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connection_pooling_with_jpa_and_karaf [2015/06/19 17:02]
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connection_pooling_with_jpa_and_karaf [2021/04/05 11:23] (current)
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| | ====== Connection Pooling with JPA and Apache Karaf ====== |
| | This has been tested with Apache Karaf 3.0.3 and by installing the following features: |
| |
| | feature:install scr jpa/2.0.0 openjpa/2.2.2 transaction jndi jdbc |
| | |
| | ===== JDBC Driver ===== |
| | PostgreSQL is used in this example. The driver can be retrieved as a bundle from the Apache Servicemix project. Look in the [[http://search.maven.org | Maven Repository]] for ''org.apache.servicemix.bundles.postgresql''. |
| | |
| | Just drop the bundle into the ''deploy'' folder and set the bundle start level to 25. |
| | |
| | <note>I think the low bundle level is necessary because it the driver need to be started before the Aries JPA stuff so that it can pick up any Drivers. But I might be wrong with this one.</note> |
| | |
| | ===== DataSource ===== |
| | The ''javax.sql.DataSource'' instances will be created via Blueprint. Create a ''OSGI-INF/blueprint/blueprint.xml'' file in your project which looks like this: |
| | |
| | <sxh xml> |
| | <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" |
| | xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.1.0"> |
| | |
| | <reference id="transactionManager" interface="javax.transaction.TransactionManager" /> |
| | |
| | <!-- Configuration Admin suppport --> |
| | <cm:property-placeholder persistent-id="sdm.persistence.datasource" update-strategy="reload" /> |
| | |
| | <bean class="org.postgresql.ds.PGSimpleDataSource" id="sdsDatasource"> |
| | <property name="serverName" value="${host}" /> |
| | <property name="databaseName" value="${database}" /> |
| | <property name="user" value="${user}" /> |
| | <property name="password" value="${password}" /> |
| | </bean> |
| | |
| | <bean class="org.postgresql.xa.PGXADataSource" id="xaDatasource"> |
| | <property name="serverName" value="${host}" /> |
| | <property name="databaseName" value="${database}" /> |
| | <property name="user" value="${user}" /> |
| | <property name="password" value="${password}" /> |
| | </bean> |
| | |
| | <bean class="org.apache.commons.dbcp2.managed.BasicManagedDataSource" id="xaSdsDatasource" destroy-method="close"> |
| | <property name="xaDataSourceInstance" ref="xaDatasource" /> |
| | <property name="transactionManager" ref="transactionManager" /> |
| | <property name="maxTotal" value="25" /> |
| | <property name="initialSize" value="3" /> |
| | </bean> |
| | |
| | <service id="sdsDS" interface="javax.sql.DataSource" ref="sdsDatasource"> |
| | <service-properties> |
| | <entry key="osgi.jndi.service.name" value="jdbc/sds" /> |
| | </service-properties> |
| | </service> |
| | |
| | <service id="xaSdsDS" interface="javax.sql.DataSource" ref="xaSdsDatasource"> |
| | <service-properties> |
| | <entry key="osgi.jndi.service.name" value="jdbc/xasds" /> |
| | </service-properties> |
| | </service> |
| | |
| | </blueprint> |
| | </sxh> |
| | |
| | If you have any questions about this file, look at the OSGi Blueprint specs. |
| | |
| | <note tip>''BasicManagedDataSource'' is packaged in the ''commons-dbcp2'' project (which has a dependency to ''commons-pool2''). Both projects are already packaged as bundles and can be fetched from the maven repository.</note> |
| | |
| | The placeholders are filled by the ConfigAdmin service. It uses the configuration file //sdm.persistence.datasource// as stated in the attribute ''persistent-id'' which resides in the ''etc'' folder of Karaf. It may look something like this: |
| | |
| | <code> |
| | service.pid=sdm.persistence.datasource |
| | host=server |
| | database=my_db |
| | user=sgbs |
| | password=sgbs |
| | </code> |
| | |
| | The DataSource instances can be checked via |
| | |
| | service:list DataSource |
| | |
| | ===== JPA ===== |
| | Now the JPA needs to use our DataSource instances for getting a connection. This can be done in the ''persistence.xml'' file. |
| | |
| | It may look something like this: |
| | |
| | <sxh 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="sdm" transaction-type="JTA"> |
| | <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider> |
| | |
| | <jta-data-source>osgi:service/jdbc/xasds</jta-data-source> |
| | <non-jta-data-source>osgi:service/jdbc/sds</non-jta-data-source> |
| | |
| | <class>my.jpa.EntityClass</class> |
| | |
| | <properties> |
| | <property name="openjpa.Log" value="File=/tmp/org.apache.openjpa.log, DefaultLevel=TRACE" /> |
| | <property name="openjpa.RuntimeUnenhancedClasses" value="supported" /> |
| | </properties> |
| | |
| | </persistence-unit> |
| | |
| | </persistence> |
| | </sxh> |
| | |
| | |
| | <note important>Transaction testing still needs to be done!</note> |
| | |
| | |
| | ===== Other Solutions ===== |
| | |
| | ==== Pax JDBC ==== |
| | The project [[https://ops4j1.jira.com/wiki/display/PAXJDBC | Pax JDBC]] offers a nice solution to for creating DataSource objects via ConfigAdmin and also supports connection pooling. |