BuyIT’s marketing department implements a system for managing the vendors it works with and their contracts. There is nothing special or complex about the system—it’s just some CRUD user interfaces for entering data. In other words, it is a typical supporting subdomain.

However, a few years after BuyIT began implementing the in-house solution, an open source contracts management solution came out. The open source project imple‐ ments the same functionality as the existing solution and has more advanced features, like OCR and full-text search. These additional features had been on BuyIT’s backlog for a long time but were never prioritized because of their low business impact. Hence, the company decides to ditch the in-house solution in favor of integrating the open source solution. In doing so, the document management subdomain turns from a supporting into a generic subdomain.