separation of mechanism and policy

mechanism determines how to do something;

policies determin what will be done.

 

policies

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machanism

 

example:

the use of card keys to gain access to lock the door.

machanism: reader, locker, server

policy: which people allowed, which time..

 

contrast this with issuing physical keys: if you want to change who can open a door, you have to issue new keys and change the lock.