Duck Typing an Invoice?

Has the nature of data modeling changed in the era of the Semantic Web?

All around the world, as I write this, developers are struggling to create models for invoices and other "simple" business documents into IT systems. All around the world, multiple efforts new and old continue to attempt to zoom in on a definitive model of what it is to be an invoice...

There is *no such thing as an invoice* in the classical data modelling sense... There seems to me to be a fundamental mismatch here between the classical software model of an invoice and the reality of real world invoices.

Think back to how you recognized that invoice as an invoice. You found a bunch of attributes which you associate with invoices. You found enough of them in your analysis of the piece of paper to conclude that it was statistically speaking, more likely than not to be an invoice. It if walks like a duck...

I think this is a case of both/and rather than either/or. Financial systems should not be expected to "scan a document looking for invoice-y-ness".

Yes, there are umpteen definitions of an invoice. No, formally modelling any one of these is not an endless excercise.

You see, any given accounts payable system only has to understand *one* of these. So the one I use understands SAP's definition of an invoice. The one you use may understand Great Plain's definition.

Will there ever be a universal definition of "Invoice" for the Internet? Or will the Semantic Web just allow us to send bits that resemble invoice-y-ness?

I'm not sure we'll need universality. I kind of anticipate the arrival of a marketplace for "adapters" and "translators" for documents, and some of those will employ fuzziness. There is room for formal documents to become more "semi-formal" making them more "social". But most of today's formal bits for formal systems, like subledgers of purchasing systems, must remain formal.

My AP system does not need a universal model, nor does it need to understand umpteen invoice models, but neither does it need a neural net or a rule base. It does need at least one formal definition of an invoice, which obviously is not insurmountable.

Maybe I'm a quack.