Comments on: Is Persistence Ignorance Ignorant?

By: chriscyvas

chriscyvas — Thu, 19 Feb 2009 12:22:16 +0000

I’ve recently had a moment of clarity on all of this and yes, it does make perfect sense. Persistence Ignorance is a good thing.

Thanks for the comments – they prodded me in the right direction.

By: dotnetchris

dotnetchris — Wed, 12 Nov 2008 14:37:42 +0000

I feel the data layer should return POCOs. I loathe working with datasets and any other objects that have tons of semantic garbage in them because the DAL needs it to work right.

PI isn’t just for testability it’s also a key part of Domain Driven Development (DDD) there’s absolutely no reason your business layer should see all of these attributes or other code noise that is required to work with the ORM which is why POCOs are important for a data layer imo.

By: Troy DeMonbreun

Troy DeMonbreun — Tue, 11 Nov 2008 20:23:15 +0000

“So, if you remove TDD from the equation, does Persistence Ignorance still hold water or is it just over-engineering?”

My understanding as to the definition of “Persistance Ignorance” is to allow for the creation POCOs — objects devoid of any infrastructure trappings.

The main advantage of POCOs is the ability to change their backing data stores (different RDBMs, Web Services, REST, etc.) at a future time (or in real-time, for that matter) with no impact on the POCOs themselves.

Often, the idea is to have something like a Infrastructure Service spit out requested POCOs and store provided POCOs.