ActiveMQ学习笔记（12）----ActiveMQ的集群
1. Queue consumer cluster
ActiveMQ支持Consumer对消息的高可靠性的负载均衡消费，如果一个Consumer死掉，该消息会转发到其他的Consumer消费的Queue。如果一个Consumer获得消息比其他Consumer快，那么他将获得更多的消息。因此推荐ActiveMQ的Broker和Client使用failover://transport的方式来配置连接
2. Broker clusters
大部分情况下是使用一系列的Broker和Client连接到一起。如果一个Broker死掉了，那么Client可以自动连接到其他的Broker上。实现以上行为需用failover协作Client.
如果启动了多个Broker，Client可以使用static discovery或者Dynamic discovery容易从一个broker到另一个broker直接连接。这样当一个broker上没有Consumer的话，那么它的消息不会被消费，然而该broker会通过存储和转发的策略来把该消息发送到其他broker上。
特别注意：ActiveMQ默认的两个Broker, static链接后是单方向的，broker-A可以访问消费Broker-b的消息，如果要支持双向通信，需要在networConnector配置的时候，设置duplex=true。
这里的集群使用的是静态网络连接，访问broker的时创建ConnectionFactory的路径应写为：
ConnectionFactory factory = new ActiveMQConnectionFactory("failover:(tcp://localhost:61616,tcp://localhost:61716)?randomize=false");
使用三个消费者，一个消费者连接端口61716，另外两个消费者连接61616端口。
三个消费者使用如下代码如下
package com.wangx.activemq.master;
import org.apache.activemq.ActiveMQConnectionFactory;
import javax.jms.*;
public class QR1 {
public static void main(String[] args) {
//创建链接工厂
ConnectionFactory factory = new ActiveMQConnectionFactory("failover:(tcp://localhost:61616,tcp://localhost:61716)?randomize=false");
Connection connection = null;
try{
//创建链接
connection = factory.createConnection();
//启动链接
connection.start();
//获取会话
final Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
//创建队列
Destination queue = session.createQueue("myQueue");
MessageConsumer consumer1 = session.createConsumer(queue);
MessageConsumer consumer2 = session.createConsumer(queue);
new Thread(new MasterRunnable(consumer1, session, "consumer1")).start();
new Thread(new MasterRunnable(consumer2, session, "consumer2")).start();
}catch (Exception e) {
e.printStackTrace();
}
}
}
线程任务类：开两个线程同时使用两个消费者同时监听61616端口
package com.wangx.activemq.master;
import javax.jms.JMSException;
import javax.jms.MessageConsumer;
import javax.jms.Session;
public class MasterRunnable implements Runnable {
private MessageConsumer consumer;
private Session session;
private String name;
public MasterRunnable(MessageConsumer consumer, Session session, String name) {
this.consumer = consumer;
this.session = session;
this.name = name;
}
@Override
public void run() {
try {
consumer.setMessageListener(new MyMessageListener(session, name));
} catch (JMSException e) {
e.printStackTrace();
}
}
}
消息监听类：
package com.wangx.activemq.master;
import javax.jms.*;
public class MyMessageListener implements MessageListener {
private Session session = null;
private String name;
public MyMessageListener(Session session, String name) {
this.session = session;
this.name = name;
}
@Override
public void onMessage(Message message) {
TextMessage textMessage = (TextMessage) message;
try {
System.out.println(name + "接受到消息：" + textMessage.getText());
session.commit();
} catch (JMSException e) {
e.printStackTrace();
}
}
}
连接61716端口的consumer
package com.wangx.activemq.master;
import org.apache.activemq.ActiveMQConnectionFactory;
import javax.jms.*;
public class QR2 {
public static void main(String[] args) {
//创建链接工厂
ConnectionFactory factory = new ActiveMQConnectionFactory("failover:(tcp://localhost:61616,tcp://localhost:61716)?randomize=false");
Connection connection = null;
try{
//创建链接
connection = factory.createConnection();
//启动链接
connection.start();
//获取会话
final Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
//创建队列
Destination queue = session.createQueue("myQueue");
//创建消费者
MessageConsumer messageConsumer = session.createConsumer(queue);
//监听消息
messageConsumer.setMessageListener(new MessageListener() {
@Override
public void onMessage(Message message) {
TextMessage textMessage = (TextMessage) message;
try {
System.out.println("QR2 接受到消息：" + textMessage.getText());
session.commit();
} catch (JMSException e) {
e.printStackTrace();
}
}
});
}catch (Exception e) {
}
}
}
向端口61716发送消息
package com.wangx.activemq.master;
import org.apache.activemq.ActiveMQConnectionFactory;
import javax.jms.*;
public class MessageSender {
public static void main(String[] args) throws JMSException {
//创建链接工厂
ConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61716");
Connection connection = null;
Session session = null;
try{
//创建链接
connection = factory.createConnection();
//启动链接
connection.start();
//获取会话
session = connection.createSession(Boolean.TRUE, session.AUTO_ACKNOWLEDGE);
//创建队列
Destination queue = session.createQueue("myQueue");
//创建生产者对象
MessageProducer messageProducer = session.createProducer(queue);
for (int i = 0; i < 30; i++) {
//创建消息对象
TextMessage textMessage = session.createTextMessage("hello:" + i);
//发送消息
messageProducer.send(textMessage);
System.out.println(textMessage.getText());
}
session.commit();
session.close();
connection.close();
}catch (Exception e) {
}finally {
}
}
}
分别启动两个消息监听类，可以发现，此时两个不同broker所连接的消费者所消费的消息是均分的，尽管此时有一个broker中有两个consumer,这是因为ActiveMQ默认的认为网络上的broker作为一个consumer，此时将conduitSubscriptions设置为false即可是整个集群上的所有consumer都有均分消费消息的可能。
2. Master Slave
在5.9的版本中，废除了Pure Master Slave的方式，目前支持
1. Shared File System Master Slave：基于共享存储的Master-Slave；多个broker实例使用一个存储文件，谁拿到文件锁谁就是master,其他处于待启动状态，如果master挂掉了，某个抢到文件锁的slave变成master
