Dalvik: how Google routed around Sun's IP-based licensing restrictions on Java ME

Stefano Mazzocchi

November 12, 2007

Sun released their "free java [ http://openjdk.java.net/ ]" source code under the GPLv2 [ http://www.fsf.org/licensing/licenses/info/GPLv2.html ] to both win the free software crowd and capture peripheral innovation and bug fixing from the community. For the java standard edition (aka "the cat is out of the bag") there is an exception to the GPLv2 [ http://openjdk.java.net/legal/gplv2+ce.html ] that makes it "reciprocal" only for the Java platform code itself but not for the user code running on it (or most people wouldn't even dare touching it with a pole).

But such exception to the GPLv2 is not there for the mobile edition [ https://phoneme.dev.java.net/phone_me_faq.html#cldc5 ] (aka "where the money is").

This brilliant move allows Sun to play "free software paladin [ http://arstechnica.com/news.ars/post/20070228-8938.html ]" on one hand and still enjoy complete control of the licensing and income creation for the Java ME platform on mobile and embedded devices on the other (because cell phone makers would rather pay than being forced to release all their code that runs on the phone under the GPLv2... or, in many cases, they can't even if they wanted to as they don't own the entire software stack).

Which is also why their TCK license [ http://www.sun.com/software/opensource/java/faq.jsp#k3 ] they offer for free to Apache [ http://www.apache.org/ ] to certify Harmony [ http://harmony.apache.org/ ](which is a 'standard edition' implementation but could be easily turned into a mobile edition one) includes 'field of use' restrictions. It's funny that Sun's own CEO considers the very same 'field of use' restrictions ridiculous [ http://blogs.sun.com/jonathan/entry/harvesting_from_a_troll ](but this is it is Sun to have such field of use restrictions applied on them), but Sun imposes them nevertheless and no open letter has been able to change their position [ http://www.apache.org/jcp/sunopenletter.html ].

This is the stall in which Google [ http://www.google.com/ ] announced [ http://www.openhandsetalliance.com/press_110507.html ] the release of their Android platform [ http://code.google.com/android/ ], which would be able to run Java applications on a mobile phone but it would also be released under the Apache License v2 [ http://www.apache.org/licenses/LICENSE-2.0.html ].

This raised more than one eyebrowse [ http://redmonk.com/sogrady/2007/11/05/android-the-gpl-and-java-the-qs-with-no-as/ ], and sure did make me raise mine: how did Google manage to get Sun to license off a platform that could very well kill their own?

Turns out, they didn't: their move was even smarter than Sun's.

Today Google released the Android code and I took a serious look at its internals... and found the solution for the licensing problem. It's called Dalvik and it's the new name of Sun's worst nightmares.

Dalvik is a virtual machine [ http://code.google.com/android/what-is-android.html ], just like Java's or .NET's.. but it's Google's own and they're making it open source without having to ask permission to anyone (well, for now, in the future expect a shit-load of IP-related lawsuits on this, especially since Sun and Microsoft signed a cross-IP licensing agreement on exactly such virtual machines technologies years ago... but don't forget IBM who has been writing emulation code for mainframes since the beginning of time).

But Android's programs are written in Java, using Java-oriented IDEs (it also comes with an Eclipse plugin)... it just doesn't compile the java code into java bytecode but (ops, Sun didn't see this one coming) into Dalvik bytecode.

So, Android uses the syntax of the Java platform (the Java "language", if you wish, which is enough to make java programmers feel at home and IDEs to support the editing smoothly) and the java SE class library but not the Java bytecode or the Java virtual machine to execute it on the phone (and, note, Android's implementation of the Java SE class library is, indeed, Apache Harmony's!)

The trick is that Google doesn't claim that Android is a Java platform, although it can run some programs written with the Java language and against some derived version of the Java class library. Sun could prevent this if they had a patent on the standard class library, but they don't and, even if they did, I strongly doubt it would be enforceable since Android doesn't claim to be compatible (and in fact, could very well claim that their subset/superset is an innovation on the existing patent and challenge Sun's position).

