Chapter 25 Managing Persistent Component State

Persistence for entity components

An entity component is an EJB entity bean or a component of another type that implements the CtsComponents::ObjectControl interface. Entity components present an object view of relational data to clients; each instance of an entity component maps to a row in a database relation.

Component implementation requirements

Entity components can be EJB entity Beans implemented according to the EJB 2.0, 1.1, or 1.0 standard (see Chapter 7, "Creating Enterprise JavaBeans Components"). You can also implement CORBA entity components by following these requirements:

Use CtsComponents::ObjectControl as the component's control interface. See "Configuring a control interface".
Define a primary key type for the component. See "Defining the primary key type" for more information.
Create a home interface for the component with a findByPrimaryKey method and, optionally, additional finder and create methods. See "Patterns for finder methods" for more information.

For an entity component, you can manage persistence using these techniques:

Component managed You implement the code that reads and writes persistent data and maps the relational column values to fields in the implementation class. This model corresponds to the Bean Managed Persistence (BMP) model defined by the EJB 2.0 and 1.1 specifications, but has been extended to support other component types.
Automatic persistence EAServer generates skeleton code to manage the storage and retrieval of persistent data. This model corresponds to the container-managed Persistence (CMP) model defined by the EJB 2.0 and 1.1 specifications, but has been extended to support other component types.
Generated class A generated C++ or Java class saves and restores component state from a remote database. EAServer (Jaguar Manager) does not generate such classes, but third-party tool vendors can use this option. The generated class can inherit from or delegate to the component's implementation class to save and restore component state.