public class UrlRewrite : IHttpHandler
    {
        
        #region IHttpHandler Members

        public bool IsReusable
        {
            get { return false; }
        }

        public void ProcessRequest(HttpContext context)
        {
            string currentPath = context.Request.Url.PathAndQuery;
            

            Regex reg = new Regex("/extend/(?<user>)([A-Za-z0-9]+).aspx(.*)");
            if (reg.IsMatch(currentPath))
            {
                string url = reg.Replace(currentPath, "/default.aspx?user=$1");
                context.RewritePath(url);
            }
            
        }

        #endregion
    }