Web sockets in Java
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The document discusses WebSocket in Java, including: 1. WebSocket is a protocol providing full-duplex communications over a single TCP connection and was standardized by IETF as RFC 6455. 2. Sample WebSocket applications are demonstrated using the JavaWebSocket library, Java EE 7 with Tomcat, and Spring 4 with SockJS for fallback support to older browsers. 3. Code snippets show how to set up WebSocket servers and handlers in each approach to handle connections, messages, and disconnections from clients.
![public static void main(String[] args)
JavaWebSocket (web-socket-samples/javawebsockets)
public class Main extends WebSocketServer {
public Main() {
super(new InetSocketAddress(8887));
}
@Override
public void onOpen(WebSocket conn,
ClientHandshake handshake) {
//Handle new connection here
conn.send(“{”connected”: true}”);
}
@Override
public void onMessage(WebSocket conn,
String message) {
//Handle client received message here
}
* https://github.com/TooTallNate/Java-WebSocket
@Override
public void onClose(WebSocket conn, int code,
String reason, boolean remote) {
//Handle closing connection here
}
@Override
public void onError(WebSocket conn,
Exception exc) {
//Handle error during transport here
}
public static void main(String[] args) {
Main server = new Main();
server.start();
}
}
Netcetera | 4](https://image.slidesharecdn.com/websocketsinjava-131223055258-phpapp01/85/Web-sockets-in-Java-4-320.jpg)
![Spring4
Static dispatcher servlet config
public class DispatcherServletInitializer extends
AbstractAnnotationConfigDispatcherServletInitializer{
@Override
protected Class<?>[] getRootConfigClasses() { return null; }
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class<?>[] {WebConfig.class};
}
@Override
protected String[] getServletMappings() { return new String[]{“/”}; }
@Override
protected void customizeRegistration(Dynamic registration) {
registration.setInitParameter(“dispatchOptionsRequest”, “true”);
}
}
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Web sockets in Java
- 1. WebSockets in Java From n00b to pro 22 Dec 2013, JavaDay, Pance Cavkovski
- 2. Theory - WebSocket is a protocol providing full-duplex communications over a single TCP connection. - Standardized by IETF as RFC 6455 - Designed to be implemented in web browsers and web servers - HTTP Upgrade request for initiating connection * Contents from Wikipedia: http://en.wikipedia.org/wiki/Web_sockets GET /mychat HTTP/1.1 Host: server.example.com Upgrade: websocket Connection: Upgrade Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw== Sec-WebSocket-Protocol: chat Sec-WebSocket-Version: 13 Origin: http://example.com HTTP/1.1 101 Switching Protocols Upgrade: websocket Connection: Upgrade Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk= Sec-WebSocket-Protocol: chat Netcetera | 2
- 4. public static void main(String[] args) JavaWebSocket (web-socket-samples/javawebsockets) public class Main extends WebSocketServer { public Main() { super(new InetSocketAddress(8887)); } @Override public void onOpen(WebSocket conn, ClientHandshake handshake) { //Handle new connection here conn.send(“{”connected”: true}”); } @Override public void onMessage(WebSocket conn, String message) { //Handle client received message here } * https://github.com/TooTallNate/Java-WebSocket @Override public void onClose(WebSocket conn, int code, String reason, boolean remote) { //Handle closing connection here } @Override public void onError(WebSocket conn, Exception exc) { //Handle error during transport here } public static void main(String[] args) { Main server = new Main(); server.start(); } } Netcetera | 4
- 5. Client JavaScript WebSocket API var socket = new WebSocket(“ws://localhost:8887”); socket.onopen = function() { //event handler when the connection has been established socket.send(nickname); }; socket.onmessage = function(message) { //event handler when data has been received from the server alert(message.data); }; socket.onclose = function() { //event handler when the socket has been properly closed } socket.onerror = function() { //event handler when an error has occurred during communication } Netcetera | 5
