HttpKernel
2 exercises work on this concept, by writing code in the browser.
In Practice
- One import at a time, with #[Lock] #[Lock] puts a lock on a controller: a concurrent request gets a 409, and reads can share a lock between them.
- Reading a header with #[MapRequestHeader] An HTTP header arrives directly as a controller argument, and a missing header gives a 400 without a line of code.