CPM provides a number of service layer interfaces that are specifically designed for customization. A new custom implementation can be provided for any of the interfaces listed below. It is worth noting that default implementations are provided for these interfaces. Please read the Persistence Cookbook on how to provide an implementation for a service layer interface. The default implementations of these interfaces can be replaced with a new custom implementation by creating a new Guice module class and adding a corresponding entry in the MODULE table. Chapter 5 - Creating a Google Guice Module - in the Persistence Cookbook explains this in detail.