Recently I have needed to integrate a Quickbooks Desktop instance with my Rails app. 

As of Summer 2013 Intuit has deprecated the REST API whereby a client can communicate with a Quickbooks Desktop instance via REST. This leaves either the QWC route or straight-up Windows COM programming. I’d rather hit my thumbs with a 10 lb. sledge than use COM. So QWC it is!

The QWC approach uses SOAP - which stands for Slippery Obtuse Alligator Playtime. Which is a perfectly apt description of the byzantine SOAP protocol.

Fortunately the WashOut gem does most of the heavy lifting. The hardest part was properly configuring the WashOut endpoint. Check out this Gist which contains the pertinent parts:

In my case I have Quickbooks Pro 2013 running in a VMWare instance on a OS X host. My Rails app is running on the OS X host. Thus we need to have a publicly accessible URL for the AppUrl in the QWC config. Which is really my Rails apps in development exposed to the World Wide Web. 

I have found the ngrok service to be fantastic for this. I run my Rails app locally on port 3000, then run `ngrok 3000`. I am given an https URL which I can then use in the `.qwc` file.