RoR App to run under JRuby

After deciding on the platform, one of the big things to get accomplished was getting the current application to run inside a JRuby container inside Glassfish.

This was a bit challenging at first, and it still isn't all quite there, but the main core of the app is now running in there, with a few changes.

We are not deploying via a war file (yet) - since we are just building this, but deploying as a directory (for development) from my git workspace to build up the configuration steps.

There were quite a few challenges (and more to come) - some of which were based on the gem compatibilities between ruby and jruby - more notably libxml and libxslt - which rely on native libraries.

Before I got here, this was tackled a little bit by another engineer here, Rich, who created an xml_lib.rb that wrapped what we needed via the libxml and libxslt libraries to utilize their java counterparts - so that was a big boost for this process.

We will probably replace those with more robust ones if we need in the future, but this library works great for what we are using it for at the moment. There is a port of libxml-ruby called libxml-jruby, written by Dylan Vaughn, which will do what we need - and we will probably pull out the XSLT functions that Rich wrote and separate the lib this way.

A big part of this was getting the correct gems installed and being used for jruby, and adjustments in the configurations for the current app to separate what to load if running under jruby as opposed to ruby.

Example - in 'conf/environment.rb' - the config gems were separated out:

if RUBY_PLATFORM =~ /java/
config.gem 'jdbc-postgres', :lib => 'jdbc/postgres'
config.gem 'activerecord-jdbc-adapter', :lib => 'jdbc_adapter'
config.gem 'activerecord-jdbcpostgresql-adapter',
      :lib => 'active_record/connection_adapters/jdbcpostgresql_adapter'
else
config.gem 'pg', :version => '0.8.0'
config.gem 'libxml-ruby', :lib => 'xml/libxml', :version => '1.1.3'
config.gem 'libxslt-ruby', :lib => 'libxslt', :version => '0.9.2'
end

After installing and setting up Glassfish with a new domain and installing jruby, needed to make the jruby container available to Glassfish:

% asadmin create-domain --adminport 4848 extension
...
...
Command create-domain executed successfully.

% asadmin configure-jruby-container --jruby-home=/usr/local/jruby

and then deployed my current app (being in the parent dir of the rails app directory)

% asadmin deploy --property jruby.rackEnv=development core/

Starting my domain here, I was able to access the app successfully via the context of the app name (http://localhost:8080/core/). Adding 'context-root="/"' to the <application ... section allowed me to access without adding '/core/' to my URL.

Notice the setting of:

--property jruby.rackEnv=development

This is basically the equivalent of setting RAILS_ENV=development in your environment.

Next step was getting the db to work with jdbc/jndi pooling.

*Note: One issue I was having was the complaining of missing the class javax.jms.MessageListener:

/usr/local/jruby/lib/ruby/site_ruby/shared/builtin/javasupport/core_ext/object.rb:37:
in `get_proxy_or_package_under_package':
NameError: cannot load Java class javax.jms.MessageListener

Following the directions on http://wiki.glassfish.java.net/Wiki.jsp?page=OpenMQJRuby, I created and moved the appropriate jms/imq jar files to my domain/lib/ext directory and these are no longer an issue. I will have to see why this was when I work with the MQ issues (and converting from ActiveMQ to OpenMQ).

1. .../mq/lib/jms.jar
2. .../mq/lib/imq.jar
3. .../mq/lib/imqjmsra.jar

imqjmsra.jar is created by extracting it from imqjmsra.rar:

jar xvf imqjmsra.rar imqjmsra.jar

Move these into the domain/lib/ext directory. These will also need to be included in your classpath when using the jruby console.