A huge amount of digital ink has been spilled trying to define "the cloud" and "cloud computing" and now Amazon Web Services has once again upped the ante with its latest Virtual Private Cloud (VPC) services.
The VPC,by fellow CNET blogger James Urquhart, provides a way for companies to create a logically separated set of Elastic Compute Cloud (EC2) instances and a secure VPN connection to their own networks. Effectively, it takes a chunk of Amazon's services and makes it private. Still on the Internet and still on shared hardware, but private.
The VPC use case is for enterprises to use cloud services outside their firewall, connected in a secure manner. This is very compelling to IT shops that need more resources but have to date been concerned about security. And while this approach can certainly be called a "private cloud," I believe the more likely private use case is that of an "enterprise cloud" that is behind the firewall and adheres to compute cloud principles (elasticity, seamless scaling, etc.).
Where the computational resources live seems to be the crux of the private vs. public cloud discussion, and now that Amazon has defined private clouds as part of an Internet-hosted infrastructure I expect we'll see more references to "enterprise clouds" as the software matures.
The enterprise cloud is really just an actualized version of the "compute cloud" concept that we've seen for the last 10 years (and I've written about repeatedly) with a deployment model that mirrors Internet-based cloud services.
A "compute cloud" is a different animal, according to the developers of Eucalyptus, an open-source, EC2-compatible infrastructure-as-a-service. Typically based on virtual machines, "cloud computing allows users to dynamically provision processing time and storage space from a ubiquitous 'cloud' of computational resources."
Incidentally, Amazon's new offering not only resets the semantics of how we talk about cloud computing but also puts serious pressure on other cloud providers to offer feature parity. Few other providers offer the full breadth of AWS services and those that do are constantly playing catch-up.
Another aspect of the new offering is the impact it has on a variety of start-ups that have attempted to do similar things, or to augment AWS in ways that Amazon hasn't yet tried. As with so many other platforms, the risk of building on top of something you don't own (i.e. EC2) is significant. And while AWS continues to be very innovative, start-ups are going to have to be very agile to outfox Amazon.
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