Spring Message Listener Container doc says:
http://static.springsource.org/spring/docs/2.5.x/api/org/springframework/jms/listener/AbstractMessageListenerContainer.html#setDurableSubscriptionName%28java.lang.String%29
The durable subscription name needs to be unique within this client's
JMS client id. Default is the class name of the specified message
listener. Note: Only 1 concurrent consumer (which is the default of
this message listener container) is allowed for each durable
subscription.
I thought, we can handle concurrent messages at the same time. Am I missing something?
Yes, the documentation is correct. At any point of time there can be only one consumer receiving messages for a durable subscription. All durable subscriptions are identified by a unique id. If one consumer is already receiving messages using an id, another attempt create a consumer with the same id for that durable subscription will fail.
I've had this problem before and our log was full of warnings complain about client id is already in use.
Virtual Topic is an option for ActiveMQ: the idea is similar to what #brainOverflow described, it's a combination of topic and queues. The producer sends the message to a topic which is subscribed by queues and each queue receives a copy of the message.
http://activemq.apache.org/virtual-destinations.html
Related
Is it possible to configure the topic to store a copy of just the last message and send this to new connections without knowing client identifiers or other info?
Update:
From the info provided by Shashi I found this two pages where they describe a use case similar to mine (applied over stock prices) by using retroactive consumer and a subscription recovery policy. How ever I'm not getting the desired behaviour. What I currently do is:
Include in the activemq the folowing lines in the policyEntry for topic=">"
<subscriptionRecoveryPolicy>
<fixedCountSubscriptionRecoveryPolicy maximumSize="1"/>
</subscriptionRecoveryPolicy>
Add to the URL used to connect to the brocker (using activemq-cpp) consumer.retroactive=true.
Set the consumer has durable. (But I strongly think this is not want since I only need the last one, but without it I didn't get any message when starting the consumer for the second time)
Start up the broker.
Start the consumer.
Send a message to the topic using the activemq web admin console. (I receive it in the consumer, as expected)
Stop consumer.
Send another message to the topic.
Start consumer. I receive the message, also as expected.
However, if the consumer receives a message, then it goes offline (stop process) and then I restart it, it doesn't get the last message back.
The goal is to whenever the consumer starts get the last message, no mater what (obviously, except when there weren't messages sent to the topic).
Any ideas on what I'm missing?
Background:
I have a device which publishes his data to a topic when ever its data changes. A variable number of consumer may be connected to this topic, from 0 to less than 10. There is only one publisher in the topic and always publish all of his data as a single message (little data, just a couple of fields of a sensor reading). The publication rate of this information is variable, not necessarily time based, when something changes a new updated message is sent to the broker.
The problem is that when a new consumer connects to the topic it has no data of the device readings until a new message is send to the topic by the device. This could be solve by creating an additional queue so new connections can subscribe to the topic and then request the device for the current reading through the queue (the device would consume the queue message which would be a request for data, and then response in the same queue).
But Since the messages send to the topic are always information complete I was wondering if is it possible to configure the topic to store a copy of just the last message and send this to new connections without know client identifiers or other info?
Current broker in use is ActiveMQ.
What you want is to have retroactive consumers and to set the lastImageSubscriptionRecoveryPolicy subscription recovery policy on the topic. Shashi is correct in saying that the following syntax for setting a consumer to be retroactive works only with Openwire
topic = new ActiveMQTopic("TEST.Topic?consumer.retroactive=true");
In your case, what you can do is to configure all consumers to be retroactive in broker config with alwaysRetroactive="true". I tested that this works even for the AMQP protocol (library qpid-jms-client) and I suspect it will work for all protocols.
<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry topic="FOO.>" alwaysRetroactive="true">
<subscriptionRecoveryPolicy>
<lastImageSubscriptionRecoveryPolicy />
</subscriptionRecoveryPolicy>
</policyEntry>
The configuration example is taken from https://github.com/apache/activemq/blob/master/activemq-unit-tests/src/test/resources/org/apache/activemq/test/retroactive/activemq-message-query.xml
Messaging providers (WebSphere MQ for example) have a feature called Retained Publication. With this feature the last published message on a topic is retained by the messaging provider and delivered to a new consumer who comes in after a message has been published on a given topic.
Retained Publication may be supported by Active MQ in it's native interface. This link talks about consumer.retroactive which is available for OpenWire only.
A publisher will tell the messaging provider to retain a publication by setting a property on the message before publishing. Below is how it is done using WebSphere MQ.
// set as a retained publication
msg.setIntProperty(JmsConstants.JMS_IBM_RETAIN, JmsConstants.RETAIN_PUBLICATION)
I am new to world of JMS and stuck in an issue. Here it is;
Suppose I have one topic and all the clients are publishing and subscribing to same topic. What i want to achieve is this if ClientA publishes a message to the topic then all the other clients should receive that message but ClientA (Sender should not receive his own message returned back).
