1	Hibernate Frameworks for Data Access and SOA Jeff Zhuk Nick Samoylov David Lovejoy
2	Data Access – Old Style
3	Struts – Spring - Hibernate
4	Hibernate Uses OO query language called HQL Uses objects instead of tables and fields instead of columns Provides object-to-relational mapping for most DBs Separates data layer from business logics Uses DB connection info to retrieve DB schema Generates DAO beans with data fields mapping table columns Generates Insert/Update/Delete/Select statements for DB tables
5	Hibernate Synchronizer
6	Spring’s Map to Hibernate
7	Spring Maps Data Source Dialect and Provides Transaction Management for Hibernate Operations
8	Spring and Hibernate Reduce Business Code
9	Hibernate class – table mapping /** * @hibernate.class table="GT_NOTES" */ public class NoteImpl implements Note { …. }
10	Hibernate “sees” private constructor /** * Constructor needed for hibernate. / private NoteImpl() { super(); } /* * Constructor used to construct a note. */ public NoteImpl(String theNote) { this.note = theNote; }
11	Sequence based property /** * @hibernate.id column="NOTE_ID" generator-class="sequence" * @hibernate.generator-param name="sequence" value="GT_NOTES_NOTE_ID_S" */ public Integer getId() { return id; } private void setId(Integer id) { this.id = id; }
12	Object relations mapping /** * @hibernate.many-to-one * class="com.its.ebiz.ddm.model.RecipientImpl" * column="RECIPIENT_ID" not-null="true" */ public Recipient getRecipient() { return this.recipient; } public void setRecipient (Recipient recipient) { this.recipient = recipient; }
13	Any other convenience methods public String getRecipientName() { return this.recipient == (null? ”” : this.recipient.getName()); } public void setWhatever(Whatever w) { return this.whatever = w; }
14	Spring integration <!-- Hibernate SessionFactory --> <bean id="sessionFactory"class="org.springframework.orm.hibernate.LocalSessionFactoryBean"> … <property name="mappingResources"> <list> <value>com/jeppesen/ebiz/ddm/model/NoteImpl.hbm.xml</value> <value>com/jeppesen/ebiz/ddm/model/PkgImpl.hbm.xml</value> </list> … </bean>
15	Hibernate object mapping <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE hibernate-mapping> - <hibernate-mapping default-cascade="none" default-access="property" auto-import="true"> - <class name="com.its.ebiz.ddm.model.NoteImpl" table="GT_NOTES" mutable="true" polymorphism="implicit" dynamic-update="false" dynamic-insert="false" batch-size="1" select-before-update="false" optimistic-lock="version"> - <id name="id" column="NOTE_ID" type="java.lang.Integer" unsaved-value="null"> - <generator class="sequence"> <param name="sequence">GT_NOTES_NOTE_ID_S</param> </generator> </id> <many-to-one name="recipient" class="com.its.ebiz.ddm.model.RecipientImpl" cascade="none" outer-join="auto" update="true" insert="true" column="RECIPIENT_ID" not-null="true" unique="false" /> </class> </hibernate-mapping>
16	Transaction support <!-- Transactional proxy for the Recipient primary business object --> <bean id="domain" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"> <property name="transactionAttributes"> <props> <prop key="delete">PROPAGATION_REQUIRED</prop> <prop key="find">PROPAGATION_REQUIRED,readOnly</prop> </props> </property> </bean>
17	Application context ApplicationContext context = new ClassPathXmlApplicationContext ( "applicationContext-test.xml"); Façade f = context.getBean(“facadeFactory”); Whatever w = f.findWhatever(); Note n = new NoteImpl(“The note”); f.store(n);
18	web.xml <context-param> <param-name> contextConfigLocation </param-name> <param-value> /WEB-INF/applicationContext.xml </param-value> </context-param>
19	Hibernate with JTA for SOA Concepts Persistance as a Framework for Services Let's Consider RDBMS: Relational Database Management Systems (RDBMs) Often the platform of choice to persist application data Mature, stable, portable Multi user capabilities Security Robustness Transactional (data integrity) Maintain referential integrity COTS/OSS Utilities and Tools for reporting and maintenance
20	Hibernate with JTA for SOA Concepts (cont.) Object Oriented Programming Languages (OOPLs) Often the choice for implementing SOA’s. Rich libraries available for web and message based service processing All the benefits of an object oriented approach Inheritance Re-use, reduces duplication of code Encapsulation Security, abstraction Polymorphism Reduces coupling between software components Makes software more extensible
21	Hibernate with JTA for SOA Concepts (cont.) So, we want to use and RDBMS with OOPL… What’s the problem? Object-relational Impedance Mismatch
