What sources would you recommend for organizing applications?

Question

Database design

There was a small site with ads, over time it got hung up, chat on sockets, paid functionality in the form of paid ads with different payment systems, besides, the project seems to be the same, but it is used on different geos (now 3 countries, it is planned about 10), it has a bunch of its own local parameters defined for a specific country, there is an api for mobile applications.
And then we faced the fact that there is not enough skill for the further correct and modern development of the project. Remaking one part, very quickly, we come to the conclusion that it needs to be remade again.
It seems to me that there is already a need to break this project into a service architecture, but there is not enough experience for implementation and planning.
what books to read? what courses to attend? where to get such info?
more specifically on: -
designing applications
- implementing a service architecture
- designing a database, well, and everything else that may be related to what I described.
Thanks in advance)

Answer 1

Here.

Answer 2

You need an architect on the team who will plan the new architecture and prepare a plan for its migration. Preferably very experienced. Without knowing how to architecture on your own, you will only aggravate the situation with all sorts of "I read here" and "and here they do this"

Answer 3

1. Draw what is.
   
2. Look to gestalt
   
3. draw what will be
   
4. Make a transition plan
   
5. Go
   

Answer 4

The most accessible book on the topic of application architecture design, in my opinion, is from Robert Martin "Principles, patterns and methods of agile development on .... There is also his book " Agile development of programs in Java and C ++ "