Why do a lot of projects only offer source and no jars for download?

Question

I've seen a lot of projects, even from big companies like Elephant Bird (Twitter) and Akela (Mozilla) that offer source and ask you to compile it yourself instead of also offering jars. Is there some benefit to compiling in your own environment instead of just downloading a jar someone else has compiled?

Answer 1

1. Dependencies are not in the same location or even have the same version on every machine. It is simpler to detect where they are at compile-time.

2. If there is any native code (sometimes just for optimization) in a project, there are probably platform-dependent flags that need to be set at compile-time.