Question

When I look at ASP.NET MVC projects I everytime see loose coupled architecture.

For what do I need a loose coupling in a web architecture (if I do not make unit tests)?

What are advantages and disadvantages of this?

What is the main reason to decouple layers/classes?

What if I do not want to change my DAL for example? I mean when shall I change my whole DAL?! So I could couple my DAL to the UI. What is bad with this?

Answer 1

It will save you a lot of time for any project that isn’t trivially small, where I define trivially small as less than a couple thousand lines of code (depending on the language).

The reason is that once you get past super small projects, each change or update gets harder the more tightly coupled it is. Being loosely coupled enables you to keep moving forward, adding features, fixing bugs, etc.

At a certain point I think any program becomes a nightmare to maintain, update and add on to. The more loosely coupled the design is, the further that point is delayed. If it’s tightly coupled, maybe after about 10,000 lines of code it becomes unmaintainable, adding some features become impossible without essentially rewriting from scratch.

Being loosely coupled allows it to grow to 1,000,000 – 10,000,000 lines of code while still being able to make changes and add new features within a reasonable amount of time.

These numbers aren’t meant to be taken literally as they’re just made up, but to give a sense of where it becomes helpful.

If you never need to update the program and it’s fairly simple then sure, it’s fine to be tightly coupled. It’s even okay to start that way but know when it’s time to separate stuff out, but you still need experience writing loosely coupled code to know at what point it becomes beneficial.

Enterprise Fizzbuzz is a intentionally humorous example of how it’s possible to go overboard with overengineering, and not every project is going to need to same level of decoupling.

MVC is generally considered a good starting point because most projects will become big enough for it to be helpful. When the project gets bigger, that level of decoupling isn’t enough and the M part needs to be split into several layers itself, and so forth. There isn’t a one-size fit all, but MVC is a good amount of decoupling for most projects.