The server's role.
WHAT IT HANDLES
Receiving and responding to requests Business logic and rules Data storage and retrieval Authentication and authorisation Integration with other systems Background and scheduled work
WHAT IT IS RESPONSIBLE FOR THAT THE CLIENT IS NOT
Anything requiring trust.
WHY
Everything running in a browser or a mobile application is under the user's control and can be altered.
WHAT THAT MEANS SPECIFICALLY
Prices are calculated on the server Permissions are checked on the server Validation on the server is the real validation Secrets exist only on the server
WHAT THE CLIENT MAY DO
Present, interact, and validate for convenience.
WHAT EVERY BACKEND NEEDS REGARDLESS OF LANGUAGE
Input validation Consistent error handling Structured logging Configuration outside the code A repeatable deployment, with a way to revert
WHAT DIFFERS BETWEEN STACKS
Syntax, libraries, conventions and tooling.
WHAT DOES NOT
Those requirements, and the reasoning behind them.
WHAT TO LEARN
The principles, which transfer.