At the same time, Structure 2012 featured a series of workshops, including one Wednesday taught by Roman Alekseenkov, a director of engineering at consulting firm Mirantis. He showed how an open source utility, CrowBar, can quickly install a pre-configured version of OpenStack across any number of servers. CrowBar is open source code produced by a team at OpenStack community member Dell.

Kemp said similar contributions will be pouring in over the coming year from other vendors with integration expertise such as Red Hat, HP, and IBM.

But Mickos returned to the developer issue from his own point of view. As the former CEO of the open source database firm MySQL, he learned the power of being where the developers were, as MySQL was included in major Linux distributions, causing its popularity to mushroom.

Kemp countered that one of the most popular Linux distributions, Canonical's Ubuntu, had tossed out Eucalyptus code and substituted OpenStack's, but Mickos wasn't to be deflected from his point. "Millions of developers are working on Amazon. I listen to young developers. I barely understand what they're saying, but I listen. I would much rather be in the Amazon cloud where the developers are," he said.

Dholakia said CloudStack could make a similar case for itself. It powers the cloud services being offered by Korea Telecom, and is being adopted by British Telecom, KDI in France, and other telecom companies to power their cloud services. Telecom developers will enrich the CloudStack ecosystem, he predicted.

Despite areas of disagreement, the three panelists agreed that open source software was leading the field in cloud innovation and should strive to continue to do so. If they falter, VMware may prove as successful in establishing itself as a primary cloud software vendor as it has as a virtualization vendor, warned Dholakia.

"VMware has built its approach to the cloud on the last generation of hardware and software," responded Kemp. "I think the cloud is different. I think it needs to be built on the next generation," he said.

Added Mickos, "Why don't we all do that?"

The panel's time was up. "Can't we just have a hug?" called a member of the audience to the pugilistic panelists.

The three men stood up somewhat uncertain. Mickos and Dholakia reached out toward each other, across Kemp, who wasn't inclined to join in. They ended up caging him as they clasped each other on the shoulders. Avoiding lock-in, Kemp extended his arms, palms together, straight ahead and emerged from the hug like the prow of a ship, cresting a wave. The audience applauded. The panelists acknowledged the applause and exited.

Each of the debaters seemed to frequently lose sight of their primary competition---VMware in Citrix's case; Amazon and VMware in OpenStack's, and proprietary cloud package vendors in CloudStack's--in order to score points against each other. Only at the very conclusion was there a hint that all three might play a role in building out future public and private clouds.

At the same time, the Structure audience continued to remark on the unfettered nature of the exchange after the session was over. "That was good," said one exiting attendee, citing the understanding he had gained of the different natures of the projects. Open source code may or may not play a long term leadership role in the cloud, but the audience was convinced it had just seen three spokesmen who were determined to keep it at the forefront.

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