Google App Engine is a powerful cloud-computing platform designed to help developers more easily create and manage scalable web applications. With the recent addition of Java support, developers can now interact with the Google App Engine datastore using JDO and JPA, both standard Java persistence APIs. In this talk we will discuss how these standards allow you to create a “soft schema” on top of a schema-less datastore, and the advantages this soft schema provides. We will also explore how the datastore’s “pre-sharded” transactional model is exposed in these standard interfaces. Finally, we will discuss how a soft schema maps to a traditional, relational schema, and examine some techniques for porting persistence code on and off App Engine.