If the gateway is unavailable(or DDOS prevention)So you have in the code an error occurs that you cannot intercept.
the order is not issued, the buyer sees a page 500 that is bad
no emulation of multithreading and the creation of demons?
In General you need a quick working version with no claims to the correctness of the architecture and other practices
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5 years project by the way, I do not think that earned less money than some of your properly designed solution. - Delphine4 commented on July 9th 19 at 10:40