Red Hat Certified Specialist in Persistence Exam (EX297)

You should be able to perform the following tasks:

Configure JPA/Hibernate

• Configure PersistenceUnit properties, including:
  • Location of configuration files
  • Java EE-specific configuration details
  • Java SE-specific configuration details
  • Hibernate-specific configuration details
• Connect to a PersistenceUnit from a Java SE application
• Connect to a PersistenceUnit from a Java EE application
• Override PersistenceUnit default property values

Map a single table or object

• Understand the behavior of the id generators, including how and when the value is generated
• Understand how to map a primary key, including:
  • Using generated keys
  • Mapping simple business keys
  • Mapping compound keys
• Understand object identity and business equivalence
• Configure database-specific information, such as table name, column name, column width, and column attributes (nullable, unique, type, and so on)
• Convert an existing Java object into a persistent object using JPA/Hibernate
• Map basic JPA data types to corresponding database types
• Given an existing database table, create a new persistent Java object to map that table
• Understand how and when to use lazy versus eager loading
• Understand and use optimal mapping strategies for collections and value types
• Handle Java/object model-specific properties and behaviors in a persistent object. This includes:
  • Serialization
  • Transient properties
  • Generated and calculated properties
  • Immutable properties
  • Value types
  • Co-dependent properties (i.e. where a property's valid values depend on the value of another property)

Map object relationships with JPA/Hibernate

• Understand how to map relationships, including but not limited to:
  • Value relationships (for example, has-a details object)
  • Parent/child relationships
  • One-to-one relationships (both unidirectional and bidirectional)
  • Many-to-one and one-to-many relationships (both unidirectional and bidirectional)
  • Many-to-many relationships (both unidirectional and bidirectional)
• Understand default mapping behaviors, including but not limited to:
  • Foreign key names
  • Association table names
• Understand the use of foreign keys and join tables when creating relationships
• Understand how to map a compound primary key based on the relationship
• Understand JPA/Hibernate collections (sets, maps lists, and bags) and how they map to object and table relationships
• Understand the performance impacts of the different collections
• Understand how and when to use lazy versus eager loading, including the performance and code impacts of both
• Given a set of existing tables and relationships, create a persistent Java object graph matching the database
• Map an existing object model, including various associations, to a persistence store
• Determine optimal loading strategies for a given business process

Map hierarchical object relationships with JPA/Hibernate

• Understand how to represent different object hierarchies using JPA/Hibernate
• Convert an existing Java object hierarchy to persistent objects using JPA/Hibernate
• Represent an existing set of table relationships as an object hierarchy (for example, savings account, credit card, and loan account)
• Understand polymorphic queries and associations
• Understand the benefits and limitations of the different inheritance strategies
• Analyze and determine optimal database representations for different object hierarchies

Understand transactional behavior (ACID)

• Acquire and use a transaction context under:
  • Java EE/CMT
  • Java EE/BMT
  • Java SE using JPA APIs
• Understand how the persistence context is bound to the transaction in Java EE
• Understand transactional context propagation with EJB3
• Understand the consequences of a transaction rollback at the persistence context level
• Understand transactional concurrency risks
• Evaluate data loss/corruption versus performance trade-offs

Retrieve persistent objects

• Understand JPA/Hiibernate loading strategies:
  • Lazy loading
  • Subselect loading
  • Batch loading
• Understand and use advanced query options:
  • HQL/JPA QL
  • Criteria APIs
  • Native queries (SQL)
• Use the runtime eager fetching feature
• Use named parameters
• Anticipate and avoid LazyInitializationException
• Analyze and improve JPA/Hibernate performance
• Understand and use JPA optimistic locking and Hibernate pessimistic locking extended features

Manipulating persistent objects

• Understand entity states, such as:
  • transient
  • persistent
  • attached
  • detached
  • removed
• Understand how to change the state of an entity/entity graph using JPA APIs
• Understand the lifecycle of the persistence context and its impact on the entities being managed
• Apply JPA/Hibernate batching features:
  • API usage patterns
  • DML queries
• Determine and apply optimal implementation and cascade settings to manipulate an object graph
• Evaluate when to use batching