检测ActiveMQ主题的使用者变化 [英] Detect change in Consumers of an ActiveMQ topic
问题描述
我有一堆tomcat,它们使用ActiveMQ主题中的消息.现在,如果集群中的tomcat之一发生故障,那么我猜认为该用户数量将下降1.
I have a cluster of tomcats which consume messages from an ActiveMQ topic. Now, if one of the tomcat in the cluster goes down then i am guessing that number of consumers would go down by 1.
现在,我想使用有关该主题的一些回调或侦听器来检测该更改.那可行吗?
Now, i would like to detect that change using some callback or listener on that topic. Is that feasible ?
诸如:Region.getDestinations(ActiveMQDestination)会起作用吗?
Will something like : Region.getDestinations(ActiveMQDestination) work ?
推荐答案
咨询消息是您所需要的.
Advisory Message is what you need.
每次收到包含此代码的消息时,这表示您开始或停止消费.
each time you got a message with this code this means you have consumer starting or stopping.
doc http://activemq.apache.org/advisory-message.html
示例:
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.Queue;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.command.ActiveMQMessage;
import org.apache.activemq.command.ConsumerInfo;
import org.apache.activemq.command.RemoveInfo;
public class AdvisorySupportConsumerAdvisoryTopic {
public static void main(String[] args) throws JMSException {
Connection conn = null;
try {
ConnectionFactory cf = new ActiveMQConnectionFactory("auto://localhost:5671");
conn = cf.createConnection("admin", "admin");
ActiveMQSession session = (ActiveMQSession) conn.createSession(false,
ActiveMQSession.INDIVIDUAL_ACKNOWLEDGE);
conn.start();
Queue q = session.createQueue("Q");
Destination advisoryDestination = org.apache.activemq.advisory.AdvisorySupport.getConsumerAdvisoryTopic(q);
MessageConsumer consumer = session.createConsumer(advisoryDestination);
consumer.setMessageListener(new MessageListener() {
@Override
public void onMessage(Message msg) {
if (msg instanceof ActiveMQMessage) {
try {
ActiveMQMessage aMsg = (ActiveMQMessage) msg;
System.out.println(aMsg.getStringProperty("consumerCount"));
System.out.println(aMsg.getStringProperty("producerCount"));
if (aMsg.getDataStructure() instanceof ConsumerInfo) {
// Consumer start
ConsumerInfo consumerInfo = (ConsumerInfo) aMsg.getDataStructure();
System.out.println(consumerInfo);
} else if (aMsg.getDataStructure() instanceof RemoveInfo) {
// Consumer stop
RemoveInfo removeInfo = (RemoveInfo) aMsg.getDataStructure();
System.out.println(removeInfo);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
} catch (Exception e) {
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
}
}
}
}
}
每次收到带有此代码的消息时,这表示您已连接开始或停止.
each time you got a message with this code this means you have Connection starting or stopping.
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.command.ActiveMQMessage;
import org.apache.activemq.command.ConnectionInfo;
import org.apache.activemq.command.RemoveInfo;
public class AdvisorySupportConnectionAdvisoryTopic {
public static void main(String[] args) throws JMSException {
Connection conn = null;
try {
ConnectionFactory cf = new ActiveMQConnectionFactory("auto://localhost:5671");
conn = cf.createConnection("admin", "admin");
ActiveMQSession session = (ActiveMQSession) conn.createSession(false,
ActiveMQSession.INDIVIDUAL_ACKNOWLEDGE);
conn.start();
Destination advisoryDestination = org.apache.activemq.advisory.AdvisorySupport.getConnectionAdvisoryTopic();
MessageConsumer consumer = session.createConsumer(advisoryDestination);
consumer.setMessageListener(new MessageListener() {
@Override
public void onMessage(Message msg) {
if (msg instanceof ActiveMQMessage) {
try {
ActiveMQMessage aMsg = (ActiveMQMessage) msg;
if (aMsg.getDataStructure() instanceof ConnectionInfo) {
// Connection start
ConnectionInfo connectionInfo = (ConnectionInfo) aMsg.getDataStructure();
System.out.println(connectionInfo);
} else if (aMsg.getDataStructure() instanceof RemoveInfo) {
// Connection stop
RemoveInfo removeInfo = (RemoveInfo) aMsg.getDataStructure();
System.out.println(removeInfo);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
} catch (Exception e) {
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
}
}
}
}
}
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