[Zope] CatalogAware & Catalog.

Hello, I would like to know if it is possible to update "only" the new document instead of update the whole or update only specific type of object. I have tried with CatalogAware (i select CatalogAware as the base-class when I create a new type of Zclass.) but I still cannot keep track new document of that document type. I have to update my catalog manually every time I add the new document. From Zope Book about catagolizing content, it should work out but it didn't. I guess I did something wrong. When I add the new document, how the Catalogaware work? Besides, I wonder if we can set the timer (maybe from the machine or system) for updating catalog automatically? Thank you in advance for any answer. pattreeya.