You need to configure the subscriber to ignore messages published from the current connection.
This is done by setting the noLocal option when creating a subscriber.
See How can I prevent receiving JMS messages that I have produced?.
I'm trying to create new subscriber with 'Destination name' as local-queue-name, but for that I need non-durable subscriber.
When creating new subscriber in MQ, using MQSC or MQ-Explorer, how do I make it non-durable?
Is there any way to change it (alter) after it has been created?
Thanks.
Non-durable subscriptions are active as long as the application that created them is active. Once the application ends or application closes connection to queue manager, these subscriptions are removed. What this means is non-durable subscriptions can only be created programmatically using MQSUB(in C language) or it's equivalent method in Java/C#.
Non-durable subscriptions can not be created using MQSC or MQExplorer. You can create durable subscriptions using MQSC/MQExplorer.
Non-durable subscriptions exist only as long as the subscribing application's connection to the queue manager remains open. The subscription is removed when the subscribing application disconnects from the queue manager either deliberately or by loss of connection. When the connection is closed, the information about the subscription is removed from the queue manager, and will no longer be shown if you display subscriptions using the DISPLAY SBSTATUS command. No more messages will be put to the subscriber queue.
For more information, see Subscription durability
I am using ActiveMQ as a JMS implementation server in my application. Scenario is like, there is a topic over which I have many durable subscribers which consumes the published message and a message listener which save the data from message object to central DB server. There is a producer thread which keeps on publishing persistent message over the same topic. I am using KahaDB for persistent Message Store. As soon as a message is published, kahaDB creates a data log file in message store to persist message until all durable subscriber consume it. I want to know if at any point, I shutdown the JMS server and delete all the data log files, what would be the impact. Will it be just that few durable subscriers will not receive a message which was there in data log files for them to be consumed or is there a possibility that few message didn't got saved in central database which is done by message listener over this topic.
Any hint or help is greatly appreciated......
Thanks in advance.
If you stop and start your broker, regardless of whether you delete your data files or not, topic consumer that have not already received a published message will no longer receive it. The reason behind this is that messages sent to a topic will not be written out to the persistent message store.
Durability and persistence are not the same things. A durable subscription tells the broker to preserve the subscription state in case the subscriber disconnects - any messages sent while the consumer is disconnected will be kept around. A non-durable subscription on the other hand is finite; if a subscriber disconnects, it missed any messages sent in the interim. All messages are stored in memory, and will not survive a broker restart.
Message persistence on the other hand stores messages for eventual delivery. This guards against catastrophic failure, or for later delivery to consumers who might not yet be active.
If you want to broadcast messages using pub-sub, and have the subscriptions appear durable and survive broker restarts you should use virtual destinations instead of durable subscriptions.
No messages, persistent or non-persistent, will survive switching the broker off and deleting the data directory.
I'm dealing with a standalone MQ JMS application, our app need to "aware" that client already consumed the message producer put on the queue. Because client app is not responsible by us. So we cannot let them to write something like "msg.acknowledge();" thing on their side (msg.acknowledge() is not the right approach on my condition.). I search the history answer in the stackoverflow. Find following is quite the same what I want:
https://stackoverflow.com/questions/6521117/how-to-guarantee-delivery-of-the-message-in-jms
Do the JMS spec or the various implementations support delivery confirmation of messages?
My question is, is there any other way to archive this in the MQ API or JMS API? I need to do the coding only on the msg produce side, it is can be queue or topic.
Another question is in the JMS the acknowledge mode CLIENT_ACKNOWLEDGE, is that produce irrelevant? I always believe that this mode can block the application when call send() method until the client consume the message and call the msg.acknowledge(), but seems not like that. The produce just exit the app after message be delivered, and the message just store in the queue until client call the acknowledge(). Is that possible let the producer app hang there wait until the message be acknowledged by the client?
If my concept is not right, just correct me, thanks.
The main intention of message queuing is to decouple producer and consumer. Producer does not need to wait for the message to be consumed by the consumer, it can continue it's job. Ideally if producer needs to know if the message has been processed by consumer or not, it should wait for consumer to send a response message on another queue.
Message acknowledgement has nothing to do with producer. Message acknowledgement is the way a consumer tells the messaging provider to remove the message from a queue after the message has been delivered to an application.
There is auto acknowledge where the JMS providers (like MQ JMS), after delivering message to an application, tell the messaging provider to remove the message from queue. Then there is client acknowledge where, after receiving a message, the application explicitly tells the messaging provider to remove message from a queue.
Is there is a reason why the producer has to wait for consumer to receive the message? One way, though not elegant, could be: Once the message is sent, use the message id of the sent message and try to browse for that message. If message is not found, you can assume it has been consumed