The framework components attempt to follow the principle of pragmatic (KISS) design. Practically, it means that each the component must follow given rules:
The framework relies on the application server to run some of its services. PHP codebase mostly centered around quick delivery of efficient business logic. The application server, Golang based, is focused on efficiently solving the infrastructure tasks.
Spiral application server is a customized version of RoadRunner.
Read about application lifecycle here.