2. JDBC Master Slave: 基于JDBC的Master-Slave:使用同一个数据库，拿到LOCK表的写锁的broker成为master.
3. Replicated LeveDB Store:基于zookeeper复制LeveDB存储的Master-Slave机制，这个是5.9新家的机制。
具体的可以查看官方文档：
http://activemq.apache.org/masterslave.html
3. JDBC Master Slave方式
利用数据库作为数据源，采用Master/Slave模式，其中启动的时候Master首先获得独有锁，其他Slaves Broker等待获取独有锁。
推荐客户端使用Failover来连接Brokers.
具体如下图：
3.1. Master失败
如果master失败，则它释放独有锁，其他Slave获独有锁，其他Slave立即获得独有锁后它将变成Master,并且启动所有的传输连接。同时，Client将停止连接之前的Master并且它将会轮询其他可以利用到的Broker,即新的Master.如上中图所示。
3.2 Master重启
任何时候启动新的Broker,都会作为新的Slave来加入集群，如上右图所示。
3.3 JDBC Master Slave的配置
使用<jdbcPersistenceAdapter dataSource="#mysql-ds"/>来配置消息持久化，自动就会使用MasterSlave的方式。具体配置如下：
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<!-- START SNIPPET: example -->
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
<!-- Allows us to use system properties as variables in this configuration file -->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>file:${activemq.conf}/credentials.properties</value>
</property>
</bean>
<!-- Allows accessing the server log -->
<bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"
lazy-init="false" scope="singleton"
init-method="start" destroy-method="stop">
</bean>
<!--
The <broker> element is used to configure the ActiveMQ broker.
-->
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">
<destinationPolicy>
<policyMap>
<policyEntries>
<!--<policyEntry topic=">" >
The constantPendingMessageLimitStrategy is used to prevent
slow topic consumers to block producers and affect other consumers
by limiting the number of messages that are retained
For more information, see:
http://activemq.apache.org/slow-consumer-handling.html
<pendingMessageLimitStrategy>
<constantPendingMessageLimitStrategy limit="1000"/>
</pendingMessageLimitStrategy>
</policyEntry>-->
<policyEntry queue=">" enableAudit="false">
<networkBridgeFilterFactory>
<conditionalNetworkBridgeFilterFactory replayWhenNoConsumers="true"/>
</networkBridgeFilterFactory>
</policyEntry>
</policyEntries>
</policyMap>
</destinationPolicy>
<!--
The managementContext is used to configure how ActiveMQ is exposed in
JMX. By default, ActiveMQ uses the MBean server that is started by
the JVM. For more information, see:
http://activemq.apache.org/jmx.html
-->
<managementContext>
<managementContext createConnector="false"/>
</managementContext>
<!--
Configure message persistence for the broker. The default persistence
mechanism is the KahaDB store (identified by the kahaDB tag).
For more information, see:
http://activemq.apache.org/persistence.html
-->
<persistenceAdapter>
<!--<kahaDB directory="${activemq.data}/kahadb_2"/>-->
<jdbcPersistenceAdapter dataSource="#mysql-ds"/>
</persistenceAdapter>
<!--
The systemUsage controls the maximum amount of space the broker will
use before disabling caching and/or slowing down producers. For more information, see:
http://activemq.apache.org/producer-flow-control.html
-->
<systemUsage>
<systemUsage>
<memoryUsage>
<memoryUsage percentOfJvmHeap="70" />
</memoryUsage>
<storeUsage>
<storeUsage limit="100 gb"/>
</storeUsage>
<tempUsage>
<tempUsage limit="50 gb"/>
</tempUsage>
</systemUsage>
</systemUsage>
<!--
The transport connectors expose ActiveMQ over a given protocol to
clients and other brokers. For more information, see:
http://activemq.apache.org/configuring-transports.html
-->
<transportConnectors>
<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
<transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:9999?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
</transportConnectors>
<!--