Blogging Roller

Roller 5 and JBoss 6

Dave Johnson — Thu, 20 Jan 2011 18:00:15 +0000

In my quest to make Roller work on Java EE 6, the next server that I tackled was JBoss 6. In this blog I'll describe how I approached the problem what I learned along the way.

Tested with Hibernate JPA

Roller uses JPA for database storage and specifically the Apache OpenJPA implementation. I knew that JBoss uses the Hibernate JPA implementation and I suspected that there would be JPA portability problems, so I decided to run Roller's JUnit tests against Hibernate JPA. There were many test failures and fortunately, the failures were easy to fix.

Where OpenJPA is lenient, Hibernate JPA is strict about declaring transients fields as transient. So, wherever Hibernate complained, I added the appropriate transient declaration and soon all tests were passing. There were a lot of changes, but they were all trivially easy. Since I first "ported" Roller to ElipseLink JPA, its possible that some of the changes I made for EclipseLink helped with the port to Hibernate JPA.

Those of you who are familiar with Roller's history might remember that this is the second time I worked to make Roller work with Hibernate. Early versions of Roller ran on Hibernate until Roller 4, when we ripped it out because Apache policy does not allow LGPL. With Java EE 6, Roller can run on Hibernate and we don't have to ship the Hibernate jars to do so.

Tried using the Java EE version of the Roller WAR

Since JBoss 6 is a Java EE 6 server, just like Glassfish, I figured I could use the same WAR that I created for Glassfish. That didn't really work out, as you will see below. When I attempted to deploy the Roller WAR to JBoss I ran into two problems:

Problem 1: Xerces and JavaAssist

When I tried to deploy the Roller WAR to JBoss, I ran into class-cast exceptions that indicated that the version the the Xerces XML parser included with Roller conflicts with the one that is included in JBoss. I encountered a similar problem for the JavAssist jars, which are also part of Roller. This was quite surprising to me. Apparently, JBoss uses Xerces and JavAssist internally and for some reason the JBoss internals bleed through and interfere with applications; seems like a bug to me. So, we have to have a special Roller WAR for JBoss without the Xerces and JavaAssist jars in the Roller WAR.

Problem 2: JNDI Datasource Name

The next problem that I encountered was the datasource name. Roller uses the JNDI naming API to lookup its JDBC datasource. In all of the other app servers, we tell people to setup a datasource with the JNDI name 'jdbc/rollerdb' but that name did not work for JBoss. For JBoss, I could only get names of names of the format "java:/name" to work. Unfortunately, with JPA the datasource name must be embedded in the persistence.xml file which is embedded in a JAR file which is embedded in the Roller WAR file. It's in there deep, so we have to produce a special Roller WAR for JBoss with a JBoss-friendly datasource name.

*Please* correct me if I'm wrong. I would love to be wrong about either of these two problems.

Created special Roller WAR just for JBoss

Due to those two problems, I modified the Roller build process to create a special Roller WAR for JBoss without the OpenJPA, Xerces and JavAssist JARs and with the JBoss friendly JNDI name java:/RollerDS inside all included persistence.xml files.

Deployed, tested and updated the docs

Once I worked around those two problems, installing Roller on JBoss was easy. I did the whole thing via the JBoss web console, which was not familiar to me but was pretty easy to understand and use. I documented the whole process in the Roller 5 Install Guide (2MB PDF), with screenshots.

Next up: Roller 5 on WebSphere 8 (beta)

Roller 5 and Java EE 6

Dave Johnson — Wed, 5 Jan 2011 08:15:53 +0000

It's hard to believe, but I've been dorking around with Roller, the blog software that powers this site, for almost 10 years now. I started in summer 2001. In the past couple of years, I've had a lot less time to work on Roller. I devoted some of that time to mentoring student developers, which was fun and rewarding. I also spent time making Roller more consumable for developers by making it easier to build, run and deploy to modern Java app servers, which was not really fun but was definitely educational, bloggable even.

Roller 5 as Java EE 6 case study

Making Roller work on the new crop of "modern" Java EE 6 servers was an interesting experience and the story makes a pretty good case study in Java EE application portability. I've put together a short series of blog posts to tell the story and this is the first, an overview. In subsequent posts I'll explain the changes I had to make to get Roller working on:

	GlassFish 3 (released June 2010)
	JBoss 6 (released December 2010)
	WebSphere 8 (beta released July 2010)
	Tomcat 6 and 7 (not Java EE but Roller just has to work on Tomcat)

There are other Java EE 6 servers out there and there's a good summary of them on The Aquarium; those are just the ones I had time to explore.

