When modernizing applications, we help organizations select a software architecture that’s flexible, yet can last many years. A recent article about our client K3S got our attention. Author Alex Woodie wrote that the inventory forecasting software vendor had updated their package with an attractive web-based interface using PHP, while adapting their existing RPG code into APIs written in RPG. But I knew there was more to this story. So I asked King Harrison IV—K3S’s executive vice president, friend, and founding member of Club Seiden— to elaborate on their choice of RPG APIs.