Sun Microsystems claims to have made Java more open-source friendly, while applying the brakes before fully going down the open-source path. Speaking at the JavaOne conference, the company said that its latest update, the Java Enterprise Edition 5 release (Java EE 5), supported a number of web services standards and has been designed to be easier to use than its predecessor, Java 2 Enterprise Edition.

However, Sun remains tentative on the open-source front. Over the years, the company has open sourced many Java components, but has stopped short of opening up the core Java specifications. Sun worries that such a move could threaten Java's "write once, run anywhere" promise by allowing another company to promote an incompatible version of Java.

During JavaOne's opening keynote address, Sun Software executive vice president Rich Green promised attendees that an open-source Java is on the way, but that Sun still has some concerns.

"There are two battling forces here," said Green, a long-time Java executive who returned to the company just weeks ago. "There is the desire to completely open this up … the flip side is, compatibility really matters. I don't think anybody wants to see a diverging Java platform."

"The challenge going forward is how to solve for both of those things," he added. "It's not a question of whether, it's a question of how, and so we'll go do this."

In the interest of improving relations with the open-source community, Sun also unveiled a new software licence, the Operating System Distributor's License for Java. The licence does away with restrictions that had made it difficult for Linux vendors to ship two critical Java components: the Java Runtime Environment and Java Development Kit.

One Linux distributor joined Sun executives onstage to express support for this new licence. "Because of substantial changes that your team has made, we can make Linux available directly to users of free software desktops," said Mark Shuttleworth, founder and chief executive officer of Ubuntu Linux distributors Canonical.

Though Sun is clearly interested in promoting Java on the Linux platform, the most prominent Linux distribution, Red Hat, was noticeably absent from a two-hour keynote presentation that also featured speakers from Microsoft and open-source vendor JBoss.

Red Hat is the most popular Linux distribution for enterprise servers, the area where Java has had the most success. In fact, Canonical does not yet ship a server version of Ubuntu, according to Shellworth. That software is under development and is expected to ship on June 1.

While Sun executives have estimated that it will be perhaps a year and a half before the company is finally ready to open-source the core Java platform, developers have been offered a number of goodies. They include open-source versions of the following products, many of which are planned, but not yet available:

- Java Studio Creator, Sun's integrated development environment for Java.

- Java System Portal Server 7, software for developing web-based community portals.

- A Business Process Execution Language (BPEL) Engine from Sun's Java Composite Application Platform Suite (Java CAPS), which Sun acquired as part of its 2005 acquisition of SeeBeyond.

- Web services technology called Web Services Interoperability Technology (WSIT). Formerly code-named Tango, this software is designed to help Java software work with Microsoft's .Net.