Google App-Engine and Top-Down Cloud Computing

Many people are comparing Google's App Engine to Amazon S3. There's certainly some relation - both offer the ability to build an application and run it 'in the cloud' - in someone else's infrastructure, with seemingly limitless expansion room (well, Google's offer has a strict quota, but one assumes there'll be pay plans beyond that point in the future).

But Amazon's approach has been bottom-up - web services that allow you to control the bits and bobs of infrastructure you might use to create your own cloud-computing application (e.g. EC2 instances and S3 storage). This gives you a fair amount of flexibility while still being simpler and more cost-effective (in some cases, anyway) than building your own grid infrastructure. For instance, EC3 can allow you to scale to handle peak loads while still keeping your costs low when there's less traffic.

On the other hand, Google's top-down approach isn't really about giving you options, it's about creating a model for applications that run in the cloud and restricting you to that model, so that you can focus on building an application and trust that the limitations Google has placed on you will allow Google to scale it up and down as necessary to meet demand.

The former has a lot more control and sometimes that'll be very necessary for applications that are difficult to build in Google App Engine (for instance, there's only language support for Python at the moment). On the other hand, the latter offers a very simple model for creating applications at scale without needing to really know that much about how to scale an application.

It'll be interesting to see, with time, if development for the cloud is closer to Amazon's (full control, skill required) or Google's (restricted choice, with simplicity). I'd probably bet on the latter for most applications.

I'll have more to say on this later -- I'll be doing something more comprehensive for InfoQ.