When you’re working on a monolithic system and automate tests for it — which you’re supposed to — the time it takes to run the whole suite grows proportionally with the size of the system. In a significantly large system, the whole run might take many hours or a few days to complete.
You don’t start building a house without an architecture, yet when it comes to software development, most projects don’t have any well-defined architecture.
Many people attribute the difference in approaches to the fact that it’s hard to change the house that’s half done while software is malleable and hence can be changed easily at any moment.
But that’s not true. The further down the road a software project is, the harder and more expensive it is to change its architecture. It’s still doable, but it unnecessarily costs much more than it would’ve cost if some time would’ve been spent on the initial architecture.
From time to time, I meet people that claim they do microservices. Since I’m interested to hear more real world experiences, I dig deeper by asking technical questions. And pretty often I learn that even though they have multiple microservices, they all use the same database.
In a monolithic system, it’s too easy to integrate with code from another part of the system. It simplifies initial development but leads to a big ball of mud that’s very hard to maintain.
When you have a monolithic system of any significant size, it’s likely different parts of it require different types of resources to function optimally. Some parts are CPU intensive, while other parts are RAM intensive. It’s possible that there’s at least one part that would greatly benefit from using GPUs for some intensive computational processing.
There are valid reasons most developers don’t like working with old or outdated technology.
Waterfall has clearly defined stages of software development: requirements → architecture → design → implementation → and so on. (As a side note, some people don’t differentiate between architecture and design, but I consider them separate. Architecture is strategic, while design is tactical.)
Then along came Agile. Most people started considering Waterfall evil and started opposing everything about it. They threw away the baby with the bathwater. And by that I mean essential practices like architecting got thrown away along with Waterfall.