This chapter discusses the architecture of the core Cayenne framework. It only deals with the runtime operation of the object-relational persistence layer. Mapping procedures and remote object persistence are discussed elsewhere. The information below is not strictly required to start using Cayenne, so new users can skip it initially and come back later to gain better understanding of how Cayenne operates under the hood.

### Sections

1. Contract between Persistent Objects and Cayenne
2. Persistent Object Lifecycle
3. Runtime Components
4. Transactions
5. Primary Key Generation Strategies
6. Object Caching Mechanism