There's been a lot of supposition about the future lately, and I've certainly read and succumbed to the temptation of the prognosticator. I'm not going to comment on any of the players or put forward my own suppositions about what might happen. What I will do here is talk about what *should* happen.
It's apparent that the Java platform is at a crossroads. One path leads to irrelevance, be it through general apathy that important technologies are getting sidelined, or through active emigration due to bureaucratic processes and waterfall platform evolution. The other path leads to a bright, open future, where polyglots romp and play with fresh new languages and developers have freedom to use whatever tools they feel are necessary for a given job. Given the large investment many of us have in this platform, we need to start talking now about which direction we want to go.
I've been doing a lot of thinking about the future of the Java platform and my future developing for it, and I've come up with a few things I believe must happen soon to ensure the future of the JVM and the applications and languages built for it.
As you might expect from me, the first area involves supporting many languages on the JVM. Over the past three years we've seen a spectacular transformation take place. The "Java" VM has become a truly multi-language platform. People are putting into production applications running all sorts of languages, often writing absolutely no Java to do so. And this is how things must be...this is how the platform is going to survive.
As I see it there are currently three primary players in the language domain: JRuby, Scala, and Groovy (in no particular order). I include these three due to the relative completeness of their implementations, vague popularity metrics, and availability of production use cases. These three languages, one static and two dynamic, bear further exploration.
JRuby represents the promise of off-platform languages being brought to the JVM. Rather than creating a language specifically tailored to fit well into the JVM's type system and limitations, we have managed to take a drastically different language and implement enough of it to be the only "alternative" implementation realistically considered for production applications. And in doing so we've had to stretch the platform. We've created native binding libraries, wired in POSIX functions the JDK doesn't provide, implemented our own core types like Strings, Arrays, and regular expressions, and done all this while managing to deliver the best performing compatible Ruby implementation available. And where the other two primary language contenders largely pull developers from other areas of the Java platform, JRuby actually brings in many developers that might not otherwise ever use the JVM. JRuby stretches and grows the platform.
Groovy is the second dynamic language under consideration. Groovy represents taking the best features of a number of dynamic languages and wiring them into a Java-like syntax that's easy for existing Java developers to learn. Groovy provides a solid dynamic language foundation without breaking Java type-system requirements like ahead-of-time compiled classes and static method signatures, allowing it to enlist directly in newer APIs that depend on those requirements. And while many developers come to Groovy from other areas of the Java platform, they might also have completely left the platform if not for Groovy. Groovy provides for Java developers a "dynamic layer" that doesn't require them to learn a new platform and a new set of libraries. And so Groovy's strength is in maintaining the platform and stemming the bleeding of developers to off-platform dynamic languages.
Scala, it must be stated, is the current heir apparent to the Java throne. No other language on the JVM seems as capable of being a "replacement for Java" as Scala, and the momentum behind Scala is now unquestionable. While Scala is not a dynamic language, it has many of the characteristics of popular dynamic languages, through its rich and flexible type system, its sparse and clean syntax, and its marriage of functional and object paradigms. The supposed weakness of Scala as being "too complicated" or "too rich" can be countered by developing coding standards, creating more robust editors and tools, and by better educating polyglots on how best to use Scala. Scala represents the rebirth of static-typed languages on the JVM, and like JRuby it has also begun to stretch the capabilities of the platform in ways Java never could.
Among the secondary players I include language implementations like Jython, Clojure, and Rhino. While still in early days of adoption (or in Jython and Rhino's cases, early days of re-awakening), they represent similar aspects to the primary three languages. For purposes of discussion, we'll leave it at that for now.
In order for the platform to embrace these and many future languages, several things need to happen:
- Ongoing work on these languages must be funded in such a way as to avoid product lock-in. Funding them by tying them to specific technologies will only fracture development communities, and likely damage any existing open-source contributor base.
- There must be paid support offerings for these languages outside of specific products. For people interested in running JRuby on Rails, Grails, or Liftweb, there must be support channels they can follow, regardless of product bundling attempts. In the JRuby world, for example, we receive many requests for paid support, either in the form of hired guns to optimize an application or through targeting resources to critical bugs. And so far, we have been unable to offer such support.
- We must continue the work started on the OpenJDK and MLVM projects. OpenJDK has enabled such projects as Shark (Hotspot on LLVM) and the MLVM (JVM extensions for non-Java language features), and we must see these efforts through to completion.
- Finally, we need a "languages czar" that can coordinate the technical aspects of these various projects and help direct resources where needed. This would largely be a community-cultivating role, but as a sort of "open-source manager" to ensure development efforts are both cooperating and not being needlessly duplicated.