Apache Camel框架之事务控制

晨曦之光 发布于 2012/04/25 16:16
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本文简单介绍一下Apache Camel如何对route进行事务控制,首先介绍整个route只涉及到一个事务参与者的情况,然后再介绍route中涉及到多个事务参与者的情况.Camel是通过和Spring的框架集成进行事务控制的.

1,整个route只有一个事务参与者,"局部事务",这里用JMS的例子,后台的MQ为ActiveMQ,示例图如下:(图片来源于Camel in Action)


route的代码如下:

public class JMSTransaction extends RouteBuilder {
    public void configure() throws Exception {
        TProcessor0 p0 = new TProcessor0();
        TProcessor1 p1 = new TProcessor1();
        from("jms:queue:TOOL.DEFAULT").process(p0).process(p1).to("file:d:/temp/outbox");        
    }
}

Spring配置如下:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:broker="http://activemq.apache.org/schema/core"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
       http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
       http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core-5.2.0.xsd">
    <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
        <package>
            com.test.camel.transaction.jms
        </package>
    </camelContext>    
    <bean id="jms" class="org.apache.activemq.camel.component.ActiveMQComponent">
        <property name="transacted" value="true"/>
        <property name="transactionManager" ref="txManager"/>            
    </bean>
    <bean id="txManager" class="org.springframework.jms.connection.JmsTransactionManager">
        <property name="connectionFactory" ref="jmsConnectionFactory"/>
    </bean>
    <bean id="jmsConnectionFactory" class="org.apache.activemq.ActiveMQConnectionFactory">
        <property name="brokerURL" value="tcp://localhost:61616"/>        
    </bean>
</beans>

route定义的逻辑为从queue里取消息,然后进行一系列的处理(process(p0).process(p1)),<property name="transacted" value="true"/>的意思是通过这个jms进行的消息存取是有事务控制的.上面的route在process(p1)里抛出异常,txManager会进行rollback处理.(在activeMQ里,消息默认会redelivery到客户端6次,如果继续异常,消息会放到deadletter queue里(ActiveMQ.DLQ)),需要在AciveMQ的配置文件activemq.xml里配置如下:(non-persistent的queue的消息出错也转到dead letter queue)

<policyEntry queue=">">
 <deadLetterStrategy>
   <sharedDeadLetterStrategy processNonPersistent="true" />
 </deadLetterStrategy>

如果<property name="transacted" value="false"/>的话,消息在重发了6次后会丢失.

如果上面例子中的事务参与者是数据库的话,道理与之类似,只是配置的transaction manager不同,如:

<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"/>

Camel里使用ActiveMQ JMS的例子可以参照 http://blog.csdn.net/kkdelta/article/details/7237096

2,Camel里的全局事务,一个route里有多个事务参与者,示例图如下:(图片来源于Camel in Action)


route的定义如下:

public class XaTransaction extends RouteBuilder {
    public void configure() throws Exception {
        TProcessor1 p1 = new TProcessor1();
        from("jms:queue:TOOL.DEFAULT")
        .transacted()
        .log("+++ before database +++")
        .bean(SQLBean.class, "toSql")
        .to("jdbc:myDataSource")
        .process(p1)
        .log("+++ after database +++");
    }
}
public class SQLBean {
    public String toSql(String str) {
        //create table CamelTEST(msg varchar2(2000));
        StringBuilder sb = new StringBuilder();
        sb.append("INSERT INTO CamelTEST VALUES ('camel test')");
        return sb.toString();
    }
}

route的逻辑是从queue里取消息,然后操作数据库,然后做后续其他操作(process(p1)),这里的process(p1)如果抛出异常的话,取消息和数据库操作都回滚,

如果整个route都成功完成的话,取消息和数据库操作提交.

这里用到JTA transaction manager是atomikos,相应的jar包可以从这里下载:http://download.csdn.net/detail/kkdelta/4056226

atomikos的主页 http://www.atomikos.com/Main/ProductsOverview

Spring的配置如下:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:broker="http://activemq.apache.org/schema/core"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
       http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
       http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core-5.2.0.xsd">   
    <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
        <package>
            com.test.camel.transaction.xa
        </package>
    </camelContext>
    <bean id="atomikosTransactionManager"
          class="com.atomikos.icatch.jta.UserTransactionManager"
          init-method="init" destroy-method="close" >
        <!-- when close is called, should we force transactions to terminate or not? -->
        <property name="forceShutdown" value="false"/>
    </bean>
    <!-- this is some atomikos setup you must do -->
    <bean id="atomikosUserTransaction" class="com.atomikos.icatch.jta.UserTransactionImp" >
        <property name="transactionTimeout" value="300"/>
    </bean>
    <!-- this is some atomikos setup you must do -->
    <bean id="connectionFactory"
          class="com.atomikos.jms.AtomikosConnectionFactoryBean" >
        <property name="uniqueResourceName" value="amq1"/>
        <property name="xaConnectionFactory" ref="jmsXaConnectionFactory"/>
    </bean>
    <!-- this is the Spring JtaTransactionManager which under the hood uses Atomikos -->
    <bean id="jtaTransactionManager"
          class="org.springframework.transaction.jta.JtaTransactionManager" >
        <property name="transactionManager" ref="atomikosTransactionManager"/>
        <property name="userTransaction" ref="atomikosUserTransaction"/>
    </bean>
    <!-- Is the ConnectionFactory to connect to the JMS broker -->
    <!-- notice how we must use the XA connection factory -->
    <bean id="jmsXaConnectionFactory" class="org.apache.activemq.ActiveMQXAConnectionFactory" >
        <property name="brokerURL" value="tcp://localhost:61616"/>
    </bean>
    <!-- define the activemq Camel component so we can integrate with the AMQ broker below -->
    <bean id="jms" class="org.apache.activemq.camel.component.ActiveMQComponent" >
        <property name="transacted" value="true"/>
        <property name="transactionManager" ref="jtaTransactionManager"/>
    </bean>
   <bean id="myDataSource" 
      class="com.atomikos.jdbc.AtomikosDataSourceBean" 
      init-method="init" destroy-method="close"> 
       <!-- set an arbitrary but unique name for the datasource --> 
      <property name="uniqueResourceName"><value>XADBMS</value></property> 
      <property name="xaDataSourceClassName"> 
         <value>oracle.jdbc.xa.client.OracleXADataSource</value> 
      </property> 
      <property name="xaProperties"> 
                <props> 
                        <prop key="user">xxx</prop> 
                        <prop key="password">xxx</prop> 
                        <prop key="URL">jdbc:oracle:thin:@147.151.240.xxx:1521:orcl</prop>
                </props> 
      </property>    
      <property name="poolSize" value="1"/> 
   </bean>    
</beans>


原文链接:http://blog.csdn.net/kkdelta/article/details/7249122
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