I'm not able to get this persistence file correct... I do not find any more information in the book that I use as a guide. I'm using a MySQL database.
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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_2_0.xsd">
<persistence-unit name="a11_DA_g5_PU" transaction-type="JTA">
<jta-data-source>a11_DA_g5</jta-data-source>
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>entities.Book</class>
<class>entities.Author</class>
<class>entities.Customer</class>
<class>entities.Membership</class>
<properties>
<property name="eclipselink.target-database" value="DERBY"/>
<property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://studev.groept.be:3306/a11_DA_g5"/>
<property name="javax.persistence.jdbc.user" value="a11_DA_g5"/>
<property name="javax.persistence.jdbc.password" value="passwordhere"/>
<property name="eclipselink.ddl-generation" value="create-tables"/>
</properties>
</persistence-unit>
</persistence>
EDIT
SEVERE: DPL8015: Invalid Deployment Descriptors in Deployment descriptor file META-INF/persistence.xml in archive [EJBModule_jar]. Line 6 Column 15 -- cvc-complex-type.2.4.a: Invalid content was found starting with element 'provider'. One of '{"http://java.sun.com/xml/ns/persistence":shared-cache-mode, "http://java.sun.com/xml/ns/persistence":validation-mode, "http://java.sun.com/xml/ns/persistence":properties}' is expected.
SEVERE: DPL8005: Deployment Descriptor parsing failure : cvc-complex-type.2.4.a: Invalid content was found starting with element 'provider'. One of '{"http://java.sun.com/xml/ns/persistence":shared-cache-mode, "http://java.sun.com/xml/ns/persistence":validation-mode, "http://java.sun.com/xml/ns/persistence":properties}' is expected.
SEVERE: Exception while deploying the app [VaadinTestApp]
SEVERE: org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'provider'. One of '{"http://java.sun.com/xml/ns/persistence":shared-cache-mode, "http://java.sun.com/xml/ns/persistence":validation-mode, "http://java.sun.com/xml/ns/persistence":properties}' is expected. java.io.IOException: org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'provider'. One of '{"http://java.sun.com/xml/ns/persistence":shared-cache-mode, "http://java.sun.com/xml/ns/persistence":validation-mode, "http://java.sun.com/xml/ns/persistence":properties}' is expected.