Cometd : Cometd servlet does not support asynchronous on tomcat

• I am working on a Spring-MVC application in which I am currently implementing chat functionality using Cometd on Apache tomcat 7.0.55. I have basic code running and I am able to send messages over channel and receive them too. While the page is loaded I am getting an error that cometd servlet does not support asynchronous operations.
  
  
  
  • As I read the documentation, I found out, it is necessary to configure tomcat with NIO connector, which I have done and also put in web.xml, but still I keep getting that error. Why is that? After looking for some solution, I found one question, that says tomcat needs to be configured, and link for cometd documentation, which inturn only links Apache-tomcat homepage(Dead-End).
  
  
  
  

Can anyone tell me what modifications must I make for allowing websockets. Thanks a lot.

Error log :

SEVERE: Servlet.service() for servlet [cometd] in context with path [] threw exception
java.lang.IllegalStateException: A filter or servlet of the current chain does not support asynchronous operations.
    at org.apache.catalina.connector.Request.startAsync(Request.java:1658)
    at org.apache.catalina.connector.RequestFacade.startAsync(RequestFacade.java:1029)
    at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:379)
    at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:379)
    at org.springframework.security.web.context.HttpSessionSecurityContextRepository$Servlet3SaveToSessionRequestWrapper.startAsync(HttpSessionSecurityContextRepository.java:246)

web.xml :

<servlet>
        <servlet-name>cometd</servlet-name>
        <servlet-class>org.cometd.server.CometDServlet</servlet-class>
        <init-param>
            <param-name>transports</param-name>
            <param-value>org.cometd.websocket.server.WebSocketTransport</param-value>
        </init-param>
        <async-supported>true</async-supported>
    </servlet>
    <servlet-mapping>
        <servlet-name>cometd</servlet-name>
        <url-pattern>/cometd/*</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>cross-origin</filter-name>
        <filter-class>org.eclipse.jetty.servlets.CrossOriginFilter</filter-class>
    <async-supported>true</async-supported>
    </filter>
    <filter-mapping>
        <filter-name>cross-origin</filter-name>
        <url-pattern>/cometd/*</url-pattern>
    </filter-mapping>

Tomcat's conf.xml :

<Connector connectionTimeout="20000" maxThreads="1000" port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" redirectPort="8443"/>

 <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" 
               scheme="https" secure="true" clientAuth="false"  sslProtocol="TLS" maxHttpHeaderSize="8192" connectionTimeout="20000"
               keystoreFile="/home/username/.keystore" keystorePass="password" />

Is there anything else I must do, maybe for 8443 also use NIO protocol? Any help would be nice. Thanks a lot. :-)