Building Java HTML5/WebSocket Applications with JSR 356

Transcription

1 Building Java HTML5/WebSocket Applications with JSR 356

2 Program Agenda WebSocket Primer JSR 356: Java API for WebSocket Demo 2

3 Interactive Web Sites HTTP is half-duplex Flavors of Server Push Polling Long Polling Comet/Ajax Complex, Inefficient, Wasteful 3

4 WebSocket to the Rescue TCP based, bi-directional, full-duplex messaging Originally proposed as part of HTML5 IETF-defined Protocol: RFC 6455 W3C defined JavaScript API 4

5 What s the basic idea? Establish connection (Single TCP connection) Send messages in both direction (Bi-directional) Send message independent of each other (Full Duplex) End connection 5

6 Establish a connection Handshake Request Client Handshake Response Server 6

7 Handshake Request GET /chat HTTP/1.1 Host: server.example.com Upgrade: websocket Connection: Upgrade Sec-WebSocket-Key: dghlihnhbxbszsbub25jzq== Origin: Sec-WebSocket-Protocol: chat, superchat Sec-WebSocket-Version: 13 7

8 Handshake Response HTTP/ Switching Protocols Upgrade: websocket Connection: Upgrade Sec-WebSocket-Accept: s3pplmbitxaq9kygzzhzrbk+xoo= Sec-WebSocket-Protocol: chat 8

9 Establishing a Connection Handshake Request Client Handshake Response Server Connected! 9

10 WebSocket Lifecycle Connected! open open Client message error message message message Server close Disconnected 10

11 WebSocket API 11

12 Java WebSocket Implementations Java-WebSocket Grizzly Apache Tomcat 7 GlassFish Autobahn WeberKnecht Jetty JBoss Caucho Resin jwebsocket Kaazing WebSocket Gateway WebSocket SDK Webbit Atmosphere websockets4j GNU WebSocket4J Netty TorqueBox SwaggerSocket jwamp 12

13 Browser Support 13

14 JSR 356: Java API for Web Socket Specification Included in Java EE 7 Reference Implementation Bundled with Glassfish 4 14

15 Java API for WebSocket Features Create WebSocket Endpoints Interface-driven (Endpoint) Annotation-driven Client and server APIs SPI for extensions and data frames 15

16 Basic API Tour 16

17 Hello World Server public class HelloServer extends Endpoint public void onopen(session session, EndpointConfig configuration) { session.addmessagehandler( new MessageHandler.Whole<String>() { public void onmessage(string name) { try { session.getbasicremote().sendtext( Hello + name); catch (IOException ioe) { // Handle failure. ); 17

18 Hello World Client public class HelloClient extends Endpoint public void onopen(session session, EndpointConfig configuration) { try { session.getbasicremote().sendtext("hello you!"); catch (IOException ioe) {... 18

19 Client Server Configuration ServerContainer servercontainer = (ServerContainer) servletcontext.getattribute( javax.websocket.server.servercontainer ); ServerEndpointConfig serverconfiguration = ServerEndpointConfig.Builder.create( HelloServer.class, "/hello").build(); servercontainer.addendpoint(serverconfiguration);... URI clienturi = new URI("ws://myserver.com/websockets/hello"); WebSocketContainer container = ContainerProvider.getWebSocketContainer(); ClientEndpointConfig clientconfiguration = ClientEndpointConfig.Builder.create().build(); container.connecttoserver(helloclient.class, clientconfiguration, clienturi); 19

20 Main API Classes: javax.websocket.* Endpoint: Intercepts WebSocket lifecycle events MessageHandler: Handles all incoming messages for an Endpoint RemoteEndpoint: Represents the other end of this conversation Session: Represents the active conversation 20

21 WebSocket Endpoint Object Model Client Remote Endpoint Session Message Handler Client Remote Endpoint Internet Session Message Handler Client Remote Endpoint Session Message Handler 21