22	Hibernate with JTA for SOA Concepts (cont.) Object Relational Modeling (ORM) Bridges the gap between object based software and relational persistence Maintain data as objects in software which provides: Inheritance, Encapsulation, Polymorphism Persist data in a Relational Database that is useful for: Reporting / Extracts Ad Hoc Queries Maintain Referential and Data Integrity Automated (transparent) mapping of in memory objects to associated relational database tables for CRUD and search operations. Allows programmers inside of code to treat the data as standard objects and maintain object oriented design principles and patterns
23	Hibernate with JTA for SOA Concepts (cont.) Example: map object oriented software to a relational database
24	Hibernate with JTA for SOA ORM Basic Concepts Mapping of database rows to objects Entities and their Attributes Entity Associations Multiplicity One-to-One, One-to-Many, Many-to-Many Directional relationships Ex. OrderItem ß à Order Inheritance Table-per-class, table-per-subclass, table-per-concrete-class Mapping Metadata Describes the objects and their mapping to underlying database tables Type conversion Automatic Type conversion Ex. Varchar2 à String à Varchar2 User defined type conversion Locking schemes Optimistic / Pessimistic
25	Hibernate with JTA for SOA ORM Basic Concepts (cont.) Lazy association loading Collection classes (Maps, Sets, Ordered Sets, etc…) Support Transactions (unit of work) Caching Queries Specialized Query Languages (i.e. HQL, JPAQL) Support for Native SQL Named Queries Encapsulation of SQL generation Database platform becomes a configuration item Transitive Persistence (Cascade) Automatic “dirty checking”
26	Hibernate with JTA for SOA Hibernate ORM solution Provides persistence for Plain Old Java Objects (POJOs) Persistence mechanism for Java (standalone) and J2EE (application server) Supports inheritance, polymorphism, encapsulation, composition Open Source (GNU Lesser General Public License) Doesn’t require preprocessing or extra code generation Accessible through Hibernate API or Java Persistence API (EJB 3.0) “Hibernate's goal is to relieve the developer from 95 percent of common data persistence related programming tasks, compared to manual coding with SQL and the JDBC API.”
27	Hibernate with JTA for SOA Hibernate (cont.) Hibernate modules Hibernate Core Hibernate for Java, native APIs and XML mapping metadata Hibernate Annotations Map classes with JDK 5.0 annotations Hibernate EntityManager Standard Java Persistence API for Java SE and Java EE
28	Hibernate with JTA for SOA Hibernate (cont.) Hibernate API Hibernate Queries Hibernate Query Language (HQL) Object based, not schema based Results are retrieved as objects or sets of objects Support for major SQL functions and operators (i.e. left\|right outer join, group by, min, max, sum, subselects, etc…) Support for dynamic fetch parameters Criteria based queries Polymorphic queries Native Queries Option to write your own JDBC SQL queries Hibernate still provides a translation of results into objects
29	Hibernate with JTA for SOA Hibernate (cont.) Hibernate API (cont.) Additional features: Automated support for conversion between database variants and Java datatypes Support for custom data types Automatic “dirty checking” Supports long-lived persistence contexts through detach/reattach Support for extensive subset of the Java Collections API (with indexing) Inheritance (Table-per-class, table-per-subclass, table-per-concrete-class) Transitive persistence (cascades) Optimistic and Pessimistic locking
30	Hibernate with JTA for SOA Hibernate (cont.) Hibernate API (cont.) SessionFactory Heavyweight object created once. Reads configuration files and metadata mapping files Provides access to the Hibernate Session Session Lightweight object used to perform most persistent operations Provides Persistence Context (cache) Responsible for keeping registered persistent objects in sync with the database
31	Hibernate with JTA for SOA Hibernate (cont.) Hibernate API (cont.) Entity States
32	Hibernate with JTA for SOA EJB3.0 / JPA Overview EJB 3.0 is not EJB 2.0 (Entity Beans) Standardizes Java ORM into a common API Vendors provide implementations of the API Hibernate, TopLink, OpenJPA, Kodo, etc… Consortium of industry leading experts contributed Shows a clear influence from Spring in its use of POJO’s and dependency injection Hibernate’s influence is even more obvious. JPA API is very similar to Hibernate Most features in Hibernate were incorporated into the JPA You do not need an EJB container or Java EE application server in order to run applications that use JPA persistence.
