[FIGURE (note 7-1 and 6-1 are the same (Business web hosting)
[FIGURE (note 7-1 and 6-1 are the same figure) ] Figure 6-1 Class Diagram of Customer and Address EJBs Abstract persistence schema The CMP 2.0 entity bean classes are defined using abstract accessor methods that represent virtual persistent and relationship fields. As already mentioned, the actual fields themselves are not declared in the entity classes. Instead, the characteristics of these fields are described in detail in the XML deployment descriptor used by the entity bean. The abstract persistence schema is the set of XML elements in the deployment descriptor that describe the relationship fields and the persistent fields. Together with the abstract programming model (the abstract accessor methods) and some help from the deployer, the container tool will have enough information to map the entity and its relationships with other entity beans in the database. Container Tools & Persistence One of the responsibilities of the vendor s container deployment tool is generating concrete implementations of the abstract entity beans. The concrete classes generated by the container tool are called persistent classes. Instances of the persistent classes will be responsible for working with the container to read and write data between the entity bean and the database at run time. Once the persistent classes are generated, they can be deployed into the EJB container. The container informs the persistent instances (instances of persistent Copyright (c) 2001 O’Reilly & Associates 4
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