container-managed-persistence

How do you avoid writing repetitive JDBC/database code for every entity bean?

With container-managed persistence (CMP), the EJB container automatically handles all database operations. The developer writes no JDBC code—the container generates SQL statements for create, read, update, and delete operations.

• Developer strips entity bean of any persistence logic
• Developer uses vendor tools to define O/R mappings (how bean fields map to database columns)
• At deployment time, container generates the data access code
• Container automatically performs INSERT, UPDATE, DELETE, and SELECT operations
• Mapping can be done at deployment time, making beans storage-independent

• Container handles all persistence automatically
• No JDBC code in the bean
• O/R mapping defined at deployment time
• Storage-independent—can switch databases without changing bean code
• Reduces bean size significantly

• Built from: Entity Bean, EJB Container
• Builds into: ejbCreate(), ejbRemove(), ejbLoad(), ejbStore(), CMP Abstract Accessors, CMP Lifecycle
• Contrasts with: Bean-Managed Persistence
• Related: Object-Relational Mapping, EJB-QL, CDATA Hack, One-to-One Relationship, One-to-Many Relationship, Many-to-Many Relationship, Bidirectional vs Unidirectional

• Less control over exact SQL generated
• Vendor-specific tools may be required for mapping
• May not support all database features