The ongoing requirement
The client uses an external inventory management system to manage their inventory, which supports the Magento store as well as other brick and mortar stores selling items from the same warehouse. The system updates product quantities in the Magento catalog and Magento updates the inventory management system when sales are made. The ongoing requirement is to enhance and upgrade the interface as determined by changes made elsewhere.
The ongoing solution
When sales are made, XML is generated through an XSLT template from order parameters using the Xtento Order Export extension and handed off to custom classes. These classes exchange data with the inventory system using SOAP. I made significant enhancements to this interface to incorporate changes to sales tax, fulfillment of sales by drop shippers, rather than through the warehouse, and the taking of charitable donations as part of the order. I also laid the groundwork for a SOAP API upgrade.