Originally posted as a gist in response to this twitter conversation.

I’m working on a Rails application that uses the Exchange Webservices API. Unfortunately the EWS API has a weird package, but I thought that wouldn’t be hard to overcome. So I wrote this script:

require 'java'
require 'vendor/lib/EWSJavaAPI_1.2.jar'

def microsoft
  Java::Microsoft
end

version = microsoft.exchange.webservices.data.ExchangeVersion::Exchange2010_SP1
service = microsoft.exchange.webservices.data.ExchangeService.new(version)

Getting the ExchangeVersion enum worked fine, but trying to access the ExchangeService class resulted in this error:

NameError: missing class or uppercase package name (`microsoft.exchange.webservices.data.ExchangeService')
get_proxy_or_package_under_package at org/jruby/javasupport/JavaUtilities.java:54
method_missing at file:/Users/adam/.rvm/rubies/jruby-1.7.3/lib/jruby.jar!/jruby/java/java_package_module_template.rb:14
(root) at lib/sandbox.rb:11

I thought the problem was with the package name, but the error is actually that the EWS API is missing its dependencies. It needed commons-httpclient and commons-logging-api on the classpath. I discovered this via clojure’s error message for similar code:

(import '(microsoft.exchange.webservices.data ExchangeService))
ClassNotFoundException org.apache.commons.httpclient.HttpConnectionManager  java.net.URLClassLoader$1.run (URLClassLoader.java:366)

So the real issue here is JRuby’s error message. Interestingly enough, JRuby did give me a better error once commons-httpclient was on the classpath:

MultiThreadedHttpConnectionManager.java:70:in `<clinit>': java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory

That told me commons-logging-api was also missing. JRuby should have told me that in the first place.