One, and only one, open source project usually gains the upper hand in a new software category, but cloud has three tough contenders in OpenStack, CloudStack, and Eucalyptus. Must one win?

The role of open source firms has been to consolidate a set of rapidly occurring changes in a class of commercial software, frequently adding their own updates to the code and then commoditizing them in the marketplace. The Apache Web server did that. The JBoss Application Server under Marc Fleury's team of developers did it.

But in cloud software, the opposite is happening. There are no leading commercial products, but there are four open source projects. The commercial products are not advertising the capabilities of a new class of software; the open source projects are. And while one, and only one, open source project tends to gain the upper hand in each new category, there are three contenders in the cloud space, with none of them having a clear advantage.

The stage had been set with heightened tension between the three as Citrix announced in April that CloudStack would become an Apache project. Citrix had been a contributor to the OpenStack project. But Dholakia explained in an interview that Citrix bought Cloud.com "because we needed to be in the market sooner than OpenStack would allow to compete with VMware."