silk and spinach

In one of last week’s architecture workshops (see databases as life-support for domain objects) our group briefly considered how the new product line might emerge gradually from a series of user stories. The Product Owner agreed that stories about persistence would probably be placed relatively far down the backlog, behind the stories that deliver the first several tranches of usable business value. The Product Owner wants to see and understand the business logic first, and only later will he care about “non-functionals” such as persistence and levels of service.

So if we truly design and build our application story by story, without being tempted to predict what the Product Owner will want in the future, then the database will not exist until after many of the domain objects. This is business-level support for J.B’s assertion that the database should be developed last. And it knocks sideways the idea that the ‘architecture’ should be designed at the start of a project.