I'm working my way through JPA in Action.

I have a question about the difference between value types and components. The book says things like a value type depends entirely on an entity for its lifecycle, and that no other entity holds a reference ( a field reference i assume ) to the value type candidate.

With this understanding, I have decided that, in my own domain model, that an event in a calendar, is a value type. I have a user defined class for CalendarEvent and it depends entirely upon its association with a given Calendar.

But is it a component. The book's language makes components sound just like value types. Describing a component as something participating in "composition". By my understanding of composition, the CalendarEvents have this relationship to a Calendar. Like wheels to a car, for instance.

However, components are mapped in hibernate to columns in the "owning" entities table. This will clearly not work for events in a calendar, due to the fact that there can be many of them.

I'm looking for some semantic illumination. Please advise.

You've got it all correct, but you have to notice the line between components that are part of the owning entity and collections of components. The latter looks (relationally) like any other FK relationship. It is Hibernate that defines the lifecycle and imposes query constraints that cause them to behave like the former. Does that make sense?