We've heard a lot about public clouds, private clouds and hybrid clouds. In your book, you mention a fourth category: community clouds. What exactly is a community cloud and how does it differ from the other types?
Community clouds are less common, but they're still out there. Basically, it's very simple: A community cloud is a lot like a private cloud, in that it's a cloud environment that is collectively defined and owned and governed, not by a single organization but by a group of organizations that form a community.
For example, take a certain industry, like the financial sector. A group of banks might want to form a community cloud for collaboration or for the sharing of information or documents or other types of services. That group of banks would work together to build this environment and own it and evolve it, and they would share the responsibility for it. They might bring out outside help to do so, but it's all under their control.
Another example can be found in the public sector, where you have organizations that need to share data with other public-sector organizations. They have strict regulatory requirements that they need to adhere to regarding the processing of the data. They don't want to put that data into the public cloud.
Instead, they want to have ownership over how the information is defined and how it's used. And they don't want clutter. They want to know that only their group of organizations is using and accessing the data, as opposed to a public cloud environment, where you can have cloud consumer organizations from around the world sharing the underlying IT resources. In the community cloud environment, there are usually a lot of limitations as to who can share and control the cloud and those resources.
So to recap: A community cloud is basically just a private cloud for a specific group of organizations that use it and collectively govern it over time.
Thomas Erl is CEO of Arcitura Education Inc., an IT training/certification company, and co-author of Cloud Computing: Concepts, Technology & Architecture (Prentice Hall, 2013).
This was first published in September 2013