33	Hibernate with JTA for SOA EJB3.0 / JPA Specifics EntityManagerFactory Session Factory EntityManager Session
34	Hibernate with JTA for SOA EJB3.0 / JPA Specifics (cont.) JPA vs. Native Hibernate Configuration META-INF/persistence.xml Criteria Based Queries Custom Data Types JPA QL Subset of HQL All queries in JPA QL are valid in HQL Optimistic Locking Vendor extensions
35	Example Example
36	Example @Entity @Table(name=‘EMPLOYEE’) public abstract class Employee { @Id @Column(name=‘TAX_ID’) private Long employeeId; @Column(name=‘FIRST_NAME’) private String firstName; @Column(name=‘LAST_NAME’) private String lastName; . . . }
37	Example @Entity @Table(name=‘EMPLOYEE’) @Inheritance( strategy = InheritanceType.SINGLE_TABLE ) @DiscriminatorColumn ( name=‘SOURCE_RQST_TYPE’, discriminatorType=DiscriminatorType.STRING ) public abstract class Employee { @Id @Column(name=‘TAX_ID’) private Long employeeId; @Column(name=‘FIRST_NAME’) private String firstName; @Column(name=‘LAST_NAME’) private String lastName; . . . }
38	Example @Entity @DiscriminatorValue( ‘SAL‘ ) public abstract class SalariedEmployee extends Employee { @Column(name=‘ANNUAL_SALARY’) private Double annualSalary; . . . }
39	Example @Entity @DiscriminatorValue( ‘HRLY‘ ) public abstract class HourlyEmployee extends Employee { @Column(name=‘HOURLY_RATE’) private Double hourlyRate; @OneToMany( mappedBy=‘employee‘, cascade = CascadeType.ALL) public Collection<Timecard> timecards; . . . }
40	Example @Entity @Table(name=‘TIMECARD’) public class Timecard { @Id @Column(name=‘TIMECARD_ID’) private Long timecardId; @Column(name=‘HOURS_WORKED’) private float hoursWorked; @ManyToOne @JoinColumn( name=‘TAX_ID‘ ) Private Employee employee; . . . }
41	Example configuration (persistence.xml): <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd version="1.0"> <persistence-unit name="payroll-entities" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>com.company.payroll.Employee</class> <class>com.company.payroll.SalariedEmployee</class> <class>com.company.payroll.HourlyEmployee</class> <class>com.company.payroll.Timecard</class> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect"/> <property name="hibernate.show_sql" value="true" /> </properties> </persistence-unit> </persistence>
42	"EntityManagerFactory entityFactory = Persistence.createEntityManagerFactory(‘..." EntityManagerFactory entityFactory = Persistence.createEntityManagerFactory(‘manager’); EntityManager em = entityFactory.createEntityManager(); Employee employee = new HourlyEmployee(12345,‘Ben’,’Franklin’,7.55d); em.persist(employee); Timecard t1 = new Timecard(1, 50.00); Timecard t2 = new Timecard(2, 80.00); employee.addTimecard(t1); employee.addTimecard(t2); em.flush()
43	"Query aQuery = em.createQuery(‘..." Query aQuery = em.createQuery(‘from Employee where firstName=‘John’’); List<Employee> results = aQuery.getResultList(); Iterator<Employee> listIter = results.iterator(); While (listIter.hasNext()) { Employee e = listIter.next(); System.out.println(e. getFirstName() + ‘earned: ‘ + e.calculatePay()); }
44	Hibernate with JTA for SOA Resources Java Persistence with Hibernate, Gavin King and Christian Bauer, Manning Publications, C 2007 http://www.hibernate.org/5.html, JBoss Labs hibernate website – User / developer documentation Sun Microsystems Java Persistence API website – User / developer documentation: http://java.sun.com/javaee/technologies/persistence.jsp