I have an in-memory data source:
java.sql.Connection c = DriverManager.getConnection(\"jdbc:hsqldb:mem:testdb\", \"sa\", \"\");
emf = Persistence
/*What to enter here?*/
Well, nothing. In a Java SE environment, you'll have to use the built-in connection pool from your JPA provider and the setup looks like this:
<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_2_0.xsd" version="2.0">
<persistence-unit name="manager" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>com.acme.Foo</class>
...
<properties>
<property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:mem:testdb"/>
<property name="javax.persistence.jdbc.user" value="sa"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
</persistence>