The most prominent is Microsoft. While the software giant is quick to explain that it likes the active engagement with programmers, the company considers the GPL unacceptable, said Martin Taylor, general manager of Microsoft's platform strategy.
"There are restrictions in the GPL today that prevent us from doing anything with it," Taylor said. Microsoft prefers licences that permit software to be used in proprietary projects as well.
Sun is another critic. In a dual-pronged competition, Sun has begun vying both with Linux and with the GPL by releasing its own version of Unix, Solaris, as open source software under the Community Development and Distribution License.
The CDDL, like the GPL, lets anyone change software but requires that those changes be publicly released. Unlike the GPL, though, the CDDL permits a tight coupling between its open source components and other proprietary components.
"If people want to use the GPL and integrate with it, they have to adopt the proprietary licence called the GPL," said Sun president Jonathan Schwartz in an interview this month. "Basically it forces your hand. You don't have any choice anymore."
Version 3 of the GPL, when it does arrive, won't necessarily apply to Linux, however. Linux leader Linus Torvalds specifically chose version 2 of the GPL to govern Linux -- but omitted a provision that would permit using a later version of the licence.
Stallman recommends against that approach, in part to permit software governed by one GPL to be used in future GPL projects. "That's too bad. That's his problem," Stallman recently said of Torvalds' choice.
Among the reasons for an update is clarifying how close GPL and non-GPL code may come before a GPL provision requires the other package also be governed by the GPL.
For some years, that debate has been defined by whether one software component is linked through fixed "static" links or more spur-of-the-moment "dynamic" links. That discussion already is obsolete because of how different modules of software now interact on the Internet through Web services technologies such as SOAP, or Simple Object Access Protocol, Moglen said.
"Static and dynamic linking is no longer the fight we need to have. Instead we have to ask ourselves about SOAP and bubbles and nets and stuff moving around in grids and through intersections and heaven only knows what else," Moglen said.
Another complication will be making sure the GPL works in the dozens of countries where GPL software now is being used. And the voice of corporate powers who were absent in 1991 must be heard.
HP is one of those voices. But Martin Fink, vice-president of Linux at HP, is a big GPL fan. Even so, the licence needs to be updated for modern computing issues, he said.
"I agree with Eben's view that a year out from a first draft is reasonable," Fink said. "I'm not sitting here in a panic waiting for GPL version 3, but it's not something we can let go forever."
