Introducing JRuby-Rack

Nick Sieger — Thu, 08 May 2008 17:31:00 +0000

Continuing in the spirit of Conference-Driven Development, I’m happy to announce the first public release of JRuby-Rack! You can use it to run Rails, Merb, or any Rack-compatible application inside a Java application server.

Also released today is Warbler 0.9.9, which has been updated to bundle JRuby-Rack.

In addition to providing as seamless a connection as possible between the servlet environment and Rack, JRuby-Rack (along with Warbler) is also bridging the gap between Ruby and Java web development. Some of the things it does are:

Makes the Java servlet context and servlet request available to Ruby through special variables in the Rack environment
Servlet request attributes from Java are passed through and available in the Rack environment. Request attributes can override Rack variables such as PATH_INFO, QUERY_STRING etc.
Configures Rails deployment options such as page caching directories and session handling automatically and optimally for the servlet environment.

I’ve also included the beginnings of some extensions that should help integrate Rails with existing Java web frameworks, servlets, JSPs, and other code. For example, you can invoke a Rails request from within a JSP with a tag:

<jruby-rack:rails path="/projects/activity" params="layout=none"/>

You can set servlet and session attributes and forward to other servlets and JSPs from your Rails controllers:

class DemoController < ApplicationController
  def index
    servlet_request["hello"] = "world!"
    session["rails"] = "Visible to java!"
    forward_to "/attributes.jsp"
  end
end

and read them from within the servlet or JSP:

<dl>
  <dt><tt>servlet_request["hello"] | request.getAttribute("hello")</tt></dt>
  <dd><%= request.getAttribute("hello") %></dd>
  <dt><tt>session["rails"] | session.getAttribute("rails")</tt></dt>
  <dd><%= session.getAttribute("rails") %></dd>
</dl>

This is just the beginning of this kind of integration, and I’m interested where people take it. I think this provides a nifty way to start integrating Rails bits into existing applications or reuse existing Java web application code.

I’ve tagged the release with an 0.9 version number. I believe the bits are ready for serious use, but could use some help pounding out a few more bugs before calling it 1.0. So jruby -S gem install warbler today, try it out, and bring plenty of feedback to the JRuby user list!

Blog Setup

Nick Sieger — Thu, 10 Jul 2008 05:10:27 +0000

The other day several people chimed in wondering how I set up this blog with JRuby and Glassfish. One of the reasons I didn’t include the details in the post is that it’s not really much different than any JRuby/Glassfish/Warbler deployment, but in case you don’t know what that looks like, here are the basics.

Preconditions (Java)

I’m running on a Joyent Accelerator, which runs OpenSolaris, which has JDK 6 installed by default. If you’re running on some flavor of Linux, hopefully there’s a package available for you to install, otherwise you may have to download a self-extracting binary.

Install Glassfish

This step is actually straightforward; not at all as problematic as you might expect of a piece of Java technology! In the parent directory where you want Glassfish to be installed (substituting the name of the Glassfish jar you downloaded as appropriate):

java -Xmx256m -jar glassfish-installer-v2ur2-b04-sunos_x86.jar
cd glassfish
chmod -R +x lib/ant/bin
./lib/ant/bin/ant -f setup.xml

Start Glassfish.

./bin/asadmin start-domain

You may want to add GLASSFISH/bin to your path so that you can run the Glassfish asadmin command from anywhere.

On Solaris, SMF is the subsystem that is used to ensure services are started at boot time (among other things). Glassfish works nicely with SMF. On other systems, there may be /etc/rc.d init scripts out there, or you can roll your own (asadmin start-domain and asadmin stop-domain).

Install JRuby

Download JRuby and unpack it somewhere. I recommend adding JRUBY_HOME/bin to the end of your path, so it doesn’t clash with Matz-Ruby.

Install Warbler and activerecord-jdbcmysql-adapter

In addition to Warbler, I’m using the activerecord-jdbcmysql-adapter to connect to the blog’s database. Both can be installed with Rubygems:

jruby -S gem install warbler activerecord-jdbcmysql-adapter

With Rails 2 and up, the application’s config/database.yml file should be updated for adapter: jdbcmysql:

<% jdbc = defined?(JRUBY_VERSION) ? 'jdbc' : '' %>
development:
  adapter: <%= jdbc %>mysql
  encoding: utf8
  database: testapp_development
  username: root
  password:
  socket: /tmp/mysql.sock
# same for test/production...

Otherwise, you need to jump through some extra environment.rb configuration hoops.

Configure Warbler

Warbler needs to be told about any gems that your application uses. To generate a Warbler configuration file:

jruby -S warble config

The file is generated at config/warble.rb. In it, modify the following sections:

config.gems = ["activerecord-jdbcmysql-adapter"]
...
config.webxml.jruby.min.runtimes = 2
config.webxml.jruby.max.runtimes = 4

Build and deploy the .war

jruby -S warble
asadmin deploy --contextroot / blog.war

(--contextroot / makes the application rooted at / in the server, rather than at /blog which would be the default.)

At this point, the blog application is up and running on port 8080. I had previously been running the blog with an Apache/.htaccess-based setup reverse-proxying to mongrel, so all I had to do was change the port. I haven’t touched it since.

But is this right for you?

Chances are, this setup is overkill for a simple blog. If you’re going to try it, I’d recommend at minimum running on a VPS with at least 1G of memory. But once you get the core pieces in place, updating and re-deploying the application is really just as simple as the last two commands. It’s mundane and boring in its simplicity. But boring is good when you don’t want to worry about having to keep Mongrel running, or max out the memory in your server and make it unstable.

Nick Sieger: Tag rack