Dwr Session Error A request has been denied 错误

Dwr Session Error A request has been denied 异常
用dwr时报Session Error A request has been denied ...... 异常：
解决方法如下
在web.xml中的Servlet添加两个初始化参数参数内容如下

     <servlet>  
           <init-param>     
                  <param-name>crossDomainSessionSecurity</param-name>     
                  <param-value>false</param-value>     
          </init-param>
          <init-param>
                 <param-name>allowScriptTagRemoting</param-name>
                 <param-value>true</param-value>
          </init-param>
     </servlet>  


  重新启动一下服务这个问题就解决了。