# Learn 101

* 100: KEEPE IT SIMPLEME How works a hierarchical data lookup? 
  - Query a key
  - Kheops is composed of 2 parts:
    + It will first look in different locations the key. It is usually files, but it can also be an url or anything.
  - Lookup data in a tree of files
    + Goes sequentially according the backends list
      * Backend/Engine list is modular
      * Engine Plugin: Jerakia/HIera/Ansible/Curl
      * Backend Plugin: loop/hier
    + All result are returned, and then the rules are applied
    + Rules match to a key and apply a strategy (essentially determine if and how the different value are merged or replaced). It can also apply filter to the result and modify its content (future).
      * This is modular
      * Strategy: last/schema
        - Last will always take the last found value, whatever what it previously found. 
        - schema: It will take into account the strucutre of the data and try to merge them intelligentelly. 
    + Then it returns the result