Shipping applications provide customers with online rates after they fill in their address details.
While the shipping methods page loads for the customer, the following flow happens in the background:
First, Ecwid gets order details and sends them a POST request to the app's shippingUrl with the data formatted as an unencrypted JSON.
Ecwid won't call shippingUrl if it has already been called in less than 5 minutes or the order details haven't changed.
After that, the app must parse the data and return shipping rates within the 10-second window. Upon receiving the response, Ecwid loads the next checkout page and displays shipping options to the customer.