Overview of Java EE 6 changes

There were three categories of things I changed to accomodate Java EE 6 servers. The first is changes to the Roller code base to make Roller work on all of my targets. Most of these changes were in way Roller uses calls the Java Persistence APIs (JPA), needed because of differences in the JPA implementations used by each server. GlassFish uses EclipseLink JPA and JBoss uses Hibernate JPA. On WebSphere and Tomcat, Apache OpenJPA is the implementation. Fortunately, nowhere did I have to use any conditional code or introduce special behavior for any platform.

The second category of changes is additions to the Roller install guide to mention the special settings required to make Roller work on all targets. On some platforms, special behaviors must be enabled for Roller, for example the "filter compatibility" flag on WebSphere. I added a section to the install guide for each server and documented the details there.

The third category is changes to the Roller build process to create special versions of Roller for some servers. Unfortunately, due to Tomcat not being a full Java EE server and some JBoss classloader issues, I'm not able to provide one Roller release that runs on all servers. The latest Roller 5 release candidate comes in three flavors, one for Tomcat 6/7, one for JBoss 6 and one for "Java EE" which is the one intended for use with Glassfish 3.1 and WebSphere 8.

Up next: GlassFish 3

In the next post I'll tell you what I had to do to get Roller running on Glassfish 3 with EclipseLink JPA.

Apache Roller 5.0 RC3

Dave Johnson — Tue, 4 Jan 2011 08:00:00 +0000

On the last day of 2010, I made available the third release candidate for Apache Roller 5.0. The main difference between this new candidate and the previous one is that the new RC3 runs on Java EE 6 servers: Glassfish 3, JBoss 6 and Websphere 8 (currently in beta). Making this happen took a lot more work than I expected and I'll blog about that over the next couple of weeks as it is an interesting case study in Java EE 6 portability.

Here's the announcement:

Apache Roller 5.0 Release Candidate RC3 is now available for testing.
Note that this is NOT a release of the Apache Software Foundation or
anybody else; this release candidate is for testing purposes only and
not recommended for production.

   What's new in Roller 5.0:
   https://cwiki.apache.org/confluence/display/ROLLER/What's+new+in+Roller+5.0

   Change list (issues resolved since 4.0)
   http://bit.ly/gAhDWR

   Issues resolved since last release candidate (RC3)
   http://bit.ly/dZ27Nx

   Signed binary and source files. Also, documentation in PDF form
   http://people.apache.org/~snoopdave/apache-roller-5.0/

The biggest change in RC3 is the new support for Java EE 6 application
servers: Glassfish 3, JBoss 6 and Websphere 8 (beta). I've been able
to verify that Roller runs on all of those servers, and I updated the
installation guide to explain in detail how you install on Glassfish,
JBoss and WebSphere.

If you would like to help out then please test RC3, discuss the
problems you encounter here and file specific bugs with steps to
reproduce in the Roller JIRA bug tracking system.

Thanks,
Dave

That announcement is available here: http://markmail.org/message/my5wbld2xqvhqpyg

Despotism at JBoss.org

Dave Johnson — Thu, 8 Feb 2007 09:51:33 +0000

And I mean that in the nicest way possible, i.e. the Codehaus way.

Bob McWhirter: Ultimately all open-source survives and grows based upon goodwill. Tending to the community is required, else you risk alienating your own users. I aim to use my experiences from a variety of open-source projects and communities to make sure the JBoss community is one of which Iâ€™m proud to be a member.

Congrats Bob. Sounds like a great new job. This mean you'll be coming to Raleigh more often?

JBoss sanitized blogs before aquisition?

Dave Johnson — Mon, 10 Apr 2006 13:01:28 +0000

Back in 2004 I linked to a blog post authored by JBoss exec Mark Fleury that called Red Hat "open source wannabes" and "girly men." According to my referrers, people are looking for that old post using those keywords. Apparently, they're not finding it because it's been removed (but not from the ~~Google Cache~~ Wayback Machine). I wonder why.