Sunday: JRuby on Rails

By Charles Oliver Nutter and Thomas Enebo

jruby

• ruby 1.8ish
• a non-java language for the jvm
• helping to expand ruby’s reach
• helping the world better understand ruby

jruby is not

• an attempt to polute or fork ruby
• an admission that java sucks
• the answer to every ruby problem
• an attempt to alter ruby or add incompatible features
• slow
• obvious libs and gems preinstalled
  • rubygems
  • rake
  • rspec
• mongrel supports jruby
• rails just works
  • major orgs now investing in jruby on rails

justification

or dear god why would you do such a thing

• supporting the status quo
  • jruby supports ruby 1.8’s string
  • jruby works with active support multibyte
• exposing java unicode
  • java strings are all unicode and all libs are unicode friendly
• ruby 2.0 string support on the way
• jruby supports ruby’s thread api
  • even the ones we hate: kiill, raise
• most jvms are native threaded

what’s the most cited pain point for rails?

the basics

• most gems just work
  • rails
  • redcloth, bluecloth
  • hpricot
  • basically anything that is pure ruby
• jruby script/generate controller test hello

a few things are different

1: database support

• default pure ruby mysql and postgres work
• has jdbc support which is different and fast but just as easy (jdbc:mysql in database.yml)
• jndi for connection pooling
• active record-jdbc doesn’t support all
  • jdbc has no schema management api
  • different databases quote differently
  • some databases are missing features
• focused on databases close to rails
  • mysql, 100%
  • others at varying levels but coming along

2: no native extensions

• some ports are done that work
  • mongrel and hpricot are done, rmagick in progress

3: command line performance

demo

• jruby plugin called goldspike for creating wars
  • jruby -S rake war:standalone:create
• there is a glassfish gem for deployment to run everything on the command line (much like mongrel, bug is that it doesn’t serve static files yet)

migration

• it can be done, it’s basically ruby

database

• mysql the best, oracle is being improved by community, not in CI
• working well because they’re part of rails tests
• tricky on some db’s that don’t have all features
• fixtures working well

native extension issue

• use something else
• use an equivalent java library
• port the library yourself
• port by wrapping a java library
  • their favorite method, as it is the least work

deployment issue

• mongrel
• war file
  • multi-app, multi request concurrency
  • resource pooling
  • “good” java EE features
  • bound to monitoring of app server itself for tailing log files
• grizzly/glasssfish v3 option
  • lightweight, gem installabe like mongrel
  • concurrency, etc.

beyond rails

• calling java libraries from rail
  • this is really cool, you can code java and it looks just like ruby, auto getters and setters, so cool