title: What`s the best practice for Magento to update stock from code
body: <p>I have to integrate my webshop with an external system. This system provides several functionalities, described in their API. This is what I want to do:</p>
  
  <ul>
  <li>Import/sync products (this is available as CSV via request)</li>
  <li>Update stock of products (also available as webrequest)</li>
  </ul>
  
  <p>So I have to hook into the Magento stock check and I want some script which updates the products like everyday.</p>
  
  <p>Where should I implement my changes? What is the best way to do this? I can imagine Magento already have some API stock functionalities, but can`t seem to find the right documentation.</p>
  
  <p>Thanks in advance!</p>