Jens Krämer: Experience with JRuby on Rails

These are my live notes from Jens Krämer's talk on JRuby on Rails at Rails-Konferenz 2008.

• Not talking about ferret and full text search for a change :-)
• Germany's 1st JRuby on Rails project, started in Dec 2007
• JRuby 1.8.6 compatible – no problems w/ incompatibilities in his project
• Recommendation: Cherry as a wrapper for Swing if one is serious about GUI development
• Differences in JRuby: native threads, GC, Unicode, JIT
• JRuby benefits: runs everywhere, politics, performance
• It is possible to deploy a Rails app as a .war, even in practice
• Performance of Rails on Ruby and JRuby almost identical based on his experience
• Development done with JRuby and Webrick
• Test and production on JBoss
• JNDI Datasources as a benefit for admin/deployment
• Mongrel/Java considered exotic – why do JRuby when not deploying to a Java web server?
• JRuby-Rack bridges between servlet engine and Ruby and can run both Merb and Rails apps
• Project context: Medienservice Sachsen
• Media/PR handling for the German state of Saxonia
• External performance and load testing
• Live since April 08
• Features
• Historical correctness
• Scheduled publication
• Emailing to journalists (PDF, plain text, html, xml)
• Personalisation
• Asynchronous background process to handle mail delivery (including early releases of time-embargoed news)
• Main problem: migration
• Old application: WebObjects/Java
• 4 WO applications, Oracle backend w/ lots of views and stored procedures
• Goal: centralization to eGovernment Platform, based on JBoss and Apache, Oracle RAC
• DB Schema had to be kept, including Latin-1 data
• Functional equivalence
• Having tests performed by external company was an excellent experience
• Initial phase: Grails considered. Didn't work out; reasons: Grails is very different from Rails, relies on Hibernate, had many bugs (Autumn 2007)
• Using Hibernate meant having to write lots of XML config to match the existing database schema – learning curve way too high (no previous Hibernate experience)
• Didn't like GSP (Groovy Server Pages)
• Might have changed now
• Decision to use Rails
• Three separate applications: frontend, backend, mail handling
• ActiveRecord was easily flexible enough to handle the existing schema – configuration possible
• Specific models for existing views
• Models for more than one table/view (in case of filters)
• Many plugins
• Scheduling: handled via Cron in original version; BackgrounDrb was not an option
• Usage of Quartz scheduler (Rails plugin at https://projects.jkraemer.net/svdn/plugins/jruby/quartz_rails) [very cool!]
• Logging: log file handling didn't work because of concurrent access from multiple threads
• Log4J integration for Rails: https://projects.jkraemer.net/svdn/plugins/jruby/log4j_logger
• ServletContextListener changes default logger
• Oracle-specific stuff: transparent app failover only works with OCI
• Blob handling via JDBC streaming (manual JRuby coding)
• Nice pattern: high-level Ruby to script low-level Java libs
• Java Advanced Imaging API for thumbnails
• Apache FOP for XSLT
• Java-based clustered caching was considered, but not used: filesystem-based fragment caching
• to_java_bytes and from_java_bytes as conversion for usage of e.g. ByteArrayInputStreams
• mod_jk problems (not related to Rails)
• Requirements: 60 parallel users (with real, not artificially high load), no page returned in more than 3s
• 50-60 requests per second in a VM on a quad core box
• Summary
  • no problems with inaccessible target production environment - benefit of mature Java platform
  • local development w/ Webrick and local JBoss
  • JRuby and Rails absolutely production-ready
  • Customer was "tricked" into JRuby, but is happy - now asking for ways to more, even without JBoss :-)
  • Tests take too long because of JRuby startup time
  • No attempt to do development/test with CRuby/MRI because of Java dependencies

Q&A:

• Effort: 4 months, mostly one person (him).
• Reason for whole project: eGovernment initiative/centralization on JBoss/Apache
• Is JRuby an option for people w/o Java background: absolutely yes, although some choices might end up differently

Great talk!

On June 10, 2008 12:23 PM, John said:

links :

http://projects.jkraemer.net/svn/plugins/jruby/log4j_logger

http://projects.jkraemer.net/svn/plugins/jruby/quartz_rails

cheers.

On June 10, 2008 3:12 PM, Lars Fischer said:

So what is the point of Grails when us still need to learn Hibernate?

On June 10, 2008 10:33 PM, Arun Gupta said:

You can also consider using GlassFish for deploying Rails applications - natively or WAR-based. See more details at:

http://blogs.sun.com/arungupta/tags/rubyonrails

On June 10, 2008 10:37 PM, Stefan Tilkov said:

@Lars: This was interesting to me, too – I often heard the claim that having Hibernate at your disposal is great if you have a legacy DB scheme. In Jens’s experience, using ActiveRecord was even easier (although he quickly pointed out he was new to Hibernate).

On June 10, 2008 11:00 PM, Stefan Tilkov said:

@Arun: Good point. In addition to Glassfish and JBoss, we’ve also deployed JRuby apps to Tomcat and Jetty without any problems.

On June 12, 2008 11:10 AM, Leif said:

So, what is this Cherry that is being mentioned as a Swing wrapper? I can’t find anything on it.

On June 12, 2008 11:20 AM, Stefan Tilkov said:

I took notes while he was presenting, that’s why I misspelled it: It’s actually “Cheri”, more at http://cheri.rubyforge.org/

On June 16, 2008 2:22 PM, Leif said:

Thanks! :)

On January 15, 2009 8:09 AM, manmay said:

hello, I am trying to create a Jruby on rails app. with hibernate as back-end and rails as front-end. But i m not able to have hibernate configured for my app . can u please tell me how did u implement hibernate into u’r app. where to have jars,servlet.xml, web.xml, pojos, controllers , models, etc .. i m not able to understand the dir structure of the app….. help me out ..

thanks, manmay [email protected] [email protected]