JavaEE: JPA persistence.xml and DataSource on TomEE

All applications need to create, retrieve, update, and delete data, and most applications use a relational database.  In the JDBC API, database are accessed by using DataSource object, which may be registered with a JNDI naming service.  Applications that use the JPA specify the DataSource object in the jta-data-source element of the persistence.xml file.

By default, TomEE uses the OpenJPA, but the hibernate is more commonly used in the software industry. So, I will use the hibernate and the PostgreSQL database.

persistence.xml
The JPA requires a persistence unit defined in a persistence.xml, which has to be located in the META-INF directory.  In the maven project created with the default directory structure, the META-INF directory is located under the src/main/resources directory.  One persistence.xml file can have more than one persistence unit definition, but I use one persistence unit here.  The persistence-unit demoDB uses a JTA for the transaction.

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">

  <persistence-unit name="demoDB" transaction-type="JTA">
    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

    <jta-data-source>demoDS</jta-data-source>
    <class>demo.model.entity.User</class>
    

    <shared-cache-mode>NONE</shared-cache-mode> 
    <properties>
      <property name="hibernate.dialect" value="PostgreSQL9"/>
      <property name="hibernate.show_sql" value="true" />
      <property name="hibernate.format_sql" value="true" />
      
      <property name="tomee.jpa.factory.lazy" value="true" />
      <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
    </properties>

  </persistence-unit>
</persistence>

On this file, I defined a jta-data-source element 'demoDS' but where did we define the DataSource?

resources.xml on TomEE
On the TomEE, a DataSource can be defined in the <TomEE-HOME>/conf/tomee.xml file or in a WEB-INF/resources.xml.  This is my Resource declaration in the resources.xml, but more properties, which are optional, are explained in a TomEE website: http://tomee.apache.org/datasource-config.html

<?xml version='1.0' encoding='UTF-8'?>
<resources>
  <Resource id="demoDS" type="javax.sql.DataSource">
    jdbcDriver = org.postgresql.Driver
    jdbcUrl = jdbc:postgresql://localhost:5555/demoDB
    password = password
    passwordCipher = PlainText
    userName = postgres
  </Resource>
</resources>

On the next post, we will make a database connection using this persistence unit.

pom.xml used
This is very minimal pom.xml to save the space.  Depends on your needs, you may include more hibernate dependencies.  A reference on a TomEE webpage: http://tomee.apache.org/tomee-and-hibernate.html

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <groupId>com.jihwan.jee</groupId>
  <artifactId>demo</artifactId>
  <version>0.1-SNAPSHOT</version>
  <packaging>war</packaging>

  <properties>
    <tomee.version>7.0.2</tomee.version>
    <!-- openejb.javaee.api>6.0-6</openejb.javaee.api> -->
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <failOnMissingWebXml>false</failOnMissingWebXml>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.source>1.8</maven.compiler.source>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.apache.tomee</groupId>
      <artifactId>tomee-embedded</artifactId>
      <version>${tomee.version}</version>
      <scope>provided</scope>
      <exclusions>
         <exclusion>
            <groupId>org.apache.openjpa</groupId>
            <artifactId>openjpa</artifactId>
         </exclusion>
      </exclusions>
    </dependency>
    
    <dependency>
       <groupId>org.postgresql</groupId>
       <artifactId>postgresql</artifactId>
       <version>9.4.1212</version>
    </dependency>
    
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>5.2.10.Final</version>
      <exclusions>
        <exclusion>
          <groupId>org.hibernate.javax.persistence</groupId>
          <artifactId>hibernate-jpa-2.1-api</artifactId>
        </exclusion>
        <exclusion>
          <groupId>org.jboss.spec.javax.transaction</groupId>
          <artifactId>jboss-transaction-api_1.2_spec</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
    
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-entitymanager</artifactId>
      <version>5.2.10.Final</version>
      <exclusions>
         <exclusion>
             <groupId>org.hibernate.javax.persistence</groupId>
             <artifactId>hibernate-jpa-2.1-api</artifactId>
         </exclusion>
         <exclusion>
             <groupId>org.jboss.spec.javax.transaction</groupId>
             <artifactId>jboss-transaction-api_1.2_spec</artifactId>
         </exclusion>
     </exclusions>
    </dependency>
  </dependencies>

  <build>
    <finalName>${project.artifactId}</finalName>
    <plugins>
      <plugin>
        <groupId>org.apache.tomee.maven</groupId>
        <artifactId>tomee-maven-plugin</artifactId>
        <version>${tomee.version}</version>
        <configuration>
          <tomeeVersion>${tomee.version}</tomeeVersion>
          <tomeeClassifier>plus</tomeeClassifier>
          
          <synchronization>
            <extensions>
              <extension>.class</extension>
            </extensions>
          </synchronization>

          <reloadOnUpdate>true</reloadOnUpdate>
          <systemVariables>
            <tomee.serialization.class.blacklist>-</tomee.serialization.class.blacklist>
          </systemVariables>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>