Interview: JOLIE and Service-Oriented Computing Explained (KDE.News)

There's no short explanation to this, but the gist of it is that the difference between a language and a
library in this case is that the language is more straightforward to use. It's designed to express quite
clearly the sort of things you need to in setting up ad hoc SOA systems; you could certainly do it with
a library API only but it'd be even more cumbersome to use. The language itself is pretty basic and
focused (not meant to replace any other language, for instance). Think of it as the replacement for
XML based descriptions used by some other SOA frameworks. It's just a design choice, and one that
seems sensible so far. Maybe one day someone will wrap it all in a higher level API, who knows. ;)