This is a problem that I have faced a couple of times and every time I spend a few hours futzing with Apache configurations trying to get this to work. So I figure I should post the basic solution and never have to look hard for it again. Also, if someone has better suggestions, let me know.

Step 1: Activate the Requisite Modules

I use four modules for getting this to work

• mod_alias
• mod_proxy
• mod_proxy_http
• mod_rewrite

Make sure these are activated in your configuration

Step 2: Setting Up The Static Content

First step is to set up a directory location that will ahve the content. In my example, I am dealing with an exploded EAR in the Jboss home directory. This results in a configuration like

#
# Configure the static content directory and alias.  This is pointing at the cache
# file directory
# 

Alias /static-content/ "/usr/local/jboss/cache/app" 

#
# Do not allow any overriding from within the cache directory. #
<directory /usr/local/jboss/cache/app" >
  Options None
  AllowOverride None
  Order allow,deny
  Allow from all
</directory>

Step 3: Set up the rewrite rules

#
#  Rewrite all static content  to be served from the
#  static content directory
#
<IfModule mod_rewrite.c<
    RewriteEngine on 

    #
    # Setup the static content rule.  Any file that comes in that# we have on the filesystem, we should serve from there.
    #
    # We want this to be the last rule processed if we meet the conditions
    # and we need to pass through so that the static-content alias works.
    #
    RewriteCond /usr/local/jboss/cache/app/%{REQUEST_FILENAME} -f
    RewriteRule ^/?(.*)$ /static-content/$1 [L,PT]
</IfModule> 

<IfModule mod_proxy.c>

# No need to forward proxy
ProxyRequests Off 

# Make sure we clean up the headers
# you may also wish to use the mod_proxy_ajp to proxy
# over the ajp protocol

  ProxyPassReverse / http://localhost:8080/ 

# Needed to maintain proper host information
  ProxyPreserveHost On
</IfModule> 

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• President of my own company, 416 Software
• Adjunct Professor for Penn State
• Interim VP of Engineering for an unnamed startup doing cool things with email
• Build/Release/JBoss Expert
• General Software Consultant

but for my latest title….

Management Consultant.

Good to know someone takes my ranting seriously!

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Probably my favorite example was an expansion on a previous blog post about using JRuby and HtmlUnit.  In the presentation, I created a simple Domain Specific Language on top of the great HtmlUnit library to allow for simple parsing of pages with content in JavaScript.  This was a great example of how JRuby can be used to take advantage of both Java and Ruby

The presentation is available at http://www.innovationontherun.com/presentation-files/Introduction%20to%20JRuby-10-23-2007.pdf and the associated source code can be found at http://www.innovationontherun.com/presentation-files/JRuby-JUG.zip.  If you are looking at the source code, start with the file ABOUT.txt.  It describes the prerequisites needed to get the code to run and the order of the listed files follows the order that they were used in the presentation.

If you have questions or comments, feel free to send me an email.

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For the unaware, Embedded JBoss allows a developer to embed much of the functionality of the JBoss application server (EJB, Messaging, JNDI, Security, Transactions) in another application.  A great use for the technology is in the creation of unit tests that can actually test Session, Entity, and Message Driven Beans.  At Health Market Science, we heavily used the Embedded EJB container (a predecessor to Embedded JBoss) connecting to a in-memory Hypersonic DB for improving out unit tests.  It made developing and debugging significantly easier and all of the developers loved doing it.  I highly encourage any developer that is developing using EJB3, and especially anyone using JBoss, to use the combination of Embedded JBoss.

Full Presentation can be found at http://www.innovationontherun.com/presentation-files/Intro%20to%20Embedded%20JBoss.pdf

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Class not found: [Ljava.lang.String;

What the hell?  Of course I initially assume it is something I did wrong, then that it is something in the JBoss configuration.  After much anguish and googling, it turns out there is an awesome bug/feature in Java 1.6 where the following code (which worked in Java 1.5) throws a ClassNotFoundException in Java 1.6.

  public class test {

      public static void main(String[] args) throws Exception {
          String[] s = new String[] { “123″ };
          String clName = s.getClass().getName();
          test.class.getClassLoader().loadClass(clName);  // throws exception in JDK 1.6!
      }
  }

But the lameness did not stop there.  The next issue that popped up was a NullPointerException when trying to read a file.  Turns out there is a bug on Windows XP with directory names involving spaces.  I was running it off of my desktop, c:\Documents and Settings\rdimarco\Desktop.  Moving the application to the c:\jboss directory solved my problems.  I’m not sure if it is a JDK or JBoss bug, but at this point I’m just frustrated.

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So how should a developer operate as a CEO?  What do they need to think about.  What questions do they need to have answered?  Let’s discuss a couple required characteristics of a good CEO and then apply them to your career path.

