Under the GPL, any derivatives of GPL code and code combined with it must be distributed under the liberal GPL license. Acknowledging ISV concerns, Sun is allowing use of the "ClassPath exception" to the GPL, which enables combination of proprietary code with GPL ClassPath libraries without the need to redistribute the proprietary code.

Java out-ships Solaris, GNU Linux, the Macintosh, Symbian, and Tivo combined, Schwartz said. "We're talking about billions and billions of users."

IBM, although applauding the move to go open source, released a statement objecting to Sun's strategy. Attributing its statement to Rod Smith, vice president of Emerging Internet Technologies in the IBM Software Group, the company advised an Apache path for Java.

"IBM supports all the OSI approved open source licenses. Having said that, there already is an important existing open source effort working with Sun to create a Java-compatible implementation of Java SE (Standard Edition) in the Apache Foundation -- namely the Harmony project. In addition, there have been some very recent announcements that companies active in the Java ME (Micro Edition) space will be contributing key Java technologies to the Apache Foundation to jumpstart Java ME projects," Smith said.

"In light of the Apache projects, we have discussed with Sun our strong belief that Sun should contribute their Java technologies to Apache rather than starting another open source Java project, or at least make their contributions available under an ‘Apache-friendly' license to ensure the open source Java community isn't fragmented and disenfranchised, instead Sun would be bringing the same benefits of OS Java to this significant and growing open source community."