Ruby on Rails with Spring, Hibernate and JPA

scottned — Fri, 23 Jan 2009 18:56:42 +0000

I’m leading a discussion on this topic at the Charlotte BarCamp tomorrow.

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.

Accessing a Java AXIS web service with Ruby and SOAP

scottned — Mon, 12 Feb 2007 19:04:38 +0000

I’ve been working with soap4r in Ruby to access some Java web services which use AXIS 1.1. The particular api I’m accessing requires an initial authentication call which returns a token that must be passed in all subsequent SOAP headers. This is a pretty common scenario, but it took me awhile to get it working correctly.

There were basically two “tricks”. The first which I found on a few other blogs entails creating a HeaderHandler (some suggested SimpleHeaderHandler, but that didn’t work for me because of trick #2). Here’s what I ended up with:

class ClientAuthHeaderHandler < SOAP::Header::Handler
  HEADER = 
    XSD::QName.new('http://www.foo.com/SecurityPass', 
                             'SecurityPass')
 
  def initialize(token)
    super(HEADER)
    @token = token
  end
 
  def on_outbound
    el = SOAP::SOAPElement.new(HEADER, @token)
    el.extraattr['xsi:type'] = "xsd:string"
    SOAP::SOAPHeaderItem.new(el, false)
  end
end

The second “trick” was in the on_outbound method. What I found was that AXIS was requiring the xsi:type to be included in the header that I added or it wouldn’t be recognized. Using extraattr was the only way I could figure out how to coerce it to be included. I suspect at some point this will be unnecessary, but for now it did the trick.

Here’s a simple example:

class FooService
  # pass STDOUT to wiredump to see messages
  def initialize(uri, wiredump=nil)
    @uri = uri
    @wiredump = wiredump
  end
 
  def svc(ref)
    ws = SOAP::WSDLDriverFactory.new("#{@uri}#{ref}?wsdl").create_rpc_driver
    ws.wiredump_dev = @wiredump
    ws.generate_explicit_type = true
    if !@sec_token.nil?
      ws.headerhandler << ClientAuthHeaderHandler.new(@sec_token)
    end
    ws
  end
 
  def authenticate(username, password)
    ws = svc("/services/AuthenticationService")
    @sec_token = ws.authenticate(username, password)
  end
 
  def lookup(stuff)
    ws = svc("/services/LookupService")
    ws.lookup(stuff)
  end
end

Netphase » java

Ruby on Rails with Spring, Hibernate and JPA

Accessing a Java AXIS web service with Ruby and SOAP