SIDENOTE: Often, when we think of career growth, we equate growth to earning more money or a getting a better title.  These may be evidence of growth, but are not requirements.  Career growth may also involve trying new technologies, changing roles, or changing industries.  It may mean getting out of technology

Taking Responsibility

You, and only you, are responsible for your career path.  Accept this.  It is not your boss’s job to get you trained on new technologies, it is your responsibility to make this happen.  Figure out what you would like to learn and then ask your boss to help you make it happen.  If you do not take responsibility for asking, it is very unlikely that you will get what you want.  Regardless of whether your employer will pay for your education, do it anyhow.  Learn a new language (programming or foreign).  Read books and then apply them to your work.  Go to an interesting conference.  While it is definitely preferred for your boss to play a part in what languages you learn or what books you read, it is your responsibility not your boss’s to make it happen.

Determine Strengths

What are you good at doing?  Drucker posits that the only way to figure this out is by using feedback analysis.  He suggests that after every key decision or action that you make, write down what you expect the result to be and then review it in 9 to 12 months.  See if there are patterns between where you anticipated the results and where you did not.  From this feedback, figure out what you are good at and what you need to improve.  In addition, you may see things that you have no business doing.  For example, software developers often make atrocious project managers.  For some, this may because they lack training in the area; for others it may be that they lack the ability to develop an effective plan.  By looking at how you have done, you can see if consistent lack of planning is a problem and try to figure out if you can improve it or if you need others to help you with it.

In addition, look at how you operate outside of just writing code.  Take the opportunity to learn about things that extend outside your area of expertise.  Read books on marketing principles, go out on sales calls, take a basic class on accounting.  Improving yourself in non-technical areas will help you better understand demands on your co-workers and you may find that you have strengths in areas you never anticipated.

Know Your Core Values

Core values are the things that you feel are truly important to you; they are different than ethics.  Ethics relates to doing what is right.  Values relate to doing what you believe in.  For example, one of my key values is that I feel you should only hire the very best technical resources, that these resources should have problems explained to them and then should be empowered to make decisions as to how to best solve the problems.  The corporation I was working for decided to take a different philosophy where the business users were more responsible for deciding how to solve the problem.  That may be the right decision for the organization, but it violated my personal values.  Other examples of value decisions a company will need to make may include:

• The level of R&D investment to make
• Use and contribution to open source software
• Whether people should be compensated by stock options or by cash
• What accounting rules to use to recognize revenue
• Support for telecommuting

Just because you may disagree with a company’s values does not mean it is a “bad” company.  But trying to stay in an organization that has values that conflict with your values will only lead to frustration.

Planning for the Future

Take some time to think about what you where you want to be in five years.  Figure out what skills and experiences you will need to achieve this goal.  Write down what it will take and review the list regularly.  Another great suggestion that Drucker has is to have a hobby.  You never know if that hobby will lead to a second career.  After twenty years working with technology, you may lose your passion and you may be prefer a change in career direction.  By encouraging other interests, you may find that your desired career path is no longer in technology but is in another area

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The hardest part of the development has been trying to debug why the hell all of the scripts have been failing.  Most of the problems seem to fall into one or more of a few categories:

• Hacks in the YUI libraries to deal with the fact that IE and Firefox both operate differently and NEITHER is fully compliant with the DOM specification.  That has made for lots of fun times.  I have found a certain irony that I am cursing the Yahoo developers for the hacks that they wrote while probably cursing
• Bugs with the Rhino JavaScript libraries.  For example, I could not even start the YUI tests until I upgraded to 1.6R6.  Also, I think I found a subtle bug that is causing one of the unit tests to fail related to the for…in syntax, but it has been a bitch to reproduce.
• No integrated debugging of the JavaScript code.  The only way I can diagnose what is really breaking is by liberal use of the alert() method and then a review of the output.  Hopefully this will change in Rhino 1.7.  Huge problem.
• Unhelpful error messages.  For example, I was getting a NullPointerException being thrown from SOMEWHERE in a script, but the stack trace was lost when it was transformed to a ScriptException.  The only way I was able to debug the problem was to put a breakpoint on the constructor for NullPointerException and then look at the runtime stack when it was thrown, then grep through the Yahoo JavaScript to try to figure out where the problem could possibly be.

So if you ever having to work with the implementation

• Make sure you are using a good IDE with a debugger.  I cannot stress this enough.  I have had to put breakpoints all over the damn place.  And integrate as much of the source code around as you can and integrate it with the debugger.
• If you are using Java 6, I would STRONGLY RECOMMEND NOT USING THE DEFAULT SCRIPTING IMPLEMENTATIONS!!!  I have now worked with both the JRuby and JavaScript libraries.  It is way easier to upgrade versions of your libraries to work around bugs if you are using the standalone implementations rather than the versions built into the JVMs.  By the way, how much fun will it be when a later version of Java comes out with new scripting libraries that I am sure will not be 100% backwards compatible.
• Take Mozilla, MSDN, and especially W3C reference documents with a grain of salt.  They may not fully describe the behavior that you are seeing in the browser.

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