architecture - Top-down or bottom-up design? -

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there 2 approaches designing system. advantages , disadvantages? when should use which? should combine approaches? how?

roughly speaking, top-down comes decomposition of problem space sub-problems, while bottom-up comes organizing parts of solution space larger chunks.

to able use top-down, need solid understanding of problem, i.e. have solid requirements in hand. bottom-up effective, need solving 'standard' problem pieces well-known, exact assembly might need experimentation before right.

you should read parnas' brilliant paper a rational design process , how fake it more on issue. answer is: use both, appropriate. when you're done, make (in specifications, design documentation , user documentation) if had done top-down.


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