Not only this allows Google to avoid having to battle thru the JCP [ http://jcp.sun.com/ ] for any change to the Java ME "standard" or tolerate Sun's unique ability to veto any JCP change, but gives users a much more 'fresh [ http://code.google.com/android/images/system-architecture.png ]' and modern class library to play with and built-in hooks to all the hardware features of your phone, including things like OpenGL, bluetooth, USB and all those things, which don't come with the standard Java ME and therefore cannot be taken for granted by the developers.

So, here we are: Apple [ http://www.apple.com/ ] makes the iPhone [ http://www.apple.com/iphone/ ], incredibly sweet, slick and game-changing and yet incredibly locked. Google makes Android and not only unlocks development abilities on the mobile phone but also unlocks millions of potential Java mobile programmers from Sun's grip on it.

Plus, they're targeting 3G phones, not the crappy 2.5G that the iPhone supports now.

Screw the iPhone and screw Java ME with all its profiles, midlets and the stupid requirement to crypto-sign your application to run on your own phone: I can hardly wait to get my hands on hardware that can run Android... and if they can't support multi-touch out of the box because Apple owns patents on it [ http://www.macobserver.com/article/2006/10/09.2.shtml ], I'll download the patch that enables it from a country where such nonsense doesn't apply.

15:10

Update and Errata (a few things worth pointing out):

The Android SDK does not compile your Java source code into Dalvik's bytecode directly, but it first uses a regular java compiler to generate regular java bytecode (say, javac or the built-in Eclipse compiler) and then converts that bytecode into Dalvik's bytecode (the "dx" tool does this: convers .class/.jar into .dex files). Still, the substance remains: there is no need to ship a java virtual machine on your Android-powered phone and you can use your regular Java standard edition to develop your phone application (means, you don't need to use Java ME anywhere at all).

Google has released the binary SDK for Android and only the source code for the examples. It did indeed contribute patches to the Linux kernel to support 3G Qualcomm chipsets (under the GPLv2, so that it wouldn't create a impedance mismatch in the kernel ecosystem) but it has not, to this day, released the source code for Android itself even if it has explicitly claimed in their announcement that they will do that in the future and under an Apache License v.2. I strongly doubt this will include source to every single piece of the Android middlewere (the video codecs seem the hardest part to relicense) but I really hope that the Dalvik VM itself will be open sourced or a lot of the appeal of this platform will just vanish.

A good friend reminded me that there is no such thing as "routing around" IP licensing restrictions and that bigco routinely use shake-up moves like these to re-establish alliances or to call other bigco's bluff. It is worth nothing that Sun has never made available a public list of the IP they own and that you need to license in order to legally be able to run Java (personally, I think they don't know themselves: such things are really tricky to figure out, even internally). All their licensing deals (including the one with Microsoft [ http://www.sun.com/smi/Press/sunflash/2004-04/sunflash.20040402.3.xml ]) have been broad and very general and there is no way for us of knowing if Android infringes even just one of the patents that Sun owns around the Java platform (my friend suggests java's internal security manager, which is clever and original, but that depends on whether Dalvik supports the same model or a sufficiently different one to stand in court).

The Apache License v2 forces the contributor to license the IP along with the code but only the IP that the contributor owns (you can't give away stuff others own, obviously). This means that if Android does, in fact, use some of Sun's IP, it is entirely possible for Sun to sue any hardware vendor that ships Android with their phones and prevent them from shipping. Also, Sun could knock at your own door and ask you to license the Java IP that you need to be able to run Android on your phone (in case, say, you bought an OEM phone and installed the software yourself) even if there is no trace of 'java' on your phone memory.

Sun is under fire for IP issues related to ZFS [ http://radar.oreilly.com/archives/2007/11/suns_counteratt.html ] and they claimed that it's an "attack on free software". I'm curious to see how they're going to spin their own IP attack on Android (because I bet there's going to be one).