The open API debate burst into the GigaOM Structure conference this morning with a theme emerging that represents the paradox of today’s open systems.

It’s now more about the pragmatists’ view of connected systems, versus the advocates for federation and distributed power across a number of players that “shift the monopoly from the service providers to the platform,” as Rishidot Founder Krishnan Subramanian wrote in a blog post last year.

The players in the debate today at Structure included Marten Mickos, CEO of Eucalyptus, Chris Kemp, CEO of Nebula and Sameer Dholakia of Citrix.

All three of those on stage today have intertwined relationships. Kemp worked as the CTO at NASA and served as one of the founders of OpenStack. Eucalyptus and NASA had a relationship that fell through. NASA and Rackspace formed OpenStack, which was viewed as a refutal of Eucalyptus.

Eucalyptus retrenched and has since emerged as one of the stronger players in the market for developing extended data infrastructures for enterprise clients, providing full support for AWS APIs. Citrix initially joined OpenStack, then acquired Cloud.com and made it Cloudstack. Citrix has dropped much of its support for OpenStack. Earlier this year Citrix gave Cloudstack to the Apache Foundation and announced compatibility with AWS.

Mickos and Dholakia surely represented the pragmatists, saying it just makes business sense to support the AWS API. Kemp sat in the middle saying the long-term fight is for complete openness among service providers.

Eucaltyptus supports AWS due to its status as the predominant API, Mickos said. Hundreds of thousands of developers use AWS and therefore it means support is critical. Earlier this year.

Kemp said the future of cloud infrastructure will consist of modular innovative open projects and not monolithic monopolies. It will take time for this world to emerge but it will come.

Dholakia said Amazon has had great success and they’d be crazy not to have a compatability layer.

“The pragmatism of supporting customers is necessary,” Dholakia said.

Kemp chided both Mickos and Dholakia. He said Eucalyptus is an open implementation of a closed platform. He called AWS the Wal-Mart of infrastructure. He said Citrix prepared Cloudstack for the Apache Foundation in closed meetings.

The debate about openness is turning to the API. The people arguing with each other are all historically open-source advocates. The AWS API represents the interface. Data flows back and forth from AWS to apps that have its own APIs.

The OpenStack camp says what’s behind that AWS API is what matters. And no one knows, really, what is behind the curtains. AWS is a black box in that respect.

Proponents for AWS argue that the API allows for an ecosytem of open systems that communicate, pass data and provide the means for applications to run in and outside a corporate data center. Mickos has even said that AWS is playing the role of Linux distributions.

What’s this all about? It’s about openness in a different context. It’s not an argument about open source. It’s really more about what’s to come. If we do see a future of federated systems then service providers will have to integrate. The pragmatists will look at market share and community size to make their decisions. The federated camp will want power distributed, not in control of one provider. The pragmatists will not really care as long as their customers are happy.