Spring Boot. What I learned is: I had no idea how much I hate "configuration". Spring is a Java dependency injection system that uses XML-based configuration.

Spring Boot. What I learned is: I had no idea how much I hate "configuration". Spring is a Java dependency injection system that uses XML-based configuration. Recognising that XML sucked, they later added 2 additional ways to specify configuration, which they call annotation-based configuration and Java-based configuration. Both kinds use annotations. Both kinds use Java. Spring Boot is a layer on top of regular Spring that tries to make things simpler by automatically guessing what you're trying to do and configuring it for you, with something it calls auto-configuration. Just trying to understand what makes what happen in a (very simple) Spring Boot app sucked weeks from my life.