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Chapter 9. Hibernate on Enterprise Web Server

Hibernate is an object-relational mapping framework. It is delivered in a separate package and the same package can be used on all supported platforms.
Hibernate can be used in the same way it is used in a regular Tomcat installation; that is, the Hibernate JAR files can be added into your deployment WAR file. Tomcat provides a connection pooling mechanism by default, and you should consider taking advantage of it (the pooling mechanism is defined in the context.xml). However, persistence.xml and web.xml are required. The example below shows a setting with tomcat connection pooling mechanism.
  • /META-INF/context.xml defines the connection pools Tomcat should create.

    Example 9.1. context.xml

    <Context>
  <Resource
    name="jdbc/DsWebAppDB"
    auth="Container"
    type="javax.sql.DataSource"
    username="sa"
    password=""
    driverClassName="org.h2.Driver"
    url="jdbc:h2:mem:target/test/db/h2/hibernate 
    maxActive="8"
    maxIdle="4"/>
</Context>
  • /WEB-INF/classes/META-INF/persistence.xml is a JPA configuration file. It defines how the application configures Hibernate to consume connections from the Tomcat pool. If you are using Hibernate API directly, use a similar configuration in hibernate.cfg.xml.

    Example 9.2. persistence.xml

    <persistence version="1.0"
  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">

  <persistence-unit name="dswebapp">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
      <property name="hibernate.connection.datasource" value="java:comp/env/jdbc/DsWebAppDB"/>
    </properties>
  </persistence-unit>
</persistence>
  • /WEB-INF/web.xml is a regular web application deployment file, which tells Tomcat which datasource it consumes. In Example 9.3, “web.xml” the datasource is jdbc/DsWebAppDB.

    Example 9.3. web.xml

    <?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

 <resource-env-ref>
  <resource-env-ref-name>jdbc/DsWebAppDB</resource-env-ref-name>
  <resource-env-ref-type>javax.sql.DataSource</resource-env-ref-type>
 </resource-env-ref>
</web-app>
For details, refer to the Hibernate documentation for JBoss Enterprise Web Server.