Many companies who have invested a lot of time and money in Java technology could still benefit greatly from Ruby on Rails by using it to build new sites that make use of their backend Java based services.

Here’s an example of an RSpec test that uses a Java DAO, provided by Spring to access a database with JPA / Hibernate.

it "should retrieve an Account by ID" do
  load_data "dao/accounts.xml"
  dao = spring.getBean 'accountDao'
  acct = dao.find "5000"
  acct.should_not be_nil
  acct.getName.should == "Alpha"
end

It’s surprisingly easy to use a Spring context here by adding the following method to my spec_helper:

import 'org.springframework.context.support.ClassPathXmlApplicationContext'
import 'org.springframework.core.io.ClassPathResource'
 
def spring(context_file="beans.xml")
  java.lang.Thread.current_thread.context_class_loader =
      JRuby.runtime.getJRubyClassLoader
  @ctx ||= ClassPathXmlApplicationContext.new context_file
end

Using that helper I am able to access any component managed by Spring. As designed, Spring will wire up any required dependencies, provide a pooled database connection, and handle any other configuration necessary so that the bean returned is ready to use.

My test also uses DBUnit to load an XML fixture. It can do that by adding this method to spec_helper:

import 'org.dbunit.database.DatabaseConnection'
import 'org.dbunit.dataset.xml.FlatXmlDataSet'
import 'org.dbunit.operation.DatabaseOperation'
 
def load_data(data_file)
  begin
    @dataSource ||= spring.getBean 'dataSource'
    @conn ||= DatabaseConnection.new @dataSource.getConnection
    @dataset ||=
        FlatXmlDataSet.new(ClassPathResource.new(data_file).getInputStream)
    DatabaseOperation::CLEAN_INSERT.execute(@conn, @dataset)
  rescue
    print "load_data error: ", $!, "\n"
  end
end

DBUnit provides a useful way to load data fixtures into a test database. The reason I’m using DBUnit instead of the more common YAML format used in Rails apps, is so that I can make use of the fixtures already available in the Java project.

Here’s what my DBUnit fixture looks like:

This combination of technologies seems like a pretty powerful combination to me, especially for those companies who are entrenched in Java and are looking for a way to improve their productivity.

I’m interested to know who else is using this type of setup. Leave a comment and describe your experience.

def nested_error_messages_for(object)
  if ([Symbol, String].member? object.class)
    object = instance_variable_get("@#{object}")
  end
  unless object.nil? || object.errors.count.zero?
    error_messages = object.errors.to_a.uniq.map do |key, value|
      object2 = object.send(key)
      if object2.is_a?(Array)
        object2.collect {|obj| 
          content_tag(:li, nested_error_messages_for(obj)) 
        }
      elsif object2.is_a?(ActiveRecord::Base)
        content_tag(:li, nested_error_messages_for(object2))
      elsif value.match(/^\^/)
        content_tag(:li, value[1..value.length])
      else
        content_tag(:li, 
           "#{key.underscore.split('_').join(' ').humanize} #{value}")
      end
    end
    content_tag(:div,
      content_tag(:div, 
        "#{object.class} has errors", :class => 'error_field') +
      content_tag(:ul, error_messages), :class => 'error_block')
    else
      ''
    end
end

To use it, just replace your current call to error_messages_for with nested_error_messages_for. There’s nothing extra that needs to be done in the controller as with some recipes. You’ll also want to make it look good with some CSS.

I’m pretty sure there’s more that could be done with this, but thought I’d present it here first and try to get some feedback before turning it into a gem. Let me know how it works for you.

User.count(:conditions => ['created_at > ?', 30.days.ago])

Here’s a simple extension I made to ActiveRecord to DRY it up:

module ActiveRecord
  class Base
      def self.count_since(time_ago)
        count(:conditions => ['created_at > ?', time_ago])
      end
  end
end

Put that snippet in a file in your lib directory. I called mine rails_extensions.rb. Then add require ‘rails_extensions’ to the bottom of your environment.rb file.

Now you can just do:

User.count_since(30.days.ago)

That’s a little cleaner, don’t you think?

1. configure –prefix=/usr/local –enable-mods-shared=all –enable-ssl –enable-proxy
2. make
3. sudo make install

Doh! That’s probably not what you wanted. Now you have stuff like

• /usr/local/build
• /usr/local/icons

You’d have been better off going with Apache 2’s default prefix which is /usr/local/apache2. The problem is there’s no uninstall! If that’s happened to you and you just made the mistake a short time ago, try this:

1. Make sure you have enough free space for a backup of /usr/local

   $ sudo du -sh /usr/local
   2.2G /usr/local

   $ df -h

2. Back it up

   $ tar cvf /tmp/usr_local.tar /usr/local

3. Find out which files you just installed

   $ sudo find . -type f -newerct ‘60 minutes ago’ > /tmp/uninstall_files.txt

   $ sudo find . -type d -newerct ‘60 minutes ago’ > /tmp/uninstall_dirs.txt

4. Inspect the file you just created and remove things that don’t belong (e.g. mysql)
5. Remove the files (don’t get creative and add -r to rm — you did backup, right?)

   $ cat uninstall_files.txt | sudo xargs rm

   $ cat uninstall_dirs.txt | sudo xargs rmdir

Now, take off that prefix and try the 3-step again.

