Scalebility and n-tier architecture on GAE

[Robert Åkerblom-Andersson]

Hi, I am designing the architecture for an enterprise application that should be designed to be able to handle a big number of users and for big traffic loads and therefor I have been doing some research on scalability and n-tier architectures. I found this blog post to have many good points and a good summarize of the info I have found:

The ten basic rules of enterprise systems design (source: galratner.com)

Although this list of rules seams good they might need some adjustments since this are meant for a "traditional hosting". So I have some questions related to the link above and how the concepts best should be applied to GAE:

1. The blog posts talks about building the application so that it can be run on different servers, different layers should be able to run on different server/serverfarm and then they should communicate via the network. How does that best apply to GAE? Just use different serverlets and/or backend processes and they will automatically spread out in a good way?

2. In a N-tired architecture, wikipedia says that different layers should be able to talk to each other over a network so that the system can scale out, what is the best way to communicate "over the network" inside an GAE application in such a way that it should scale good?