- 6. Java EE 7: JSR 356 + Java7 Tomcat (>7.0.43) (web-socket-samples/eesockets) @ServerEndpoint(“/chat”) public class EESocketChatEndpoint { @OnOpen public void onOpen(Session session) { //Handle new connection here session.getBasicRemote() .sendText(“{”connected”: true}”); } @OnMessage public void onMessage(String message) { //Handle client received message here } @OnClose public void onClose(Session session, CloseReason reason) { //Handle closing connection here } @OnError public void onError(Session session, Throwable throwable) { //Handle error during transport here } } * JSR 356, Java API for WebSocket: http://www.oracle.com/technetwork/articles/java/jsr356-1937161.html (javax.websocket.*) Netcetera | 6
- 7. Client Pretty much the same JavaScript WebSocket API var socket = new WebSocket(”ws://” + document.domain + “:8080/eesockets/chat”); socket.onopen = function() { //event handler when the connection has been established socket.send(nickname); }; socket.onmessage = function(message) { //event handler when data has been received from the server alert(message.data); }; socket.onclose = function() { //event handler when the socket has been properly closed } socket.onerror = function() { //event handler when an error has occurred during communication } Netcetera | 7
- 8. Spring4 Static dispatcher servlet config public class DispatcherServletInitializer extends AbstractAnnotationConfigDispatcherServletInitializer{ @Override protected Class<?>[] getRootConfigClasses() { return null; } @Override protected Class<?>[] getServletConfigClasses() { return new Class<?>[] {WebConfig.class}; } @Override protected String[] getServletMappings() { return new String[]{“/”}; } @Override protected void customizeRegistration(Dynamic registration) { registration.setInitParameter(“dispatchOptionsRequest”, “true”); } } Netcetera | 8
- 9. Spring4 Static context config @Configuration @EnableWebMvc @EnableWebSocket @ComponentScan(basePackages={“mk.hsilomedus.springsockets.service”}) public class WebConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer { public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { registry.addHandler(chatWenSocketHandler(), “/chat”).withSockJS(); } @Bean public WebSocketHandler chatWebSocketHandler() { return new PerConnectionWebSocketHandler(ChatWebSocketHandler.class); } @Override public void configureDefaultServletHandling(DefaultServerHandlerConfigurer configurer) { configurer.enable(); } Netcetera | 9 }
- 10. Spring4 WebSocketHandler (web-socket-samples/springsockets) public class ChatWebSocketHandler extends TextWebSocketHandler { @Override public void afterConnectionEstablished( WebSocketSession session) { //Handle new connection here session.sendMessage( “{”connected”: true}”); } @Override public void handleTextMessage( WebSocketSession session, TextMessage message) { //Handle message.getPayload() here } * http://blog.gopivotal.com/products/websocket-architecture-in-spring-4-0 @Override public void afterConnectionClosed( WebSocketSession session, CloseStatus status) { //Handle closing connection here } @Override public void handleTransportError( WebSocketSession session, Throwable exception) { //Handle error during transport here } } Netcetera | 10
- 11. Client SockJS //I can now fallback to longpoll and do IE9!!! var socket = new SockJS(”http://” + document.domain + “:8080/springsockets/chat”); socket.onopen = function() { //event handler when the connection has been established socket.send(nickname); }; socket.onmessage = function(message) { //event handler when data has been received from the server alert(message.data); }; socket.onclose = function() { //event handler when the socket has been properly closed } socket.onerror = function() { //event handler when an error has occurred during communication } Netcetera | 11
- 12. socket.close(); Thanks for your attention - The whole source code is available on github: https://github.com/hsilomedus/web-sockets-samples - /javawebsockets – with the JavaWebSocket library - /eesockets – with Tomcat 7.0.47 - /springsockets – with Spring4 RC2 and Tomcat 7.0.47 - All three are eclipse projects running on Java7 - Questions? - https://twitter.com/hsilomedus, http://hsilomedus.me/ Netcetera | 12