Data Driven Development

So we have Test Driven Development and Model Driven Development or Design by Contract (similar perspective). But in the past, I've been a fan of Data Driven Development. This is a technique I haven't had the pleasure of using recently....because it relies on you building new applications with new databases.

What is this technique you ask? Well for me it is designing the data model first. In the early days of Client/Server, PowerBuilder and ERwin were my tools of choice. New applications. New databases. My design process (and that of many of my associates) was not so much to design a database but to document the data that existed in the organization - and do that in 3rd normal form. ERwin still stands as one of the best modeling tools ever because it actually made the job of coding up a database schema easier and faster than any other alternative. I could also use my model throughout the entire lifecycle since it did an excellent job at full round trip engineering/synchronization.

One of the cool features of PowerBuilder was your ability to annotate your database schema with UI hints. So you could say that a given column in your database should by default be shown as a checkbox, and that checked should be saved as “true“ and unchecked as “false“ - or whatever weird thing your DBA said it had to store. Whenever you designed a screen with that column, bam you'd have it the way you'd expect - as a checkbox. The downside of PowerBuilder's datawindows of course was that the data store/entity/container was quite pretty tied to your database and they made no attempts to hide that fact. But boy, productivity was really high - although I was producing tightly coupled, loosely coupled code :( .NET let's me build better code now, but productivity is still lacking.

At TechEd a couple of weeks ago, I stopped by the DeKlarit booth for a demo of their product by their lead architect Andres Aguiar. I was happy to see a tool that builds upon the Data Driven Development process. Of course, you don't have to start with an empty database, but this tool does an excellent job of making your job easy when starting from scratch. Andres promised to send me an eval so I can play with it some more to see how it works with existing databases but this tool so stay tuned. I could easily see this tool paying for itself in a matter of a couple of weeks.

As for ERwin, I'm still a fan although it really hasn't changed much in the past 10 years. I remember the first copy I had fit on a single floppy. So did the 200 table model I created with it. I was using LBMS System Designer who stored my model in some kind of 10mb black hole and took 10 minutes to generate a schema. When I first installed ERwin, I had it installed and reverse engineered by LBMS model - and forward engineered to from Oracle to SqlServer inside of 10 minutes. I couldn't believe the schema generation took 20 seconds compared to LBMS at 10 minutes.