Sun Charles Nutter and Thomas Enebo, often called "the JRuby Guys," about two-and-a-half years ago so they could work full time on JRuby, an implementation of the Ruby programming language for the Java Virtual Machine. Some months later Sun hired Nick Sieger, another key JRuby developer.

All three will start work at Engine Yard next week. Nutter said they decided to leave Sun largely because of the uncertainty resulting from its acquisition by Oracle, a deal that's expected to close later this summer pending regulatory approvals.

"To be honest, we had no evidence that Oracle wouldn't support JRuby, but we also didn't have any evidence that they would," Nutter said by telephone Monday. "Two out of the three developers making this move have families; we want to make sure JRuby will get to the next level, and we had to make a decision," he said.

Oracle is a big user of Sun's Java technology and says it's one of the main reasons it bought the company, though it hasn't given specifics about its plans.

Getting hired by Sun and being given the chance to work full time on JRuby was "pretty much a dream come true," Nutter said. The team got to work independently as a "satellite project," but with Sun's engineering resources behind them, including access to its Glassfish, NetBeans and JVM software.