Autotest.add_hook :run do |autotest|
  autotest.add_exception(/^\.\/vendor/)
  autotest.add_exception(/\.svn/)
end

Thanks Ryan and David for the updates!

I’ve been noticing in my current project that running autotest was constantly consuming about 25-30% of my cpu and causing my macbook pro to run really hot. I did a little googling and found this discussion on the topic.

For me, my problem was definitely the vendor directory (~3500 files in 4 plugins: rspec, rspec_on_rails, restful_open_id_authentication and active_merchant). I tried excluding the entire directory by adding this to my ~/.autotest file:

Autotest.add_hook :initialize do |autotest|
  autotest.exceptions <<
   %r%^\./(?:db|doc|log|public|script|vendor|previous_failures.txt)%
end

However, that didn’t work. After some investigation, I found out that the rspec_on_rails plugin in my vendor directory was subclassing Autotest::Rspec and setting it’s own exceptions string like this:

def initialize
  super
  @exceptions = 
   %r%^\./(?:db|doc|log|public|script|vendor\/rails|previous_failures.txt)%
...

See the problem? It dutifully calls super so AutoTest:initialize can do it’s stuff (including calling my hook) and then wipes out the exception string with it’s own.

So, I browsed the lib/autotest.rb code and found another hook. Adding this to my ~/.autotest now lowers the cpu usage to about 5%. Huzzah!

Autotest.add_hook :run do |autotest|
  autotest.exceptions = Regexp.union(/^\.\/vendor/, autotest.exceptions)
end

The issue is that Facebook is going to start putting more of its own ads throughout the site. Big surprise. However, Facebook also allows apps to generally put whatever they want in the application canvas, including ads. If Facebook advertises something else outside the canvas then it’s not that big a deal to me. As a developer, I don’t really need them to provide me an “ad widget” as the author suggests; I can use Google Ads, The Deck or whatever.

If a small application developer is under the illusion that he can win a fight with a big-brand widget, that’s a bad plan, says Gerd Leonhard, chief executive of Sonific, which recently launched a music widget on Facebook.

Strange comment. “Sonific” doesn’t sound like a big brand to me, and yet they just launched a music widget? Good for them. However, it seems to me like they’re trying to scare off competition. Also, the net is the quintessential mechanism for some little guy knocking over “big brands”. In fact, that’s what Facebook is!

A couple months ago, we launched our first Facebook app for I’m In. Within a week about 1000 people had installed it to check it out. That’s pretty cool, considering all we had to do was get it added to the Facebook directory. So, over the long run will it generate more transactions for I’m In? I think so, but time will tell. For a site like that, it wouldn’t take too many added sales to cover the cost of building an app like Mad Libs™.

All that’s necessary to integrate any of your existing models with Amazon is to add a require line to the top of your model file and then an acts_as_amazon_product line just inside your class definition.

require 'acts_as_amazon_product'
 
class Book < ActiveRecord::Base
  acts_as_amazon_product(
      :asin => 'isbn', :name => 'title', 
      :access_key => '0123456', 
      :associate_tag => 'assoc-20')
end

After this, you can access Amazon data in your controllers or views like this:

@book = Book.new(:title => 'Getting Things Done')
@book.amazon.isbn
@book.amazon.title
@book.amazon.author
@book.amazon.small_image_url
 
@book.amazon.get('itemattributes/foobar')

The code does not require changing any current database tables. It only requires adding one migration for a single new table used to cache responses from Amazon:

ActiveRecord::Base.connection.create_table :amazon_products do |t|
  t.column :asin, :string
  t.column :xml, :text
  t.column :created_at, :datetime
  t.column :amazonable_id, :integer
  t.column :amazonable_type, :string
end

Example:

$ cklog access_log

04-15-2007: 21
04-16-2007: 2134
04-17-2007: 304
04-18-2007: 6960
04-19-2007: 951
04-20-2007: 412

Here’s the script:

require 'date'
 
daily = Hash.new
File.open(ARGV[0] || "access_log", "r") do |file|
  while line = file.gets
    if line =~ /(\d{2}\/\w{3}\/\d{4}).*GET\s([^\?\s]+)/
      date = Date.strptime $1, '%d/%b/%Y'
      daily[date] = 0 if daily[date].nil?
      daily[date] + 1
    end
  end
end
 
daily.sort.each {|d, f| 
  puts "#{d.strftime '%m-%d-%Y'}: #{f}"
}

You can run this as a stand-alone script and just pass in the URL to crawl as an argument.

[ruby]
require ‘net/http’
require ‘uri’

class SiteCrawler
def initialize(url)
@site_uri = URI.parse(url)
@site_uri.path = “/” if @site_uri.path == “”
@visited = Hash.new
@queue = Array.new
addPath(@site_uri.path)
puts “Initialized site crawl for #{@site_uri}”
end

def addPath(path)
@queue.push path
@visited[path] = false
end

def getPage(path)
begin
uri = @site_uri.clone
uri.path = uri.path + path if path != “/”
puts “getting #{uri}”
response = Net::HTTP.get_response(uri)
rescue Exception
puts “Error: #{$!}”
return “”
end
return response.body
end

def queueLocalLinks(html)
html.scan(/ uri = URI.parse("#{w}")
if !@visited.has_key?(uri.path) and
(uri.relative? or uri.host == @site_uri.host)
addPath(uri.path)
end
}
end