Google Cloud Platform for Developers

Structure of a Google App Engine application

App Engine resources are structured as a hierarchy of services, versions, and instances, collectively referred to as an application. As we'll see, this hierarchy plays an important role in how systems are designed in App Engine, and relates closely to many of App Engine's features such as routing and deployment strategies. Note the following diagram:

App Engine uses a hierarchical model of services, versions, and instances

The hierarchical model of App Engine is as follows:

• At the highest level, the service (formerly known as the module) represents an individual web service such as an API or front-end ...