanded parameters can be retrieved by name inside the

URI Template and Path Parameter


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p

@ServerEnpoint("/travel/{mode}")

public class Trip {

@OnOpen

public void Booking ( @PathParam("mode") String travel

switch (travelMode) {

case#

"plane"#

:. . .

URI Template and Path Parameter


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p

@ServerEnpoint("/travel/{mode}/{class}")

public class Trip {

@OnOpen

public void Booking (Session session, EndpointConfig c

Map pathParam = session.getPathPara

String travelMode = pathParam.get("mode");String travelClass = pathParam.get("class");

. . .

}

URI Template, Path Parameter and Query


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y

ws://masterTrip.com/travel/plane?destination=rome

@OnOpen

public void makeOffer(Session session, EndpointConfig

String targetLocation =

session.getRequestParameterMap().get("destinat

. . .


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Based on the Servlet model

WebSocket Endpoints are considered resources via their ur

Require users be authenticated to access a WebSocket end

Limit access to a WebSocket endpoint

to certain users, via role mapping

to an encrypted protocol (wss://)API to give at runtime a view on the security model

Endpoint Configuration


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Control the instantiation and initialization of EndpointAccess the initial HTTP request

Eg. Perform custom checks

Modify the handshake response

Choose a subprotocol from those requested by the client

ServerEndpointConfig.Builder

.create(MyEndpoint.class, /myUri


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Wrap up

WebSocket


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Concepts

Session, Endpoints, Lifecycle

Java API for WebSocket

Annotation & Programmatic based

Part of Java EE 7

Annotations


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Annotation Level Purpose

@ServerEndpoint

class Turns a POJO into a WebSocket En

@ClientEndpoint

class Turns a POJO into a WebSocket Cli

@OnMessage

method Intercepts WebSocket Message eve

@OnOpen

method Intercepts WebSocket Open events

@OnError

method Intercepts errors during a conversat

@OnClose

method Intercepts WebSocket Close events

@PathParam

methodparam

Flags a matched path segment of a

WebSocket


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Advanced

Security

Synch/Asynchronous

Protocols

Batching

Endpoint Config!

Considerations

Firewall

Tools


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customer_access

Account Info

/account.jsp

/account/info

/banner/secure

customer

premium_customer

CONFIDENTIAL


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...

login access

Account Info

/index.jsp

CONFIDENTIAL

BASICfile

customer

premium_customer

...

Make sure

is only avai

Use (encry

auth.

User

use th

Resources


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Java EE 7 Tutorial

Java WebSocket Programming (Oracle Press)

https://blogs.oracle.com/theaquarium/

Get started now!


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NetBeans bundles GlassFish

Incremental compilation; auto-deployComplete Java EE 7 support

All Java EE 7 project types

HTML5 features available in Java EE projects

Maven Support

Advanced Wizards

Entity to REST generation, DB to JSF 2.2 ...

Embedded WebKit browser

Network Monitor


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The preceding is intended to outline our general product directiointended for information purposes only, and may not be incorp

into any contract. It is not a commitment to deliver any materialor functionality, and should not be relied upon in making purc

decisions. The development, release, and timing of any featufunctionality described for Oracles products remains at th

discretion of Oracle.


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