January 24, 2003 spout

OOD (The D Stands for Dead In The Water”)

Reading a very interesting book which I’ll discuss in a future post, I came to a startling conclusion. As much as I love OO thinking and programming, OO databases are never going to fly. I realize that this may not be so startling considering how long OOD products have existed and how unsuccessful they’ve been so far, but the conclusion I came to was *why* they’ll never fly. The reason is simple: the data itself is more valuable than the programs that use it.

For an OO guy, taught that behavior was everything and data was an implementation technique, that’s a startling conclusion. However, the beauty of a database is that it’s devoid of behavior, or, if there is behavior, it’s layered in on top of the data. Programming languages come and go along with the ideas that underlie them and the applications that are built with them. Relational data, on the other hand, is a model that’s simple enough, but complete enough, to move forward from application to application, accumulating value as you go in the data itself. And, since the relational model is so entrenched, no technology for the last 10 years or the next 1000 would be complete without support for it. Even Microsoft, IBM, GM and AT&T will prove to be less enduring than relational data, the tools to program against it and the tools to slice and dice it w/o programming anything (the latter are amazing strong already and continue to grow).

Data in OO databases, on the other hand, are bound to behavior and worthless for anything but the limited set of applications for whom the behavior was paramount and the data an implementation detail. When things change, as they always do, how are you going to get the data out so you can do things different? You’re going to dump it to the simplest, most complete, most firmly entrenched data format that the world has every known — relational data.

OO persistence formats are, by their natural, tied to a specific object model and therefore hopelessly proprietary. And with the emergence of XML, OO persistence formats are going the way of the dodo, even for applications running on machines without a database server. Why would I persist data to a closed format when I can choose relational data for the big stuff and XML for the small stuff? Both provide endless tools for slicing and dicing and bringing forward when the application dies. With OO persistence, when the app goes, so goes the data. The problem with OOD is that things are *too* seamlessly integrated. Ironic, no?