We have followed the instructions in http://www.rabbitmq.com/ha.html to setup an active-active cluster with 3 nodes rabbit1, rabbit2 and rabbit3.
To create a mirrored queue, we are using x-ha-policy and to get consumer cancellation notifications we have put true for consumer_cancel_notify in clientProperties.
Now, we published messages to the queue with rabbit2 as master and had the consumer consume from rabbit3. When rabbit2 is stopped, the consumer connected to rabbit3 is not getting a cancellation notification.
We are using rabbitmq 2.8.2-1 and our java consumer POC code is here - https://gist.github.com/2990146
Not sure what we are doing wrong. Any pointers would be highly appreciated.
Has anyone attempted to handle cancel notifications with php-amqplib?
Line #22 of your gist is a problem. consumer_cancel_notify needs to be in the capabilities table in clientProperties rather than a top-level key.
clientProperties.put("consumer_cancel_notify", Boolean.valueOf(true));
AMQP 0-9-1 clients don't by default expect to receive basic.cancel
methods from the broker asynchronously, and so in order to enable this
behaviour, the client must present a capabilities table in its
client-properties in which there is a key consumer_cancel_notify and a
boolean value true. See the capabilities section for further details
on this.
http://www.rabbitmq.com/extensions.html#consumer-cancel-notify
Handwaving pseudo-java (please edit this answer after testing)
Map<String, Object> clientProperties = new HashMap<String, Object>();
Map<String, Object> clientCapabilities = new HashMap<String, Object>();
clientCapabilities.put("consumer_cancel_notify", Boolean.valueOf(true));
clientProperties.put("capabilities", clientCapabilities);
As for your original question, "Has anyone attempted to handle cancel notifications with php-amqplib?" it looks like the answer is a firm "maybe" ==>
http://grokbase.com/t/rabbitmq/rabbitmq-discuss/11cynv8zkz/active-active-implementation-in-php
Related
This document https://www.rabbitmq.com/reliability.html says it is possible to achieve at-least-once guarantee with RabbitMQ without using transactions. The problem with transactions is that they are slow, so the throughput drops drastically (see sections Publisher Confirms in https://www.rabbitmq.com/confirms.html). The option is to use Consumer Acknowledgements and Publisher Confirms.
On the other hand, Spring AMQP is able to handle Consumer Acknowledgements automatically using this configuration:
spring.rabbitmq.listener.acknowledgeMode=AUTO
For Publisher Confirms this is the configuration:
spring.rabbitmq.publisherConfirms=true
My doubt is whether these two properties are enough to guarantee at-least-once delivery or if I need to do anything else.
You will need to add a confirm callback to the rabbit template (either a custom one or the one configured by boot) to get the confirmations. You can add correlation data to the message sends so that you can correlate the confirm with the send.
See the documentation.
For Publisher Confirms (aka Publisher Acknowledgements), the template requires a CachingConnectionFactory that has its publisherConfirms property set to true. Confirms are sent to to the client by it registering a RabbitTemplate.ConfirmCallback by calling setConfirmCallback(ConfirmCallback callback). The callback must implement this method:
void confirm(CorrelationData correlationData, boolean ack, String cause);
The CorrelationData is an object supplied by the client when sending the original message. The ack is true for an ack and false for a nack. For nack s, the cause may contain a reason for the nack, if it is available when the nack is generated. An example is when sending a message to a non-existent exchange. In that case the broker closes the channel; the reason for the closure is included in the cause. cause was added in version 1.4.
Only one ConfirmCallback is supported by a RabbitTemplate.
I am trying to connect from my Android app to one queue called "messages".
The producer (one webservices under AMQP protocol) is already connected, it can be check through RabbitMQ admin panel.
To connect from my Android device I am coding like this.
private void connect() throws Exception {
this.sampleClient = new MqttClient(this.broker, this.clientId);
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setUserName("user");
connOpts.setPassword("user".toCharArray());
/*connOpts.setConnectionTimeout(60 * 10);
connOpts.setKeepAliveInterval(60 * 5);*/
connOpts.setCleanSession(true);
this.sampleClient.connect(connOpts);
this.sampleClient.setCallback(this);
this.sampleClient.subscribe("messages");
if(!this.sampleClient.isConnected()){
System.out.println("Not Connected");
return;
}
System.out.println("Connected");
}
I have tried with "amq.topic", "amq.topic.*", "amq.topic.messages", etc... But when I look in the RabbitMQ queue section "messages" is with 0 consumers, and have been set one new queue called "mqtt-subscription-Sampleqos1" automatically.
What's happening? How can I susbscribe to "messages" queue?
There are two important points about this question.
According with the RabbitMQ MQTT documentation: http://www.rabbitmq.com/mqtt.html
Firstly, every queues are bound automatically to amq.topic exchange by the mqtt-plugin.
Secondly, every subscriber has his own queue which look like this, mqtt-subscription-{cliend_id}{qosX} (where X is the qos level of the subscription)
Therefore, producer must to publish the message to "amq.topic" exchange, and "amq.topic.." routing-key, and receiver must to subscribe to "amq.topic.." routing-key.