22 Sending the Message Whole string * RemoteEndpoint.Basic sendtext(string message) Binary data * RemoteEndpoint.Basic sendbinary(bytebuffer message) String fragments RemoteEndpoint.Basic sendtext(string part, boolean last) Binary data fragments RemoteEndpoint.Basic sendbinary(bytebuffer part, boolean last) Blocking stream of text RemoteEndpoint.Basic Writer getsendwriter()) Blocking stream of binary data RemoteEndpoint.Basic OutputStream getsendstream() Custom object RemoteEndpoint.Basic sendobject(object customobject) * additional flavors: by completion, by future 22

23 Receiving the Message Whole string MessageHandler.Whole<String> onmessage(string message) Binary data MessageHandler.Whole<ByteBuffer> onmessage(bytebuffer message) String fragments MessageHandler.Partial<String> onmessage(string part, boolean last) Binary data fragments MessageHandler.Partial<ByteBuffer> onmessage(bytebuffer part, boolean last) Blocking stream of text MessageHandler.Whole<Reader> onmessage(reader r) Blocking stream of binary data MessageHandler.Whole<InputSteam> onmessage(inputstream r) Custom object of type T MessageHandler.Whole<T> onmessage(t customobject) 23

24 POJO + Annotations 24

25 Hello World public class HelloBean public String sayhello(string name) { return Hello + name; 25

26 WebSocket Annotations Annotation Level class Turns a POJO into a WebSocket Server class Turns a POJO into a WebSocket Client method Intercepts WebSocket Open method Intercepts WebSocket Close method Intercepts WebSocket Message method parameter Flags a matched path segment of a method Intercepts errors during a conversation 26

27 @ServerEndpoint attributes value Relative URI or URI template e.g. /hello or /chat/{subscriber-level configurator Custom configuration decoders list of message decoder classnames encoders list of message encoder classnames subprotocols list of the names of the supported subprotocols 27

28 Custom value="/hello", encoders={mymessage.class, decoders={mymessage.class ) public class MyEndpoint {... 28

29 Custom Payloads Text public class MyMessage implements Decoder.Text<MyMessage>, Encoder.Text<MyMessage> { private JsonObject jsonobject; public MyMessage decode(string s) { jsonobject = new Json.createReader( new StringReader(s)).readObject(); return this; public boolean willdecode(string string) { return true; // Only if can process the payload public String encode(mymessage mymessage) { return mymessage.jsonobject.tostring(); 29

30 Custom Payloads Binary public class MyMessage implements Decoder.Binary<MyMessage>, Encoder.Binary<MyMessage> { public MyMessage decode(bytebuffer bytes) {... return this; public boolean willdecode(bytebuffer bytes) {... return true; // Only if can process the payload public ByteBuffer encode(mymessage mymessage) {... 30

31 Chat public class ChatBean { Set<Session> peers = Collections.synchronizedSet( public void onopen(session peer) { public void onclose(session peer) { peers.remove(peer);... 31

32 Chat Sample public void message(string message, Session client) { for (Session peer : peers) { peer.getbasicremote().sendobject(message); 32

33 URI Template /orders/{order-id ) public class MyEndpoint public void order-id ) String orderid) {... 33

34 @OnMessage Methods A parameter type that can be decoded in incoming message String, primitive, Reader, ByteBuffer, byte[], InputStream, or any type for which there is a decoder An optional Session parameter Boolean partial flag 0..n String parameters annotated A return type that can be encoded in outgoing message String, primitive, Reader, ByteBuffer, byte[], InputStream, or any type for which there is an encoder 34

35 Java WebSocket Hello World Demo 35

36 Try it Out! 36

37 Resources Specification JSR: jcp.org/en/jsr/detail?id=356 Mailing Lists, JIRA, Archive: java.net/projects/websocket-spec Reference Implementation Tyrus: java.net/projects/tyrus GlassFish: 37