Open source picks some new fights

"It's not a matter of whether something does or doesn't exist in open source," Taylor says. "The question is the level of integration across the stack, up and down, and the amount of work to tune and build on top."

But software that's good enough is finding a home within businesses. And there's likely room for both proprietary and open-source approaches within the same company. Henry Peyret, an analyst at Forrester Research, says that open-source middleware projects typically focus on the low end of the market, rather than pursue the most advanced features, as commercial companies do. As such, open-source products do not always compete directly with established products, he says.

"Some customers recognise that they prefer some good-enough products, even if it does not have all the features," Peyret says. "If they want to have these specific features, they prefer to put in commercial products for that niche, not the overall enterprise."

Going with open-source middleware products does require willingness to accept risk and some in-house technical skills, Manes noted. Open-source projects could conceivably fizzle out, and the reliability of commercial support is not always clear.

"There is a cultural issue as to whether a given company is willing to invest the amount of effort in support and take the risk of using this open-source technology versus going with IBM," she says.