ActiveMQ消息特性：通知消息（Advisory Message）

通知消息（Advisory Message）

简单的说就是实现了ActiveMQ的broker上各种操作的记录跟踪和通知。

使用这个功能，你可以实时的知道broker上

1. 创建或销毁了连接，
2. 添加或删除了生存者或消费者，
3. 添加或删除了主题或队列，
4. 有消息发送和接收，
5. 什么时候有慢消费者，
6. 什么时候有快生产者
7. 什么时候什么消息被丢弃
8. 什么时候broker被添加到集群（主从或是网络连接）

这个机制是ActiveMQ对JMS协议的重要补充，也是基于JMS实现的ActiveMQ的可管理性的一部分。多个ActiveMQ的相互协调和互操作的基础设置。

使用示例与注意事项

使用很简单，完全的jms方式，示例如下

...

    Destination advisoryDestination = AdvisorySupport.getProducerAdvisoryTopic(destination)
    MessageConsumer consumer = session.createConsumer(advisoryDestination);
    consumer.setMessageListener(this);
....
public void onMessage(Message msg){
    if (msg instanceof ActiveMQMessage){
        try {
             ActiveMQMessage aMsg =  (ActiveMQMessage)msg;
             ProducerInfo prod = (ProducerInfo) aMsg.getDataStructure();
        } catch (JMSException e) {
            log.error("Failed to process message: " + msg);
        }
    }
}

通过拿到的消息的数据结构，可以进一步的拿到相关操作信息。

而且Advisory消息都是先返回当前的所有存在数据，比如现在已经存在的所有连接或是队列信息，然后再实时通知你新创建和断开的连接，新添加或删除的队列等等。。。

ActiveMQ.Advisory.Queue 数据结构为DestinationInfo，先拿到broker上现有的所有队列列表
如果再有add或remove队列的操作，拿到通知，operationType=0为add，为1则为remove
为topic时，自动过滤掉Advisory的topic。

ActiveMQ.Advisory.Producer.Queue 数据结构为ProducerInfo，其中包含Producer的参数信息
ActiveMQ.Advisory.Consumer.Queue 数据结构为ConsumerInfo，其中包含Consumer的参数信息
使用的时候，需要以此为前缀，监听需要的队列，比如kk.adt,则应该写
Topic topic = new ActiveMQTopic("ActiveMQ.Advisory.Consumer.Queue.kk.adt");
监听所有队列则
Topic topic = new ActiveMQTopic("ActiveMQ.Advisory.Consumer.Queue..>");
Producer或Consumer断开时，数据结构为RemoveInfo。
主题的监听类似。

持久订阅者上线时是ConsumerInfo，里面有clientId和consumerId，下线时的RemoveInfo里有consumerId，跟上线时对应。

ActiveMQ内置了一些工具类，根据你需要监听的队列名，自动拼Advisory的名称：
例如 AdvisorySupport.getProducerAdvisoryTopic(new ActiveMQTopic("kk.adt"));

broker接收到或是投递消息的通知默认是关闭的。
需要在policy上设置相应的开关。 消息处理相关的Advisory的数据结构是消息本身。

客户端连接相关的通知消息 都是默认开启的

Advisory Topics	Description	properties	Data Structure
ActiveMQ.Advisory.Connection	Connection start & stop messages
ActiveMQ.Advisory.Producer.Queue	Producer start & stop messages on a Queue	String='producerCount' - the number of producers	ProducerInfo
ActiveMQ.Advisory.Producer.Topic	Producer start & stop messages on a Topic	String='producerCount' - the number of producers	ProducerInfo
ActiveMQ.Advisory.Consumer.Queue	Consumer start & stop messages on a Queue	String='consumerCount' - the number of Consumers	ConsumerInfo
ActiveMQ.Advisory.Consumer.Topic	Consumer start & stop messages on a Topic	String='consumerCount' - the number of Consumers	ConsumerInfo

