Google App Engine (GAE) is Google's offering in terms of a robust PaaS infrastructure. GAE enables the deployment of web applications, which scale when traffic increases or when more storage space is needed.
Several programming languages can be used, in particular Java and Python. The distributed nature of the GAE implies using a non-relational storage space, named the Datastore. Designing business rules should thus be adapted accordingly.
Recall that the GAE is one of the three Google Apps services that can take advantage of the Secure Data Connector to access enterprise data.
For more detail on GAE, refer to Chapter 6, Extending the Platform.