A large underwater earthquake ends up creating an effect called a tsunami. The event can be detected by sensors around the world, but the resulting tsunami isn’t immediately visible; if you’re in the surrounding ocean you’ll notice it, but it’s only when it hits land that you really notice the effect.

On May 8, 2007, there was an effect a lot like an underwater earthquake in the software world. What are we talking about? The complete release of OpenJDK, of course. Since that time, we’ve mostly been in the underwater propagation stage. A lot has been happening behind the scenes such as removing proprietary bits, fixing OS integration, etc. But now, I think we’re close to moving into the stage where the ocean recedes, so you can see the first visible effects.

The original OpenJDK release was a snapshot of the in-development version 7, so it was not quite suitable as a drop-in replacement for software that was targeting JDK 6. But recently in February, Sun released the sources to the stable version of the JDK, version 6. Thanks to the combined work of the OpenJDK team and the IcedTea project, this is now suitable to effectively work as a drop-in replacement for the earlier proprietary JDK releases.

On Fedora 8, this command worked for me:

sudo yum --enablerepo=development install java-1.6.0-openjdk

It pulled in new versions of a few things like zlib, but no big deal. In any case I think you’ll likely see OpenJDK 6 pushed as an update for Fedora 8 too.

Why is this so important?

It’s pretty hard to underestimate the transformative impact Java and the JVM have had on the software industry in the last decade or so. Now, Java is a very well designed language, but what I think is equally (if not more) important is the JVM. The JVM was really pretty far ahead of its time; the optimizing JIT compiler, the class structure, the threading model, concurrent generational garbage collection, etc.

There has been quite a lot of innovation on top of that platform. Ok, that sounds a bit buzzword-y. How about this: People have written a lot of awesome software for the JVM.

The examples seem endless; but let’s mention some:

• Processing – a combination language and mini-IDE designed for creating visual effects
• NASA’s World Wind
• Groovy, which is along with Boo in my opinion one of the top contenders for the next-generation of programming languages
• MIT SIMILE projects like Welkin.
• Hibernate – Best-in-class object-relational mapping
• Eclipse
• Hadoop – Free Map/Reduce implementation

Impact ahead

But before OpenJDK, most of these projects effectively did not exist to the core of Free Software community. Even though all of these projects are themselves Free Software, to run it you had to download and install proprietary JDK. I think for most of us, we might as well have been required to download a Windows or OS X VM. At least that’s the way I felt. It wasn’t very integrated with the operating system. But most importantly, it was a blob which we didn’t ultimately control, and we were right to avoid the Java Trap.

But, those were pre-earthquake times. The integration of the formerly-separate Java/JVM world with the Free Software community is ramping up very quickly. For example, Fedora is close to landing all of the dependencies of JRuby. I don’t think anyone has started on things like Processing or World Wind yet – it could be you!

A shared Free Software runtime

I want to talk specifically about efforts like JRuby, and the newly-invigorated Jython. In an earlier blog entry, we looked at the fragmentation in the Free Software community. Every free language has its own runtime and libraries; and until now, building on the JVM wasn’t an option if you wanted many contributors from the Free Software world. OpenJDK is finally changing that. Now, you can write a library using Java, it can be sensibly integrated with Free operating systems like Fedora, and can be consumed by anything on the JVM, which includes Python and Ruby, as well as new languages like Groovy. We’d actually be sharing more than just the OS kernel and C library.

Crucially, this is a platform we now control, because it’s Free Software. And the original upstream is not just giving some standards or source code drops, they are actively helping us. In fact, “they” are “us” now!

Part 2 of this entry