The team behind RoboVM, an iOS compiler of tools for mobile Java applications, says that making its core product open source has not worked and that current and future versions will be proprietary.

The company, which was recently acquired by Xamarin, used to publish its core compiler under the GPL licence. However, users noticed that the latest published version on GitHub was 1.6, while the product itself is at 1.9.

A thread on the RoboVM discussion group recently asked where the 1.8 source code was, given that the License.txt file within the distribution stated that it is released under the terms of the GPL. It also states, in addition, that "Your use of the Core Software is free of charge."

These provisions are both absent from the License.txt for release 1.9.

Yesterday RoboVM's Mario Zechner responded, stating that the open source model was not working:

Over the past few months, we have seen competitors actively exploiting our good faith by using our open source code to compete with us directly in commercial products. On the flip side, we have received almost no meaningful contributions to our open source code ... in light of the low contributions and behavior of competitors, we decided to stop automatically releasing changes to the core of RoboVM as open source.

Given that 1.6, which is three months old, was the last to appear on GitHub, it seems possible that not changing the licence for version 1.8 was an oversight. However, Zechner says that the company "will push the sources of RoboVM version 1.8 to the public repositories this week". The company is also offering "every single external contributor" a free, lifetime licence – though there are only 17 of them.

There is some unhappiness in the community over the Xamarin acquisition, not least because of recent price increases. "While for the previous 299$ annual subscription you had Eclipse and Intellij tooling included, it is now 125x12 = 1500$ (for a single developer) for the same thing. All of this to match what Xamarin is doing with Visual Studio," says one user, raising the possibility of forking the GPL code to create an open-source competitor.

That said, the Xamarin story makes a compelling case for the advantages of a more proprietary approach. Xamarin co-founder Miguel de Icaza kicked off the open-source Mono project, which was later acquired by Novell but remained open source. Xamarin.iOS, on the other hand, formerly called MonoTouch, is only available under a commercial licence. Xamarin has been more successful than Mono ever was, and its software has evolved rapidly as a result.®