I installed on my local system the CouchDB database, without any problem. Then I tried the given Ruby code to access the DB. It's really easy as CouchDB has no query language, but it uses http messages as directives; so, as I supposed, the Ruby code worked flawlessly.
THEN, I tried the Java code. I'm still trying it.Unluckily, as you can see on this page,
the documentation is lacking. I'll work on this during the next days to make it better.