队列和消息的通知消息  队列相关的是默认开启的，消息相关的都需要手工配置Pilocy选项开启

Advisory Topics	Description	properties	Data Structure	default	PolicyEntry property
ActiveMQ.Advisory.Queue	Queue create & destroy	null	null	true	none
ActiveMQ.Advisory.Topic	Topic create & destroy	null	null	true	none
ActiveMQ.Advisory.TempQueue	Temporary Queue create & destroy	null	null	true	none
ActiveMQ.Advisory.TempTopic	Temporary Topic create & destroy	null	null	true	none
ActiveMQ.Advisory.Expired.Queue	Expired messages on a Queue	String='orignalMessageId' - the expired id	Message	true	none
ActiveMQ.Advisory.Expired.Topic	Expired messages on a Topic	String='orignalMessageId' - the expired id	Message	true	none
ActiveMQ.Advisory.NoConsumer.Queue	No consumer is available to process messages being sent on a Queue	null	Message	false	sendAdvisoryIfNoConsumers
ActiveMQ.Advisory.NoConsumer.Topic	No consumer is available to process messages being sent on a Topic	null	Message	false	sendAdvisoryIfNoConsumers

从5.2版本新加的消息处理与性能相关的，都需要手工启动

Advisory Topics	Description	properties	Data Structure	default	PolicyEntry property
ActiveMQ.Advisory.SlowConsumer.Queue	Slow Queue Consumer	String='consumerId' - the consumer id	ConsumerInfo	false	advisoryForSlowConsumers
ActiveMQ.Advisory.SlowConsumer.Topic	Slow Topic Consumer	String='consumerId' - the consumer id	ConsumerInfo	false	advisoryForSlowConsumers
ActiveMQ.Advisory.FastProducer.Queue	Fast Queue producer	String='producerId' - the producer id	ProducerInfo	false	advisdoryForFastProducers
ActiveMQ.Advisory. FastProducer.Topic	Fast Topic producer	String='consumerId' - the producer id	ProducerInfo	false	advisdoryForFastProducers
ActiveMQ.Advisory.MessageDiscarded.Queue	Message discarded	String='orignalMessageId' - the discarded id	Message	false	advisoryForDiscardingMessages
ActiveMQ.Advisory.MessageDiscarded.Topic	Message discarded	String='orignalMessageId' - the discarded id	Message	false	advisoryForDiscardingMessages
ActiveMQ.Advisory.MessageDelivered.Queue	Message delivered to the broker	String='orignalMessageId' - the delivered id	Message	false	advisoryForDelivery
ActiveMQ.Advisory.MessageDelivered.Topic	Message delivered to the broker	String='orignalMessageId' - the delivered id	Message	false	advisoryForDelivery
ActiveMQ.Advisory.MessageConsumed.Queue	Message consumed by a client	String='orignalMessageId' - the delivered id	Message	false	advisoryForConsumed
ActiveMQ.Advisory.MessageConsumed.Topic	Message consumed by a client	String='orignalMessageId' - the delivered id	Message	false	advisoryForConsumed
ActiveMQ.Advisory.FULL	A Usage resource is at its limit	String='usageName' - the name of Usage resource	null	false	advisoryWhenFull
ActiveMQ.Advisory.MasterBroker	A broker is now the master in a master/slave configuration	null	null	true	none

从5.4版本新加的DLQ的通知消息

Advisory Topics	Description	properties	Data Structure	default	PolicyEntry property
ActiveMQ.Advisory.MessageDLQd.Queue	Message sent to DLQ	String='orignalMessageId' - the delivered id	Message	Always on	advisoryForConsumed
ActiveMQ.Advisory.MessageDLQd.Topic	Message sent to DLQ	String='orignalMessageId' - the delivered id	Message	Always on	advisoryForConsumed

从5.5版本新加的网络连接集群的通知消息

Advisory Topics	Description	properties	Data Structure	default
ActiveMQ.Advisory.NetworkBridge	Network bridge being stopped or started	Boolean="started" - true if bridge is started, false if it is stopped Boolean="createdByDuplex" - true if the bridge is created by remote network connector	BrokerInfo - provides data of the remote broker	Always on

打开通知消息开关的示例

<destinationPolicy>
   <policyMap><policyEntries> 
      <policyEntry topic=">" advisoryForConsumed="true" />
   </policyEntries></policyMap>
</destinationPolicy>

此外，在broker上有个通知消息的总开关，设置false以后，所有的Advisory都不可用：

 <broker advisorySupport="false">...