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User Guide
The information contained in this section applies to IBM WebSphere Commerce Version 7.0.0.9 and Feautre Pack 8. The documentation also applies to all subsequent releases and modifications until otherwise indicated in new editions.
Developing
The topics in the Developing section describe tasks performed by an application developer.
Persistent object model
WebSphere Commerce deals with a large amount of persistent data. There are numerous tables defined in the current database schema. Even with this extensive schema, however, you might need to extend or customize the database schema for your particular business needs.
WebSphere Commerce enterprise beans
The persistence layer within the WebSphere Commerce architecture is implemented according to the EJB component architecture. The EJB architecture defines two types of enterprise beans: entity beans and session beans. Entity beans are further divided into container-managed persistence (CMP) beans and bean-managed persistence (BMP) beans.
Primary keys
A primary key is a unique key that is part of the definition of a table. It can be used to distinguish one record from others. All records must have a primary key. When you create a new record in a table, you may need to generate a unique primary key for the record.

Primary keys

A primary key is a unique key that is part of the definition of a table. It can be used to distinguish one record from others. All records must have a primary key. When you create a new record in a table, you may need to generate a unique primary key for the record.

In the WebSphere Commerce programming model, the persistence layer includes entity beans that interact with the database. As such, database records may be created when an entity bean is instantiated. Therefore, the ejbCreate method for the instantiation of an entity bean may need to include logic to generate a primary key for new records.

When an application requires information from the database, it indirectly uses the entity beans by instantiating the bean's corresponding access bean and then getting or setting various fields. An access bean is instantiated for a particular record in a database (for example, for a particular user profile) and it uses the primary key to select the correct information from the database.