Three-tier web applications with toplink

Question

I'm looking for patterns people have used with TopLink for building web applications that employ the following typical usage scenario:
- the application loads an object (using one UOW)
- the object is passed up to the UI tier (i.e., browser)
- some modifications are made to the object (via browser form submission)
- the object is passed back down to the business logic tier
- the application persists these modifications (in a second UOW)
Because this scenario spans two requests, each using a separate thread, the same UOW (nor the same session)cannot be used for both the read and write.
So far, the best approach to doing this in TopLink that I've come up with is the following:
- my application reads the object in a UOW.
- it registers the object to get a working clone.
- my app commits the UOW, but keep the clone
- the clone is passed to the UI tier
- UI layer modifies clone and returns to business logic tier
- my app reads the object again in a new UOW
- the new object is registered
- the changes in clone are incorporated into the uow via the mergeClone method
- the changes are committed
it works, but it clearly violates some of the intentions of the framework.
Can anyone recommend a better way to handle this scenario?
Thanks,
Derek

Answer 1

The first two tiers are analoguous to what Aperture
gives you: and index page and then a detail page with
a larger version of the photo and various EXIF
information.
However, I also had the option to export the
full-size photo as well, which was linked to clicking
the larger photo (or an explicit link). This was good
so people could get the big picture to print or
otherwise further manipulate.
This is exactly what I am looking for as well (would be satisfied with two-tier, though, just a thumbnail and a link to the hires image).
I already started a thread with my findings here: http://discussions.apple.com/thread.jspa?threadID=455157 but didn't find any further info yet. A documentation on the tags used for building the web gallery templates would probably help a lot.
Any help appreciated