public void HelloWorld()
    {
        var Lista = new List<Atributos>();
        using (var con = new SqlConnection(cnn))
        {
            var cmd = new SqlCommand("SELECT * FROM ASIGNATURA", con);
            con.Open();
            var dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                var hambre = new Atributos
                {
                    iD = Convert.ToInt32(dr[0].ToString()),
                    Nombre = dr[1].ToString(),
                    Credito = Convert.ToInt32(dr[2].ToString())

                };
                Lista.Add(hambre);
            }
        }
        var js = new JavaScriptSerializer();
        Context.Response.Write(js.Serialize(Lista));
    }