It's not every day your boss puts you on the spot, but that's exactly what the head of Sun Microsystems did to his chief software executive as they both celebrated the vendor's move to make its core Java platform freely available.

Sun confirmed Monday that it's open-sourcing both its Java Platform Standard Edition (Java SE) and its Java Platform Micro Edition (Java ME) under the GNU general public license version 2 (GPLv2). GPLv2 is a popular license already used by free and open-source software (FOSS) projects and products including the Linux operating system. It's the first time Sun, which has committed to open-source all its software, has adopted a license other than its own CDDL (Common Development and Distribution License).

All of which poses an obvious question: Will Sun look to use the GPL for other offerings it's already open-sourced such as the OpenSolaris version of its operating system? And so to the interchange between Jonathan Schwartz, Sun's president and chief executive officer, and Rich Green, the company's senior vice president of software at an event to formally open source Java in Santa Clara, California, which was also webcast:

"Are you adverse to changing the license, Rich Green?" Schwartz asked.

"Certainly not," Green responded, prompting the Sun CEO to fire back in a half-joking manner: "Will you GPL Solaris, Mr. Green?"

"We will take a close look at it," Green said, adding that it was possible that the familiarity and comfort level many developers have with the GPL may result in Sun adopting it for OpenSolaris.

Both men positioned Sun's embracing of GPL for Java as an important change in the software landscape, which the company hopes will result in much greater adoption of all flavors of Java across mobile devices and computers.

Over the decade Java's been in existence, 4 billion devices have used the technology, according to Schwartz, with the Java platform shipping on eight of every 10 phones today. "How do we get to the next 4 billion?" he asked. "How do we continue to create opportunity in the marketplace?"

Monday's announcement 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 said.

He showed video clips of leading FOSS luminaries welcoming Sun's move including Richard Stallman, the creator of the GPL. Stallman said that Sun has now contributed more software than any other company to the free software community. "It shows leadership," he added. "It's an example I hope others will follow."

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.

As an aside, Sun also announced it will open-source the long-time Java mascot Duke, a black-and-white triangle with a red nose and black arms, so any developer can freely use the image.