Y.M. Y.M. - 3 months ago 119
Java Question

Springboot @ServerEndPoint "Failed to find the root WebApplicationContext."

I'm having trouble using spring with @ServerEndPoint annotated class

i'm using Springboot 1.2.3 and i'm trying to figure it out how to have a single instance of the endpoint

@SpringBootApplication
@EnableJpaRepositories
@EnableWebSocket
public class ApplicationServer {
public static void main(String[] args) {
SpringApplication.run(ApplicationServer.class, args);
}
}


Spring configuration:

@ConditionalOnWebApplication
@Configuration
public class WebSocketConfigurator {

@Bean
public ServerEndPoint serverEndpoint() {
return new ServerEndPoint();
}

@Bean
public ServerEndpointExporter serverEndpointExporter() {
return new ServerEndpointExporter();
}
}


WebSocket endpoint:

@ServerEndpoint(value = "/", decoders = MessageDecoder.class,
encoders = MessageEncoder.class, configurator = SpringConfigurator.class)
public class ServerEndPoint {

private static final Logger LOG = LoggerFactory.getLogger(ServerEndPoint.class);

public static final Set<CommunicationObserver> OBSERVERS = Sets.newConcurrentHashSet();

@OnMessage
public void onMessage(Session session, Message msg) {
LOG.debug("Received msg {} from {}", msg, session.getId());
for (CommunicationObserver o : OBSERVERS) {
o.packetReceived(session, msg);
}
}


This is based on the Spring WebSocket JSR-356 tutorial, but i've got the following error:

java.lang.IllegalStateException: Failed to find the root WebApplicationContext. Was ContextLoaderListener not used?
at org.springframework.web.socket.server.standard.SpringConfigurator.getEndpointInstance(SpringConfigurator.java:68)
at org.apache.tomcat.websocket.pojo.PojoEndpointServer.onOpen(PojoEndpointServer.java:50)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.init(WsHttpUpgradeHandler.java:138)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)


I have both tested in embedded mode and with external tomcat 8 and jetty 9 (in external mode, i remove de Spring config file) but the same error appeares.

the only workaround i've found is to create a custom configurator.

public class SpringEndpointConfigurator extends ServerEndpointConfig.Configurator {

private static WebApplicationContext wac;

public SpringEndpointConfigurator() {
}

public SpringEndpointConfigurator(WebApplicationContext wac) {
SpringEndpointConfigurator.wac = wac;
}

@Override
public <T> T getEndpointInstance(Class<T> endpointClass) throws InstantiationException {
T endPoint = wac.getAutowireCapableBeanFactory().getBean(endpointClass);
return (endPoint != null) ? endPoint : wac.getAutowireCapableBeanFactory().createBean(endpointClass);
}


it is created as a @Bean with the parameterized constructor.

I must have missed something to get it done with the SpringConfigurator class, but i don't know what.

Answer

thanks to Sergi Almar and his answer, i have managed to use the Spring implementation instead of the javax.websocket implementation:

public class SpringWebSocketHandler extends TextWebSocketHandler {

    private final Set<CommunicationObserver> observers = Sets.newConcurrentHashSet();

    @Autowired
    private MessageContext mc;

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        Message msg = mc.parse(message.getPayload());

        for (CommunicationObserver o : observers) {
            o.packetReceived(session, msg);
        }
    }
}

Config file:

@ConditionalOnWebApplication
@Configuration
public class WebSocketConfigurator implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myHandler(), "/").setAllowedOrigins("*");
    }

    @Bean
    public SpringWebSocketHandler myHandler() {
        return new SpringWebSocketHandler();
    }
}

Note that the setAllowedOrigins("*") was mandatory for me because when using the java client, i had the following error:

org.springframework.web.util.WebUtils : Failed to parse Origin header value [localhost:8080]

Also note that the MessageContext was used to parse/format strings instead of MessageEncoder/Decoder classes (they inherited from MessageContext).

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