Splitting jruby-complete.jar up for Google App Engine

When we write a web application using JRuby, we need jruby-complete.jar included in a war to use builtin libraries. The builtin libraries are supposed to be located under jruby.home, so the jruby.home system property is expected to be set correctly. However, we need an alternative to set the property since setting jruby.home on the web application doesn't make sense. The answer is jruby-complete.jar, which has builtin libraries under META-INF/jruby.home directory in it.

When we use Google App Engine, another problem pops up. GAE has 10MB limit per each file to upload (http://googleappengine.blogspot.com/2009/02/skys-almost-limit-high-cpu-is-no-more.html). The size of jruby-complete.jar is unfortunately over 10MB. The shell script to split jruby-complete.jar up into two jar archives has been introduced at http://olabini.com/blog/2009/04/jruby-on-rails-on-google-app-engine/. However, I learned the way in the blog was already obsolete when I filed JRUBY-3949. The smart way of doing that was already out there. The latest JRuby, I mean, JRuby 1.4.0dev in git HEAD has had a Rakefile to create jars.

This is what I acutually did on a terminal:

$ git clone git://kenai.com/jruby~main
$ cd jruby~main
$ export JRUBY_HOME=`pwd`
$ PATH=$JRUBY_HOME/bin:$PATH
$ ant
$ gem install rake
$ gem install hoe
$ cd gem
$ rake update

Then, jruby-core-1.4.0dev.jar and jruby-stdlib-1.4.0dev.jar was built in jruby~main/gem/lib directory.

Finally yaml worked on Google App Engine

In my previous post, I wrote about my struggle over an application on Google App Engine that uses JRuby's builtin library, yaml. I found the reason of the error at JRUBY-3892. Builtin library needs jruby.home environment variable to be set correctly, and it should be done in jruby-complete.jar. But, jruby-complete.jar built from old JRuby 1.4.0dev had a somewhat broken path. Since the issue has been resolved in the end of Auguest, I tried again using the latest JRuby 1.4.0dev cloned out from git repo. It worked. So, the final release of JRuby 1.4.0 won't have this problem.

Now, my sample Servlet, ParsenRunServlet is working at http://servletgarden-in-red.appspot.com/. If you are interested in the code, those are in JRuby Embed API Wiki.