we are a logistic company with a warehouse. A new customer of us has a Shopify shop and we should handle the products in our warehouse and do the shipping.
What would be the best way to connect our (Ruby on Rails) logistic software to Shopify e.g. to receive orders and push stock changes?
I need some hints how to start and how the technical and business workflows will be and if I need to develop an official Shopify app or can I simply use the Shopify REST API?
Many thanks in advance for the answers.
I found the reference app https://github.com/Shopify/shopify_app and tried to get it working by it's README. I run the Rails generators and use the generated default models. I created a partner account, a development shop and a VPN tunnel to my local webservice with ngrok. But I stuck at the point when I try to install my app to the development shop. OAuth raises always an invalid_site error, like in https://github.com/Shopify/shopify_app/issues/860.
Does anyone have an idea how to solve this problem?