Sun is considering shifting its Solaris operating system to the more popular open-source GNU public licence (GPL) following its decision yesterday to put the Java platform under GPL rather than Sun's own CDDL licence.

At the launch of open-source Java, the company CEO Jonathan Schwartz asked his head of software Rich Green whether the company would consider changing OpenSolaris' licence. "We will take a close look at it," Green said, adding that it was possible that the familiarity and comfort developers have with the GPL may result in Sun adopting it for OpenSolaris.

Both men had stressed that Sun using GPL for Java was an important change in the software market, and something the company hopes will result in greater adoption of all flavours of Java across mobile devices and computers.

Over Java's 10-year lifetime, it has been used by four billion devices, Schwartz said, and is included in eight of every 10 phones. "How do we get to the next 4 billion?" he asked. "How do we continue to create opportunity in the marketplace?" The decision to open source Java makes Sun the single largest contributor to the open-source community, with Java SE alone consisting of more than 6 million lines of code, Green added.

The launch also saw a number of open-source advocates praising the decision. Creator of the GPL, Richard Stallman said of the decision: "It shows leadership. It's an example I hope others will follow."

But the real challenge for Sun as it continues on its open-source path is a cultural one, Green said. "How do we operate in full transparent view, managing the source code in full public view?" he asked. The membrane between Sun and developers outside the company has to be porous, Schwartz added, so that there can be a continual flow of feedback on the Java open-source work.

Original reporting by IDG News Service