Hibernate 3 Core - Basic

General Design persistent classes

• Write code for getters, setters and constructor
• Identify correct implementation of equals() and hashcode()
• Describe the Primary Key mapping mechanism and needed syntax
  • Explain mapping done using <id> element and @id annotation and corresponding relational structure
  • Describe the following generator strategies : increment, identity, native, sequence.
• Name and explain the composite primary keys mapping strategies
  • Explain The <composite-id> element and corresponding annotation
  • Using an embedded composed primary key class

Write code that manipulates Configuration and SessionFactory objects

• Construct a Configuration object that initializes itself reading hibernate.properties, hibernate.cfg.xml
• Write a property-based and xml-based configuration file containing dialect and database connection information.
• Describe the semantics of the following methods : openSession(), close(), addClass()

Create persistent object model classes containing types

• Establish the difference between the lifecycle of an Entity and a Type
• Write mapping file or annotation code that maps an Embedded Component in a POJO
• Identify correct Value Type collection mapping using <set>, <list>, <bag> and <map>
• Describe how to map a Component collection
• Given a hibernate collection mapping (xml or annotations) validate a corresponding relational model

Entity Relationship Explain entities relationships and describe corresponding table structure

• Describe Foreign Key mapping including
  • simple reference <many-to-one>
  • simple collection <one-to-many>, identify the following supported collection types <list>, <set>, <map>, <bag>
  • bidirectional association and the meaning of the inverse attribute
  • association table <many-to-many> mapping
  • enhanced association Table, write code that use a composite-element to map an association table containing data
  • Describe how to make hibernate constrain Foreign Key in one-to-one relationships
• Predict hibernate behaviour concerning cascading
  • Identify the correct cascade attribute values and link them to the POJO lifecycle.
  • Given code, establish what changes will be propagated to the database
• Troubleshoot performance problems using fetching and lazy loading principles (lazy & fetch attributes values)

Inheritance For the following inheritance mapping strategies

• Table per subclass <joined-subclass/>
• Table per class hierarchy <discriminator/> <subclass/>
• Table per subclass with discriminator <discriminator/> <subclass/> <join/>
• Table per concrete class
• Table per concrete class with UNION <union-subclass>

Be able to

• Explain pros and cons, basic knowledge of the different strategies and their differences
  
• Identify corresponding database structure
  
• Write code that establish a polymorphic association
  

Lifecycle Be comfortable with hibernate lifecycle

• Identify entity States : persistent, transient, detached
• Describe State Transition API : clear(), close(), save(), saveOrUpdate(), persist(), evict(), merge(), contains(), delete() and update()
  • Given code, identify when flushing is done.
• Explain the Dirty Checking mechanism
  • describe and understand the basic principle
  • establish how hibernate handles basic type and collection dirty checking
• Explain the purpose of the StatelessSession class

Object retrieval and Query Given the following entity Fetching techniques

• Hibernate Query Language
  • Write queries with basic syntax (from, select, where), sorting, aggregate functions
  • Describe the Java object structure returned by queries such as
    • select user from User as user
    • select user, user.name from User as user
  • Write code using the Session API that creates and execute queries
  • Inject parameters values in where clauses : using Query.setXXX() methods
  • Externalize queries in mapping files
• Query by Criterias and Query by Example
  • Write code that executes a simple query (equivalent to select + where + sorting)
  • Describe the purpose of the following related APIs : createCriteria(), Restrictions, Projections, Order, Criterion, Example, Example.create()
• Native SQL query
  • Identify the 2 places where you define the SQL query string (hardcoded or externalized)
  • Describe how to retrieve an externalized query using the Session API

Transaction Basic knowledge of Transaction and related things

• Write java code that use the Transaction object
  • Start and End a transaction
  • Test whether a transaction is active
  • Rollback a transaction
  • Write proper try-catch structure
  • Identify Hibernate's implementations of the org.hibernate.Transaction interface
• Pessimistic Locking
  • Write code that pessimistic-locks an entity using the related APIs Session.get()
  • Identify the different LockModes
• Optimistic Locking
  • Declare optimistic locking in mapping files <version> and <timestamp> and Annotations.
  • Explain when a StaleObjectStateException can be thrown