NullPointerException while accessing request struts2

[Rohit]

Hi,

I am facing a strange error in Struts2, I am getting a null pointer
exception when trying to set attribute into request scope,

Struts Problem Report

Struts has detected an unhandled exception: Messages:
File: org/apache/catalina/connector/Request.java Line number: 1,424
Stacktraces java.lang.NullPointerException

org.apache.catalina.connector.Request.setAttribute(Request.java:1424)
org.apache.catalina.connector.RequestFacade.setAttribute(RequestFacade.java:
503)
javax.servlet.ServletRequestWrapper.setAttribute(ServletRequestWrapper.java:
284)
com.inrev.bm.action.IRBrandMgmtAction.wrdTwts(IRBrandMgmtAction.java:81)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)

My code is given below,

public class IRBrandMgmtAction extends ActionSupport implements
SessionAware,ServletRequestAware {


private static final long serialVersionUID = 1L;

private Map session;

private HttpServletRequest request; 

private IRWordToTrack wrdtotrack;

private IRBrandMgmtDAO brandMgmtDAO;

private static org.apache.log4j.Logger log =
Logger.getLogger(IRBrandMgmtAction.class);

and the method where this is happening,

public String wrdTwts()
{
    ArrayList<IRBrandTrackBean> messages = null;
    IRDateUtil dtUtil = new IRDateUtil();
    String wordId = request.getParameter("wordId");

    IRUser user = (IRUser) session.get("user");
    IRWordToTrack word = brandMgmtDAO.getWord(Integer.parseInt(wordId));

    if(word!=null)
    {
        messages =
brandMgmtDAO.viewMsgForUser(word.getWord().toUpperCase().trim(), null,
dtUtil.getTimeZoneOffset(user.getTimeZone()));
    }

    request.setAttribute("messages",messages);

    return "tweets";
}

I am using tomcat 6 server.

Regards, Rohit