Blueprint入门之八
Blueprint除了组装bean,osgi服务引用等的DI（IOC）功能之外，还可通过各种命名空间（namespace）来扩展。在《Blueprint入门之六》中，我们就用过一个与ConfigAdmin相关的命名空间（http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0）。
除了ConfigAdmin之外，我们还可以看到aries JPA container提供了JPA相关的blueprint命名空间（http://aries.apache.org/xmlns/jpa/v1.1.0） ，Aries JPA Container根据bundle中的persistence.xml构建持久化域单元（persistence domain unit）后，需要将相应的EntityManagerFactory或EntityManager注入到需要用到该持久化域的bean实例里，就可以使用这个命名空间。
persistence.xml:
<?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=" com.ponder.myPU " transaction-type="RESOURCE_LOCAL"> <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider> <non-jta-data-source>osgi:service/javax.sql.DataSource/(osgi.jndi.service.name=jdbc/myDS)</non-jta-data-source> <class>com.ponder.*</class> <properties> <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"/> </properties> </persistence-unit></persistence>
<?xml version="1.0" encoding="UTF-8"?><blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:jpa="http://aries.apache.org/xmlns/jpa/v1.1.0" > <bean id="processor1" unitname="com.ponder.myPU" /> </bean> ... ....</blueprint>
<?xml version="1.0" encoding="UTF-8"?><blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:jpa="http://aries.apache.org/xmlns/jpa/v1.1.0" > <bean id="processor1" unitname="com.ponder.myPU" /> </bean>... ....</blueprint>
<?xml version="1.0" encoding="UTF-8"?><blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"xmlns:jpa="http://aries.apache.org/xmlns/jpa/v1.0.0"xmlns:tx="http://aries.apache.org/xmlns/transactions/v1.0.0"><bean id="processor1" unitname="com.ponder.myPU" /> <tx:transaction method="*" value="Required" /></bean>... ...</blueprint>
