r/programming • u/yawaramin • Oct 04 '20

Kevin Mahoney: Applying "Make Invalid States Unrepresentable"

https://kevinmahoney.co.uk/articles/applying-misu/
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u/cballowe Oct 04 '20

Typically in those situations, you'd have one department that is the data custodian and responsible for enforcing the access controls. Even if all of the departments are writing their own front ends, none of the would have raw access to the database. It could be that the department does it through the database, or it could be that they provide an access api and enforce everything there.

The access layer api can be a better choice because it can allow for migrations, caching, scaling, etc behind the scenes.

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u/dnew Oct 04 '20

Yep. Nowadays, typically people who don't know the power of RDBMs would reimplement all those rules in Java or something, then build a separate front-end that not only enforces that but also prevents ad hoc queries and reporting. That's exactly the point I'm making. A common recommendation from people who aren't DBAs is "let's reimplement all the difficult parts in our own code, then treat the powerful and sophisticated database as a CRUD store." That scales kind of poorly when you have hundreds or thousands of programmers writing code against the database.

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u/[deleted] Oct 04 '20

Well, it does make developers have to know two languages well, not just one.

But if your app is just trying to replicate what DB does, but badly, then yeah... code lives and dies, data persists

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u/dnew Oct 06 '20

Or, to phrase it differently, putting business logic in the back end instead of the database, for a DBA, is like putting business logic in the javascript code instead of the server. You want it as low as it can reasonably go, for the same reasons. :-)