Java 了解Seam2/Tomcat7环境中JPA/Hibernate的连接池/事务

看到这3份文件，我得出结论： 1此应用程序使用JPA和Hibernate作为提供程序？！ 2连接池由tomcatcontext.xml控制？！ 3.交易情况如何？Seamframework容器是否控制此处的事务？或者没有事务控制器！？ 4如果2是真的，那么如果我想用hibernate的C3PO来交换连接池，这个更改会产生多大的影响

components.xml

<persistence:entity-manager-factory name="entityManagerFactory" persistence-unit-name="sampleDatabase" />
<persistence:managed-persistence-context entity-manager-factory="#{entityManagerFactory}" name="entityManager" />
<factory auto-create="true" name="hibernateSession" value="#{entityManager.delegate}" />
<transaction:entity-transaction entity-manager="#{entityManager}" />

persistence.xml

<persistence-unit name="sampleDatabase">
    <non-jta-data-source>java:comp/env/sampleDatasource</non-jta-data-source>
    <properties>
        <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect" />
        <property name="hibernate.jdbc.batch_size" value="20"/>
        <property name="hibernate.connection.provider_class" value="com.sample.util.RoleProvider" />
    </properties>
</persistence-unit>

context.xml

<Resource auth="Container"
          name="sampleDatasource"
          type="javax.sql.DataSource"
          driverClassName="oracle.jdbc.driver.OracleDriver"
          maxActive="2"
          maxIdle="1"
          username="sample"
          password="sample"
          url="jdbc:oracle:thin:@myserver:1521:DESENV" />