Roy Fielding, chief scientist at Day Software and co-founder of the original Apache Web server project, is the kind of guy who oozes cred in the open source community. He was lead architect on the HTTP specification and described Representational State Transfer--we know it simply as REST today--as a development method in his doctoral dissertation eight years ago.

When Fielding joined the OpenSolaris community advisory board in 2005, Sun Microsystems hailed his presence as a sign of its commitment to open source. The honeymoon ended in February, when Fielding resigned. Sun's pledge to give the community authority over OpenSolaris was "a sham," Fielding wrote in his letter of resignation.

"They were telling me they wanted a community, like the one around Apache," Fielding says in an interview. At the same time, "they were undermining the OpenSolaris brand," by distributing open source code combined with Sun proprietary code. "There's no point sitting around giving advice when Sun's marketing department will decide what it wants to distribute anyway," he says.

The discord underscores what can go wrong when big IT vendors get integrally involved in open source projects or, as has been increasingly the case, buy open source companies. Business technology organizations have years of experience watching their key software startups get snapped up and, in some cases, mutilated, but the large-scale commercialization of open source brings a whole new set of challenges.

The timing of Fielding's departure couldn't have been worse for Sun, which was completing a $1 billion acquisition of MySQL AB, developer of the MySQL open source database. What should businesses using MySQL expect will change under Sun ownership?

Nothing changes, asserts Sun CEO Jonathan Schwartz, who by leading the acquisition of MySQL and making the Solaris operating system and Sun's Java middleware suite open source has bet his job on the idea of a profitable coexistence between open source and proprietary software in the same company. Schwartz says he doesn't expect former MySQL CEO Marten Mickos and others from MySQL to become obedient Sun employees. What he really wants is for them to continue cultivating their communities of open source developers and users.

If they do, Sun will tap into the thousands of new open source users who download MySQL each week; it'll supply technical support to those who have built a major business around it; and it will have the chance to sell servers and offer its library of open source Java middleware and tools to the same prospects. Rivals such as IBM, Microsoft, and Oracle already have a broad front of software products in these markets, and embracing open source could give Sun an opening to be a disruptive force, capitalizing on its technical expertise while outflanking established players for new customers. So far, so good at least on one critical front--Sun hasn't lost any of MySQL's top leaders since it completed the acquisition in February.