Comment by simiones

My experience is that all of these layers have identical data models when a project begins, and it seems like you have a lot of boilerplate to repeat every time to describe "the same thing" in each layer.

But then, as the project evolves, you actually discover that these models have specific differences in different layers, even though they are mostly the same, and it becomes much harder to maintain them as {common model} + {differences}, than it is to just admit that they are just different related models.

For some examples of very common differences:

- different base types required for different languages (particularly SQL vs MDW vs JavaScript)

- different framework or language-specific annotations needed at different layers (public/UNIQUE/needs to start with a capital letter/@Property)

- extra attached data required at various layers (computed properties, display styles)

- object-relational mismatches

The reality is that your MDW data model is different from your Database schema and different from your UI data model (and there may be multiple layers as well in any of these). Any attempt to force them to conform to be kept automatically in sync will fail, unless you add to it all of the logic of those differences.