Do I need to use DDD, Unit of Work, Repositories or something similar for simple web apps?

Question

I'm working on a simple eCart system using .net4 (c#). I've been doing a lot of reading about Unit of Work Pattern, Repository Pattern, and Persistence Ignorance. I think I have a grasp on the strategy and benefits to building my layers this way, but for my simple app I'm wondering if it's necessary and if anyone can point me towards good architecture for my scope.

Please correct me if I'm wrong - the main benefits to using repositories are to create fewer trips to the DB and to separate application architecture from DB architecture. IE - what's good for DB performance isn't always good for application design so it's best to design what's best for both and then create an interface between the two.

So here's the question - I want any business transaction that occurs to be saved to the DB as soon as it occurs, so there doesn't seem to be a point in queuing data in repositories and then saving it immediately. Why not just save it directly?

Are there other benefits of DDD that I'm missing or would it be over engineering to build out such a robust architecture for every simple project that comes along? Thanks for any help.

Answer 1

Do you need to use [insert pattern here]: Nope When it comes right down to it, the best practice is always the one that gets your application done, and meets the time, monetary, and technical requirements.

But if you take the "lets just get it done" approach, then be aware of the Technical Debt you might be incurring.

Also there are a lot of reasons to use some of these patterns (and they don't always have to do with performance), particularly the Unit Of Work pattern. This has more to do with the requirements and restrictions that often come with ORM's and such. These issues can be a bit complex, but I suspect as you begin to implement some of these things you'll start to realize what those issues are and come to understand why these patterns are useful.

Answer 2

Agree with CodingGorilla. Patterns are great unless they conflict with YAGNI.

If every transaction needs to be written immediately (that is, if you have potential contention between the actions of two users) then you will need a queuing mechanism or you can use the underlying transactional mechanism of whatever data repository you might be using (e.g. SQL)