xalan-j2 D7: StreamSource cannot be kept?

Hi, I was hoping someone could help me with this problem.

I keep the XSL and XML StreamSource's for my webapp in a couple of java
objects on a j2ee compliant servlet container. When I want to transform a
page I request the appropriate combination of StreamSource's (see More info
on the backend below).  Everything works fine THE FIRST TIME.  If I use the
browser back button and perform the exact same action to get to the same
page that origanlly worked, it produces a TransformerException saying that
it cannot find the file specified (but it's already setup as a stream...).
Nothing has changed. If I check the StreamSource's reference ID, it has not
changed.  Has something changed the stream itself? Is there some way to see
the stream?

More info on the backend:
-----------------------------------
I was hoping (don't know if it is a good thing to do or not...?) to create a
"database" of StreamSources - with an instance of a Page Object containing
the StreamSource for an XML.  A Site Object contains the XSL StreamSource's.
To get a page I access the appropriate instances and get the XSL and XML
StreamSources. Can anybody help or give me some advice? Is this a good
strategy for producing a fast, dynamic site?

Thanks,
Rob


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list