Ordering process consists of the several steps

  - Pre-order validation - Validation checks if the order has and performs initial validation of customer's data entered in the form
  - case of validation passed, regardless of the payment type the order is registered along with the order details. For Paypal it does include only order details with empty customer info.
  - After order registration in database - 
      - For Invoice just mark order as successful, compose and sends notification to customer/webmaster
      - For Paypal the script awaits data block from paypal about order completion, then mark order as successful, compose and sends notification to customer/webmaster
      - For Credit Card payment the script awaits data block from credit card about order completion, then mark order as successful, compose and sends notification to customer/webmaster