Tonight I found myself wondering in Wegmans, an incredibly overstocked and expensive supermarket, waiting for my wife to finish shopping while I mulled over some design quandaries having to do with our current project.

We're trying to match our existing object model with RDF, since we'd like to leverage as much of the power of RDF and related technologies as we can. Why build when you can borrow? Besides, we'd like to integrate with the world, both now and in the future. That's the point of standards, yes?

So, here I am, using a supermarket as a development example. Two primary concepts from our model include "items" and "tags". Sure enough, there were plenty of items, with tags, scattered all over those shelves. Now don't get me wrong, we're not writing a supermarket inventory program. I was just trying to visualize the breadth of the model, using soup cans and price tags as visual aids.

The problem with meta-models (and meta-meta-models) is that they make my head hurt. It's all but impossible to keep it straight. "Okay, a red delicious apple is a kind of apple, which is a kind of fruit, which is a kind of food." Meanwhile people are staring at me as I walk aimlessly, muttering while I scan the aisles, clearly not shopping.

"Now grape juice has a closer ... semantic proximity ... to sparkling cider than it does to pretzels, but how do you represent that in RDF?" Parents take their children by the hand and leave my aisle (yes, I'm exaggerating).

"So is a tag a predicate? Is the act of affixing this rectangular cardboard to this withering poinsetta the same as making an RDF statement, with the poinsetta the resource and the predicate the tag?" Stock clerks, unlucky enough to get the New Year's Day shift, watch me cautiously.

"Or is the tag a resource? Yes, it must be. Look, it has properties: price, discount status, bonus card points. And what about that UPC code.... yes, the UPC code. Now that's a URI if I ever saw one." I'm now becoming aware that I must look a little odd, as I'm carrying nothing, have no cart, and have been wondering the nearly empty store for twenty minutes.

My wife finally returns and we check out. Driving home, I ponder the problem, now using street signs and license plates as my visual aids.

Clearly I need a break from this meta madness. A good couple days dealing with actual things. Fat chance.