Classpath Exception not included in the mobile edition [LWN.net]

Classpath Exception not included in the mobile edition

Posted Aug 18, 2010 10:46 UTC (Wed) by paulj (subscriber, #341)
In reply to: Classpath Exception not included in the mobile edition by dgm
Parent article: A very grumpy editor's thoughts on Oracle

That's not true, OpenJDK is under a GPLv2 + "ClassPath Exception" licence. Here's the text of that exception:

"CLASSPATH" EXCEPTION TO THE GPL
Certain source files distributed by Sun Microsystems, Inc. are subject to the following clarification and special exception to the GPL, but only where Sun has expressly included in the particular source file's header the words "Sun designates this particular file as subject to the "Classpath" exception as provided by Sun in the LICENSE file that accompanied this code."
Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

That exception makes it explicit that the ClassPath libraries so marked can be linked with other applications without affecting the licensing of the application.

The JavaME edition has some additional libraries, specific to mobiles obviously, which do NOT offer this exception - they're GPL only. Hence why many users of JavaME chose to get a proprietary licence from Sun. Google do not use those APIs anyway, AFAIK. I.e. it does seem that there were no licensing obstacles to Google using the OpenJDK, at least in terms of wanting to avoid applications having to be GPLed (Google might have started its Dalvik work while Sun were still in the process of GPLing the JDK - anyone remember the exact timeline?).

Given that Google generally went out of its way to avoid having any GPL code in Android, it seems that their motivation was simply to avoid being restricted in any way by copyleft. I wonder if that choice was made on a rational basis, or out of less rational, base GPL hatred/fear.

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Classpath Exception not included in the mobile edition

Posted Aug 20, 2010 10:39 UTC (Fri) by nim-nim (subscriber, #34454) [Link]

Again, your argument is defeated by the fact that what Google finally produced is a lot closer to JavaSE than JavaME (Harmony is a JavaSE not ME clone)

JavaME was written for the kind of phones the iPhone and Android stormed over: clunky, limited hardware where the software was an afterthought because the phone industry worried more about ringtones and MMS than about the user experience

It takes more than a ME moniker to define what's needed on a smartphone.

Classpath Exception not included in the mobile edition

Posted Aug 26, 2010 12:42 UTC (Thu) by willjcroz (guest, #62784) [Link]

AFAICT the use of JavaSE/Harmony libraries is complicated by the field of use restrictions issued by Sun for the OpenJDK JCK compliance test framework (required to 'comply' and get patent license). It's use on anything other than a standard computer on a desk is prohibited from what I have read.

See the open letter to Sun from Apache Harmony team:

http://www.apache.org/jcp/sunopenletter.html

and its related FAQ:

http://www.apache.org/jcp/sunopenletterfaq.html

From what I can find, Apache Harmony project's concerns have not been addressed. Unless you know otherwise, in which case please post details of how Sun addressed this.

Classpath Exception not included in the mobile edition

Posted Aug 27, 2010 11:41 UTC (Fri) by mjw (subscriber, #16740) [Link]

> AFAICT the use of JavaSE/Harmony libraries is complicated by the field of use restrictions issued by Sun for the OpenJDK JCK compliance test framework (required to 'comply' and get patent license). It's use on anything other than a standard computer on a desk is prohibited from what I have read.

There are no such field of use restrictions in the OpenJDK JCK:
http://openjdk.java.net/legal/openjdk-tck-license.pdf
There are lots of other problems with it though, primarily that it is proprietary and you need to sign a NDA to not discuss the results...

> From what I can find, Apache Harmony project's concerns have not been addressed.

The problem with their concerns is that they are unverifiable because they did the "negotiations" in secrecy without involving the bigger libre java community. They probably really got a bad deal, but it is hard to help out if they keep the details hidden: http://gnu.wildebeest.org/blog/mjw/2007/04/21/openjck/

Classpath Exception not included in the mobile edition

Posted Aug 20, 2010 11:32 UTC (Fri) by mjw (subscriber, #16740) [Link]

> But again, JavaME is NOT covered by that exception. Thus the only way for Google to stay in the clear would have been to use the _full_ JavaSE, not a subset.

You seem to be confusing the "specification" with the "implementation" and what Android/Dalvik actually supports.

The full GPL implementation that Oracle/Sun distributes is called PhoneME: https://phoneme.dev.java.net/ https://phoneme.dev.java.net/source/browse/phoneme/legal/

The OpenJDK implementation under GPL (+ exception) that they distribute is an implementation of JavaSE.

Some of the specified libraries overlap (although there are some subtle differences in behaviour) but neither is a full subset or superset of the other.

An example of usage of both PhoneME, OpenJDK and GNU Classpath, JamVM or Cacao derived implementations on embedded devices is the Bug: http://community.buglabs.net/kgilmer/posts/45-BUG-OpenJDK

Another example that blurs the lines between SE and ME (and happily combines code from various free implementations, PhoneME, OpenJDK, GNU Classpath, Cacao, etc.) is MIDPath http://midpath.thenesis.org/bin/view/Main/

Android/Dalvik resembles the Java SE variant the most. It doesn't reall resemble any java variant directly. But it doesn't include anything in ME that is not in SE. It can be seen as a subset of the SE libraries, with specific Android libraries added. The implementation is designed to run well on small devices, but isn't JavaME like.

Classpath Exception not included in the mobile edition

Posted Aug 22, 2010 5:00 UTC (Sun) by paulj (subscriber, #341) [Link]

It doesn't matter. Google are NOT using JavaME - they're using a subset of SE. So the OpenJDK GPL+CE implementation is there for their taking and should be acceptable - modulo the fact that Google don't seem to like the GPL much.