How to create a websocket endpoint in an existing spring application - spring

Question

I'm trying to make available a new websocket endpoint in an existing spring application.
I'm following the documentation at https://docs.spring.io/spring/docs/4.3.2.RELEASE/spring-framework-reference/html/websocket.html#websocket-server-handler . But based on documentation I should configure the DispatcherServlet or use WebSocketHttpRequestHandler.
How can I make available the websocket endpoint without any change in the web.xml config file ?
This is what I tried, but not working (Client error 404 not found).
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ws="http://jax-ws.dev.java.net/spring/core" xmlns:wss="http://jax-ws.dev.java.net/spring/servlet"
xmlns:websocket="http://www.springframework.org/schema/websocket"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd
http://jax-ws.dev.java.net/spring/core http://jax-ws.dev.java.net/spring/core.xsd
http://jax-ws.dev.java.net/spring/servlet http://jax-ws.dev.java.net/spring/servlet.xsd
http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket.xsd">
<websocket:handlers allowed-origins="*">
<websocket:mapping path="/ws" handler="websocketService"/>
<websocket:handshake-interceptors>
<bean class="org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor"/>
</websocket:handshake-interceptors>
</websocket:handlers>
<bean id="websocketService" class="com.krios.SocketHandler"/>
</beans>
Class file:
public class SocketHandler extends TextWebSocketHandler {
List<WebSocketSession> sessions = new CopyOnWriteArrayList<>();
#Override
public void handleTextMessage(WebSocketSession session, TextMessage message)
throws InterruptedException, IOException {
for(WebSocketSession webSocketSession : sessions) {
Map value = new Gson().fromJson(message.getPayload(), Map.class);
webSocketSession.sendMessage(new TextMessage("Hello " + value.get("name") + " !"));
}
}
#Override
public void afterConnectionEstablished(WebSocketSession session) throws Exception {
//the messages will be broadcasted to all users.
sessions.add(session);
}
}

Answer 1

I can provide you the java configuration (you can then change it to xml yourself or use it as java class and scan it from xml)
#Configuration
#EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
#Bean
public MessagingWebSocketHandler webSocketHandler() {
//handler of your websocket. should be a class implementing WebSocketHandler.
//You could also extend AbstractWebSocketHandler or TextWebSocketHandler and override methods
return new MessagingWebSocketHandler();
}
#Bean
public WebSocketContainerFactoryBean createWebSocketContainer() {
WebSocketContainerFactoryBean container = new WebSocketContainerFactoryBean();
container.setMaxTextMessageBufferSize(StaticConfig.MAXIMUM_WS_TEXT_BUFFER_SIZE);
container.setMaxBinaryMessageBufferSize(StaticConfig.MAXIMUM_WS_BINARY_BUFFER_SIZE);
container.setMaxSessionIdleTimeout(StaticConfig.MAXIMUM_WS_SESSION_IDLE_TIMEOUT);
container.setAsyncSendTimeout(StaticConfig.MAXIMUM_WS_ASYNC_SEND_TIMEOUT);
return container;
}
#Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry webSocketHandlerRegistry) {
webSocketHandlerRegistry.addHandler(webSocketHandler(), "/message").setAllowedOrigins("*"); // you could also get handler from context
}
}
I hope it hepls.
update
I myself don't use xml based configuration. But the simplest way is to add this java code then scan it from xml. For example, by adding this line to your spring servlet configuration xml you can scan your configuration package or whole project package.
<context:component-scan base-package="com.my.company.config" />
Then your WebSocketConfig class must be under com.my.company.config
Documentation Of Websocket support and configuration is here. On section Create and Configure a WebSocketHandler you can read about xml configuration. I havent test it myself tho.