As predicted by vnunet.com, Sun Microsystems has officially opened up the source code for its Solaris 10 operating system.

The complete source code will be made available in the second quarter of this year. In a first step, the company has put the code for DTrace up on OpenSolaris.org. The system performance optimisation tool was unveiled last November as part of the Solaris 10 launch.

Sun chief executive Scott McNealy revealed during a conference call that the Solaris code will be made available under Sun's Common Development and Distribution Licence (CDDL). The licence was recently granted official open source status by the Open Source Initiative.

The licence lets users make adjustments to the application without having to disclose too many details about the services that they ultimately deploy.

"It allows you to contribute back or stand on the shoulders [of OpenSolaris] and create your own proprietary value on top of the OpenSolaris code base," said McNealy.

Sun hopes that developers will pick up the application and put it in devices ranging from gaming consoles to mobile phones and switching equipment.

By opening up the code, Sun aims to regain some of the ground it lost to Linux over the past years. To further increase the appeal of Solaris over Linux, the company promised to apply an arsenal of 1,670 patents to protect developers and users against patent infringement claims.

Offering indemnification is an important area where Sun can differentiate itself from Linux, which has come under fire for allegedly violating intellectual property owned by SCO.

Sun has previously purchased a licence from SCO, which covers users and developers. The company's patent portfolio also acts as a deterrent that can be used to file counterclaims if a party decides to go after Solaris.

"We have done something nobody in the open source community has done," said McNealy. "We are assigning our 1,670 operating system related patents to the CDDL licensees in a way that allows them to operate in a safe harbour environment of patents."