Questions on Spring Internals

An internal mechanism of a framework is work the framework does on your behalf that no line of your own code shows. Spring has four that matter day to day: a container that builds objects, proxies that wrap them, conditions that decide which beans exist, and an ordered list of setting sources.

Almost every surprise in the booking service came from one of these four. A transaction that never started, a check that ran too late, a bean nobody declared: each had a mechanism behind it. Each mechanism was built or measured in an earlier lesson.