using the webmethod in asp.net

[WebMethod]
 static public string UpdateUser(string roomID)
{
     try
     {
         ChatRoom room = ChatEngine.GetRoom(roomID);
         if (room != null)
         {
             string res = "";
             if (room != null)
             {
                 string s = string.Empty;
                 //if ((HttpContext.Current.Session["list"] != null) && (HttpContext.Current.Session["list"] != ""))
                 //{
                 //    s = HttpContext.Current.Session["list"].ToString();

                 //    foreach (char data in s)
                 //    {
                 //        if (data == Convert.ToChar(HttpContext.Current.Session["UserName"]))
                 //        {
                 //            res = room.UpdateUser(HttpContext.Current.Session["UserName"].ToString(), data);
                 //        }
                 //    }
                 //}
                 //else
                 //{

                     res = room.UpdateUser(HttpContext.Current.Session["UserName"].ToString());
                     string dataset3 = rid;
                     ChatRoom room1 = ChatEngine.GetRoom(dataset3.ToString());
                   string  prevMsgs = room1.JoinRoom1(HttpContext.Current.Session["UserName"].ToString(), HttpContext.Current.Session["UserName"].ToString());

                     string dataset = string.Empty;
                     Clslogin clslogin = new Clslogin();
                        DateTime  ds1 = DateTime.Now.Date;
                        string ds = ds1.ToString("MM/dd/yyyy") + " " + DateTime.Now.Hour + ":" + DateTime.Now.Minute;
                     if ((HttpContext.Current.Session["UserName"] != null) || (HttpContext.Current.Session["UserName"] .ToString()!= ""))
                     {
                         int userid=Convert.ToInt32(clslogin.groupuserid(HttpContext.Current.Session["UserName"].ToString()));
                         dataset = clslogin.usermessage(userid, ds, rid.ToString());
                         if (dataset != "")
                         {

                             HttpContext.Current.Response.Redirect("individual.aspx?Channel=" + rid.ToString() + "&User=" + HttpContext.Current.Session["UserName"].ToString() + "", false);
                             HttpContext.Current.ApplicationInstance.CompleteRequest();
                             //HttpContext.Current.Response.Write("<script type='text/javascript'>detailedresults=window.open('individual.aspx?Channel=" + rid.ToString() + "&User=" + HttpContext.Current.Session["UserName"].ToString() + "',null,'height=300,width=600,resizable=no,scrollbars=no,titlebar=no,status=no,toolbar=no,menubar=no,channelmode=no');</script>");
                         }
                         else
                         {

                         }
                     }
                     else
                     {

                     }
                 //}
             }

             return res;
         }
     }
     catch (Exception ex)
     {

     }
     return "";
 }