Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

WebSockets with Spring 4

Talk delivered at Java2Days 2013 on Websocket support in Spring 4 with SockJs and Stomp

Related Books

Free with a 30 day trial from Scribd

See all

WebSockets with Spring 4

  1. 1. WebSockets with Spring 4 Sergi Almar @sergialmar
  2. 2. Who I am • CTO @ Voz.io • Spring Certified Trainer • javaHispano Core Member • Spring I/O conference organiser
  3. 3. Collaborative Apps Multiplayer Games Multimedia Chat Social Feeds Sports Updates Financial Tickets Clickstream Data Online Education Location-based Apps
  4. 4. Real-Time Data on the Web • Polling • Long Polling / Comet • Flash
  5. 5. Problem Applications need two-way communication Too many connections and overhead with ajax / comet
  6. 6. WebSockets
 two-way communication done right
  7. 7. WebSocket Protocol / RFC 6455 • Real-time full duplex communication over TCP • Uses port 80 / 443 (URL scheme: ws:// and wss://) • Small overhead for text messages (frames) • • 0x00 for frame start, 0xFF for frame end (vs HTTP 1Kb) Ping / pong frames for staying alive
  8. 8. WebSocket Handshake 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! client sends a WebSocket handshake request HTTP/1.1 101 Switching Protocols! Upgrade: websocket! Connection: Upgrade! Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=! Sec-WebSocket-Protocol: chat! server response
  9. 9. JS WebSocket API var ws = new WebSocket("ws://www.java2days.com/ws");! ! // When the connection is open, send some data to the server! ws.onopen = function () {! ws.send('Here I am!');! };! ! // Log messages from the server! ws.onmessage = function (event) {! console.log('message: ' + event.data);! };! ! ws.onclose = function (event) {! console.log('closed:' + event.code);! };!
  10. 10. Java WebSocket Implementations • Multiple implementations before the standard • JSR-356 (May 2013) • Reference implementation Tyrus (bundled with Glassfish 4) • Rewrite across containers (tomcat 8.0.0-RC5, Jetty 9.1…)
  11. 11. WebSockets.springify()
  12. 12. Spring WebSockets • WebSockets are now supported in Spring 4 • Fallback options with SockJS • STOMP over WebSocket • Foundation for messaging architecture
  13. 13. WebSocket Handlers public class EchoHandler extends TextWebSocketHandlerAdapter {! ! @Override! public void handleTextMessage(WebSocketSession session, ! ! ! ! ! ! ! ! ! ! ! TextMessage message) throws Exception {! session.sendMessage(message);! }! ! }
  14. 14. WebSocket Config @Configuration! @EnableWebSocket! public class WsConfig implements WebSocketConfigurer {! ! ! ! @Override! public void registerWebSocketHandlers(! ! ! ! ! ! ! ! ! ! WebSocketHandlerRegistry registry) {! ! registry.addHandler(new EchoHandler(), "/echo");! }! }!
  15. 15. Per-Session Handler Previous example showed how to configure a global handler • • but you may want to have a stateful per-session handler @Configuration! @EnableWebSocket! public class WsConfig implements WebSocketConfigurer {! ! ! @Bean! DI public WebSocketHandler echoHandler() {! return new PerConnectionWebSocketHandler(EchoHandler.class);! }! @Override! public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {! registry.addHandler(echoHandler(), "/echo");! }! }
  16. 16. Can anyone join the party? http://caniuse.com/#feat=websockets / DEC 2013
  17. 17. SockJS
 dude, where are my socks?
  18. 18. SockJS • Coherent, cross-browser, Javascript API for full duplex communication. • Close to HTML5 WebSockets API • Client and server side implementation (ruby, node… and also in spring-websockets)
  19. 19. SocksJS API var sock = new SockJS('http://www.java2days.com/ws');! ! sock.onopen = function() {! sock.send('Here I am'); };! ! ! sock.onmessage = function(event) {! console.log('message', e.data);! };! ! sock.onclose = function() {! console.log('close');! };!
  20. 20. SockJS URLs • Base URL: /base_url • Info test: /base_url/info • Session URL: /base_url/server/session
  21. 21. Enabling SocksJS @Configuration! @EnableWebSocket! public class WsConfig implements WebSocketConfigurer {! ! ! ! @Override! public void registerWebSocketHandlers(! ! ! ! ! ! ! ! ! ! WebSocketHandlerRegistry registry) {! ! registry.addHandler(new EchoHandler(), “/echo”).withSockJS();! }! }! MessageHandler doesn’t change (SocketJsService delivers the message to the handler regardless of the protocol)
  22. 22. Problem • WebSockets are too low level and different from HTTP / REST • We need asynchronous, event-driven, reactive programming style • Mmmm, that sounds familiar: JMS, AMQP… 
