JRuby via jsr223

jsr223 allows embedding jruby code in java.

Unfortunately, at least on Debian lenny, setup requires some work.

First of all, be sure to install java1.6, for example with sun-java6-jdk package.

Then two more downloads are required:
* jruby, for instance jruby1.1.6
* jruby-engine-1.1.6.zip
Version of jruby engine must match jruby version.

Unpack Jruby, define $JRUBY_HOME to the expanded directory and have PATH=$PATH:$JRUBY_HOME/bin.

Unpack jruby-engine-*.zip.

Include in classpath jruby.jar and jruby-engine.jar from the /lib dir of the unpacked tarball.

Compile javacode as usual with javac; to run code, it could be necessary to add a -cp .:./jruby.jar:./jruby-engine.jar switch to java.

It should be possible to use jsr223-engines tarball instead of jruby-engine-*, but I tried with no luck. jruby1.0 is a deb package, but installing it didn't help, and I feared it could introduce path problems so I removed it.