Apache ActiveMQ ™ -- Advisory Message
Features > Message Features > Advisory Message
ActiveMQ supports advisory messages which allows you to watch the system using regular JMS messages. Currently we have advisory messages that support:
- consumers, producers and connections starting and stopping
- temporary destinations being created and destroyed
- messages expiring on topics and queues
- brokers sending messages to destinations with no consumers.
- connections starting and stopping
Advisory messages can be thought as some kind of administrative channel where you receive information regarding what is happening on your JMS provider along with what's happening with producers, consumers and destinations. When you look at a broker via JMX you will see the advisory topics prefixed with ActiveMQ.Advisory..
Every Advisory has the message type 'Advisory' and some predefined message properties:
Property
Type
Description
Version
originBrokerId
StringProperty
The id of the broker where the advisory originated.
5.x
originBrokerName
StringProperty
The name of the broker where the advisory originated.
5.x
originBrokerURL
StringProperty
The first URL of the broker where the advisory originated.
5.2
In addition, some messages carry a Command object, which carries additional information about the nature of the advisory, e.g., a subscription to each of the destination returns an ActiveMQMessage. Specific DataStructure objects, e.g.,. ConsumerInfo, ProducerInfo, ConnectionInfo can be retrieved using ActiveMQMessage.getDataStructure().
For example:
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); } } }
The following advisory topics are supported
Client based advisories
Tip
These are always generated.
Advisory Topics
Description
Properties
Data Structure
ActiveMQ.Advisory.Connection
Connection start & stop messages.
ConnectionInfo, RemoveInfo
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
ConnectionInfo, RemoveInfo
ActiveMQ.Advisory.Consumer.Topic
Consumer start & stop messages on a Topic.
String='consumerCount' - the number of Consumers
ConnectionInfo, RemoveInfo
Note that the consumer start/stop advisory messages also have a consumerCount header to indicate the number of active consumers on the destination when the advisory message was sent. This means you can use the following selector to be notified when there are no active consumers on a given destination:
consumerCount = 0
Destination and Message based advisories
Advisory Topics
Description
Properties
Data Structure
Default
PolicyEntry Property
ActiveMQ.Advisory.Queue
Queue create & destroy.
null
DestinationInfo
true
none
ActiveMQ.Advisory.Topic
Topic create & destroy.
null
DestinationInfo
true
none
ActiveMQ.Advisory.TempQueue
Temporary Queue create & destroy.
null
DestinationInfo
true
none
ActiveMQ.Advisory.TempTopic
Temporary Topic create & destroy.
null
DestinationInfo
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
Tip
NoConsumer topic advisories are sent only for non-persistent messages.
New advisories in version 5.2
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
New Advisories in 5.4
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
Network bridge advisories
Starting with ActiveMQ version 5.5 you can watch advisory topics for events related to the status of network bridges. You can get advisory messages when the network bridge is started or stopped.
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
Enabling Advisories Disabled by Default
The advisories that are not turned on by default (see the last column) can be enabled on a PolicyEntry in the ActiveMQ Broker Configuration, e.g., to enable a message consumed advisory you can configure the following:
Hint
The > character matches all topics - you can use wild-card matches for setting a destination policy - see Wildcards
Disabling Advisory Messages
The use of advisory messages incurs a small overhead in terms of memory and connection resources that is related to the number of destinations in your system. In some cases it can make sense to disable all advisories.
Advisories need to be disabled both on the Broker, via XML Configuration
or from java code:
BrokerService broker = new BrokerService(); broker.setAdvisorySupport(false); // ... broker.start();
and on your ActiveMQConnectionFactory (because a subscription to an advisory topic will auto create it) via the brokerUrl:
tcp://localhost:61616?jms.watchTopicAdvisories=false
or via java code using the watchTopicAdvisories attribute on the ActiveMQConnectionFactory.
ActiveMQConnectionFactory factory = new ActiveMQConnectionFactory(); factory.setWatchTopicAdvisories(false);
Warning
Advisory messages are required for dynamic network broker topologies as NetworkConnectors subscribe to advisory messages. In the absence of advisories, a network must be statically configured.
Using the Destinations
All of the above destinations are really prefixes which are appended with important information (like the actual topic or queue, the client ID, producer ID, consumer ID etc). This allows you to reuse the power of publish/subscribe, Wildcards and Selectors to filter the advisory messages as you see fit.
For example if you want to subscribe to expired messages on a topic FOO.BAR you could subscribe to ActiveMQ.Advisory.Expired.Topic.FOO.BAR. To subscribe to all messages of a certain kind of advisory just append .> to the topic, e.g., to subscribe to all the consumers starting and stopping to topics and queues subscribe to ActiveMQ.Advisory.Consumer..>.
Helper Methods
Methods to get the advisory destination objects are available in AdvisorySupport through the following methods.
AdvisorySupport.getConsumerAdvisoryTopic() AdvisorySupport.getProducerAdvisoryTopic() AdvisorySupport.getExpiredTopicMessageAdvisoryTopic() AdvisorySupport.getExpiredQueueMessageAdvisoryTopic() AdvisorySupport.getNoTopicConsumersAdvisoryTopic() AdvisorySupport.getNoQueueConsumersAdvisoryTopic() AdvisorySupport.getDestinationAdvisoryTopic() AdvisorySupport.getExpiredQueueMessageAdvisoryTopic() AdvisorySupport.getExpiredTopicMessageAdvisoryTopic() AdvisorySupport.getNoQueueConsumersAdvisoryTopic() AdvisorySupport.getNoTopicConsumersAdvisoryTopic()
// Version 5.2 on:
AdvisorySupport.getSlowConsumerAdvisoryTopic() AdvisorySupport.getFastProducerAdvisoryTopic() AdvisorySupport.getMessageDiscardedAdvisoryTopic() AdvisorySupport.getMessageDeliveredAdvisoryTopic() AdvisorySupport.getMessageConsumedAdvisoryTopic() AdvisorySupport.getMasterBrokerAdvisoryTopic() AdvisorySupport.getFullAdvisoryTopic()
Some helper classes to deal with advisory messages are available in the advisories package.