 but we still want to stick to the Spring MVC programming model
  23. 23. Here’s were we are…
  24. 24. …but we want something like this
  25. 25. Solution • Stomp over WebSocket • Some Spring Integration types have been promoted to the core • • • Message, MessageChannel, MessageHandler… @MessageMapping, @SubscribeEvent… New spring-messaging module
  26. 26. STOMP
  27. 27. STOMP • Simple interoperable protocol for asynchronous messaging • Supported by Apache ActiveMQ, RabbitMQ, HornetQ… • Frames modelled on HTTP var socket = new SockJS('/myapp/echo');! var client = Stomp.over(socket); COMMAND! header1:value1! header2:value2! ! Body^@!
  28. 28. Client Frames • SEND a message • SUBSCRIBE / UNSUBSCRIBE from destination • ACK / NACK the reception of a message (optional by default)
  29. 29. Server Frames • Convey a MESSAGE from subscription to the client • Send RECEIPT when server has successfully processed a client frame • Send an ERROR if something goes wrong
  30. 30. Configuration ! @Configuration! @EnableWebSocketMessageBroker! public class Config implements WebSocketMessageBrokerConfigurer {! ! @Override! public void registerStompEndpoints(StompEndpointRegistry r){! r.addEndpoint("/stomp");! }! ! @Override! public void configureMessageBroker(MessageBrokerConfigurer c){! c.enableSimpleBroker("/topic/");! Subscriptions c.setApplicationDestinationPrefixes("/app");! processed by spring }! ! }! simple broker
  31. 31. Sending Messages stomp.js stompClient.send("/app/trade", {}, JSON.stringify(trade)); prefix SEND! destination:/app/trade! content-type:application/json! content-length:47! ! {"action":"Sell","ticker":"DELL","shares":"10"}! supports ant-style patterns @MessageMapping("/trade")! public void executeTrade(Trade trade, Principal principal) {! ! trade.setUsername(principal.getName());! ! this.tradeService.executeTrade(trade);! }
  32. 32. Handler Methods • Flexible handler method signatures • @PathVariable, @Header/@Headers, @Payload, Message, Principal • Message converters @Controller! public class ChatController {! ! @MessageMapping("/message")! public void sendMessage(String message, Principal principal) {! // ...! }! }!
  33. 33. Handler Methods • Can also return a value ! ! ! Return wrapped in a Message and sent to /topic/message @MessageMapping("/message")! public String sendMessage(String message) {! return message.toUpperCase();! } ! • Or define the destination with @SendTo @MessageMapping("/message")! @SendTo("/topic/spring-room")! public String sendMessage(String message) {! return message.toUpperCase();! }!
  34. 34. Intercepting Subscriptions stompClient.subscribe("/app/positions", function(message) {! ...! });! SUBSCRIBE! id:sub-0! destination:/app/positions! @Controller! public class PortfolioController {! ! @SubscribeEvent("/positions")! public List<Position> getPositions(Principal p) {! Portfolio portfolio = ...! return portfolio.getPositions();! }! } sent directly to the client, not going though the message broker
  35. 35. User destinations • User specific queues can be used • • • /user/** kind of paths queues with unique id will be created Useful to send user related information or errors client.subscribe("/user/queue/private-messages", function(msg) {! // ...! });! ! client.subscribe("/user/queue/errors", function(msg) {! // ...! });!
  36. 36. Sending to user @Controller! public class ChatController {! Will be sent to /user/{username}/queue/message ! @MessageMapping("/message")! @SendToUser! public String sendMessage(String message) {! return message.toUpperCase();! }! ! @MessageExceptionHandler! @SendToUser("/queue/errors")! public String handleException(IllegalStateException ex) {! return ex.getMessage();! }! ! }!
  37. 37. SimpMessagingTemplate • Sending messages without handler methods template.convertAndSend("/topic/chat", message;! template.convertAndSendToUser(user, dest, message;
  38. 38. Using a Message Broker • Previous configuration used Spring’s simple broker • • • Not suitable for clustering Subset of STOMP A message broker can be plugged-in instead
  39. 39. Message Broker Config @Configuration! @EnableWebSocketMessageBroker! public class Config implements WebSocketMessageBrokerConfigurer{! ! @Override! public void configureMessageBroker(MessageBrokerConfigurer c){! c.enableStompBrokerRelay("/queue/", "/topic/");! c.setApplicationDestinationPrefixes("/app");! }! }
  40. 40. Thanks! @sergialmar

×