Like the rest of the financial trading world, the New York Stock Exchange (NYSE) is a high-stakes arena with a very low tolerance for latency and downtime. It operates in an environment where millionths of a second can mean a steep drop in a stockholder’s portfolio, so the cookie-cutter approach to the cloud won’t do.
While some cloud advocates say that downtime in the cloud is inevitable , the NYSE cannot and will not subscribe to that notion.
Most people have put the cloud into three neat categories: public clouds, which offer access to compute resources on a utility basis over the Internet; private clouds, which restrict the sharing of compute resources to an on-premises organization; and hybrid clouds, which leverage different aspects of public and private clouds for unique use cases.
But Chuck Hollis, chief technology officer at EMC Global Marketing, believes the community cloud model is a fourth option that other industries might want to consider, based on the NYSE’s success  with this approach.
Community clouds aren’t new; Red Hat cloud evangelist Gordon Haff was praising the model as the future in a CNET article  back in 2010. Some people consider community clouds a subset of private or hybrid clouds, but Hollis argues in a post on his blog  that the community cloud deserves recognition as its own distinct model of cloud computing, and that other industries should consider a community approach before going solo:
It's not a private cloud: community cloud services run multi-tenant on shared infrastructure using a common operational model. It's certainly not a public cloud in several important aspects.
Certain aspects might be described as hybrid, but that's not what's really going on here. So it certainly deserves a separate moniker as it's meaningfully different than other forms of cloud.
Like the private cloud, the NYSE’s VMware and EMC-powered community cloud places a high priority on security measures. But like the public cloud, the community model takes advantage of shared infrastructure to reduce costs for individual organizations that are part of the community cloud. Unlike the hybrid cloud, it goes beyond using a shared IT environment for development testing or spikes.
Using the community cloud approach, the NYSE offers various “as a service” solutions to other organizations in the financial trading business, granting them the speed and flexibility of the cloud, without the cost of investing in a private cloud infrastructure or sacrificing on security.
This vertical-specific community approach is important because no one understands the unique needs and challenges of the financial trading community better than other trading organizations, Hollis argues.
What characteristics make the environment ripe for a community cloud? Hollis outlines a few signs worth paying attention to:
Energy companies and big retailers could similarly organize their IT resources, which could see the community model rise above the hybrid approach.
If the community cloud continues to distinguish itself as an enterprise cloud-computing solution, the Three Musketeers of cloud computing (private, public and hybrid) might have to make room for a fourth member of the crew.