Some notes on free Java

The free software community would appear to have developed a winning strategy for bringing semi-proprietary code under a free license. Just create a project to reimplement that code, and name the project "Harmony." About the time that the Harmony project starts to make some real progress, the original code base will be relicensed to the GPL, and everybody will be happy.

This approach worked well with the first Harmony project, which was created to make a free version of the then-proprietary Qt library. In September, 2000, Trolltech finally made Qt available under the GPL. More recently, a Project Harmony set out to create a free Java implementation. A year and a half later, Sun Microsystems finally let go, and has promised to release Java as free software - and under the GPL at that.

Clearly some serious thought needs to be put into picking an appropriate target for the next Harmony project.

Actually, the "Harmony" name may not become available for a while yet; a quick look at the mailing list shows that, unlike the previous Harmony project, the current Harmony developers are continuing full-speed with their work. One might well wonder why, given that the "real" Java code is now promised to the community. It may be partly a matter of momentum, and partly waiting until the code actually becomes available (it will be a few months yet). Sun's interesting choice of the GPL also appears to be relevant. The Harmony project, being under the Apache umbrella, is using the Apache license, which is not compatible with the GPL. So the Harmony developers will not be able to make use of Sun's code in their project. If they want an Apache-licensed Java, they will have to continue to work to create it themselves.

There appears to be some concern within Harmony that Sun will require copyright assignments from those who would contribute to the GPL code base, and that, in turn, would allow Sun to make use of contributed code in proprietary projects. There are Harmony developers who are unwilling to contribute under those conditions. It has also been suggested in the Harmony camp that Sun might use patents to enforce Java compatibility. So Harmony may well continue for a while.

Another project which will be affected by this release is GNU Classpath. Unlike Harmony, however, Classpath uses a "GPL plus exception" license which allows the use of the library in proprietary applications. Sun's choice of the GPL makes life easy for the Classpath developers - especially since Sun adopted the same exception. But it does leave open the question of whether Classpath is needed at all. The real answer there probably depends on the shape of the actual code release; there may be parts of the "real" Java class library which Sun is unable to release, and which might then be substituted from Classpath. It also seems that Classpath has managed to build a dynamic and effective development community; the desire to continue to develop in that environment may keep Classpath going for a while yet.

Many pixels have been expended in attempts to analyze Sun's choice of the GPL. Most likely, Sun went with the GPL because (1) the response to the CDDL has been lukewarm at best, and (2) experience shows that GPL-licensed code is relatively resistant to the creation of incompatible forks. Sun's ostensible reason for resisting free licensing all these years was a fear of incompatible versions, so fork resistance should have been on their minds. Also worthy of note is the fact that Sun has specified that it is using version 2 of the GPL. A switch to GPLv3 seems likely once the license is final (see Jonathan Schwartz's weblog), but Sun is not committing to that ahead of time.

Sun has made some hints that Solaris might move over to the GPL as well. This would be a significant change, as it would allow Solaris code to find its way into the Linux kernel. There must be useful code within Solaris, even if some of the more interesting parts (the ZFS filesystem, say) would be a major challenge to port.

In any case, Sun's freeing of Java is a significant - if a bit overdue - gift to the community. It will enable the Java language to become a first-class citizen within Linux distributions and make a powerful language fully available to free software developers. Sun certainly cannot be faulted for failing to contribute in recent years. Soon, it will be up to the community to take this code and do great things with it.

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