Open source is the future, but the general public licence (GPL) is not the best way to get there, Sun's chief operating officer Jonathan Schwartz told the opening keynote of the Open Source Business Conference in San Francisco.

Sun was criticised last January when it opened the source code of its Solaris 10 operating system under the Common Development and Distribution License (CDDL) instead of the more common General Public License (GPL).

In his most elaborate response yet to the criticism Schwartz said the GPL is unfair and "predatory". The GPL requires developers to publish all the code that they mix in with the original GPL code, where the CDDL allows them to guard their work if they want to.

"Imagine a developing nation that elects to use free software in the construction of its intellectual property and then finds that is has a rather predatory obligation to give back all the intellectual property to the wealthiest nation in the world that happens to be the author of the GPL," Schwartz noted.

The GPL is wrongly used as a way force developers to share their work because the creators have a hidden agenda of forcing a social model on the world, the Sun executive claimed.

He described the authors of the GPL as "individuals and companies that want to use intellectual property models to define social models and economic models rather than intellectual property models."

The controversy over the GLP has led to the Open Source Initiative (OSI)to reform the system for using open source code under licence. The latest version of the license, version 2, was released in 1991.