DataSet ds = null;
        //defining cache variable
        ds = (DataSet)Cache["ds1"];
        if (ds == null)
        {
            ds = new DataSet();
         //reading xml file
            ds.ReadXml(Server.MapPath("product.xml"));
     //defining cachedependency object based on filename
            CacheDependency obj = new CacheDependency(Server.MapPath("product.xml"));
     //populating cache with value ("key",value,cachedependency object)
            Cache.Insert("ds1", ds, obj);
            Response.Write("dataset from xml...");
        }
        else
        {
            Response.Write("from cache....");
        }
        //binding the data base schema & data  
        GridView1.DataSource = ds.Tables["product"];
        GridView1.DataBind();