First, make sure MQTT plugin is enabled: rabbitmq-plugins enable rabbitmq_mqtt
From the client side (here is you Android app), you need subscriber to a topic, lets say, topic my/android/app/messages
this.sampleClient.subscribe("my/android/app/messages");
Then, from the server side, because of RabbitMQ's implementation, you need send the message to a special exchange 'amq.topic' with appropriate route key my.android.app.messages (notice the mapping between '/' and '.', MQTT use / and AMQP use .). For example if you publish by pika AMQP Python lib, the code will looks like following:
channel.basic_publish(
exchange='amq.topic',
routing_key='my.android.app.messages',
body='hello world'
)
In your case, you want to receive message from queue "messages", basically there is no way to directly subscriber message from that AMQP queue on your MQTT client. The work around is create a service running on your server side, work as AMQP subscriber, receive message from "messages" queue, and transparent forward message to exchange amq.topic with proper routing key.
Hope my answer helpful.
We are facing a random issue with ActiveMQ and its consumers. We observe that, few consumers are not receiving messages, even though they are connected to ActiveMQ queue. But it works fine after the consumer restart.
We have a queue named testQueue at ActiveMQ side. A consumer is trying to de-queue the messages from this queue. We are using Spring's DefaultMessageListenerContainer for this purpose. Message is being delivered to the consumer node from ActiveMQ Broker. From the tcpdump as well, it was obvious that, message is reaching the consumer node, But the actual consumer code is not able to see the message. In other words, the message seems to be stuck either in ActiveMQ consumer code or in Spring’s DefaultMessageListenerContainer.
See refer to the below fig. for more clarity on the issue. Message is reaching Consumer node, but it is not reaching the “Actual Consumer Class”, which means that the message got stuck either in AMQ consumer code or Spring DMLC.
Below are the details captured from ActiveMQ admin.
Queue-Name /Pending-Message-Count /Consumer-Count /Messages-Enqueued /Messages-Dequeued
testQueue /9 /1 /9 /0
Below are the more details.
Connection-ID /SessionId /Selector /Enqueues /Dequeues /Dispatched /Dispatched-Queue /Prefetch
ID:bearsvir52-45176-1375519181268-3:5 /1 / /9 /0 /9 /9 /250
From the second table it is obvious that, messages are being delivered to the consumer, but the consumer is not acknowledging the message. Hence the messages are stuck in Dispatched-Queue at broker side.
Few points for to your notice:
1)There is no time difference b/w Broker node and consumer node.
2)Observed the tcpdump at consumer side. We can see MessageDispatch(Openwire) packet being transferred to consumer node, But could not find the MessageAck(Openwire) for the same.
3)Sometimes it is working on a node, and sometimes it is creating problem on the same node.
One cause of this can be incorrectly using a CachingConnectionFactory (with cached consumers) with a listener container that dynamically adjusts the consumers (max consumers > consumers). You can end up with a cached consumer just sitting in the pool and not being actively used. You never need to cache consumers with a listener container.
For problems like this, I generally recommend running with TRACE logging and you can see all the consumer activity.
It took lot of time to figure out the solution. There seems to be some issue with the org.apache.activemq.ActiveMQConnection.java class, in case of AMQ fail over. The connection object is not getting started at consumer side in such cases.
Following is the fix i have added in ActiveMQConnection.java file and compiled the sources to create activemq-core-x.x.x.jar
private final Object startMutex = new Object();
added a check in createSession method
public Session createSession(boolean transacted, int acknowledgeMode) throws JMSException {
synchronized (startMutex) {
if(!isStarted()) {
start();
}
}
my existing code which uses BlockingQueue creates a list of BlockingQueue (like private List> queues;) in which I can put messages to process.
However due to persistence issue we plan to shift to activemq.
Can anyone please help me if we can get a list of activemq queue (in java program not from configuration file). I know that I can use createQueue on session to create a single instance of the queue but I want list of queue like done for BlockingQueue.
Any help would be much appreciated.
You can get a list of the available queues using DestinationSource from your connection.
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://localhost:61616");
ActiveMQConnection connection = (ActiveMQConnection)connectionFactory.createConnection();
DestinationSource ds = connection.getDestinationSource();
Set<ActiveMQQueue> queues = ds.getQueues();
edit:
to create a queue take a look at ActiveMQ Hello world sample link What the code does there is creating a connection to an activeMQ-broker embedded in the jvm
// Create a ConnectionFactory
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://localhost");
// Create a Connection
Connection connection = connectionFactory.createConnection();
connection.start();
// Create a Session
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
// Create the destination (Topic or Queue)
Destination destination = session.createQueue("TEST.FOO");
The thing that might not be obvious with above code is that the line:
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://localhost");
will not only setup a connection to a broker, but embedded a broker inside the connection if there isn't one already. Explained at the bottom of this page
That feature can be turned of using (you need a broker, but if you want to set it up in other way):
ActiveMQConnectionFactory cf = new ActiveMQConnectionFactory("vm://localhost?create=false");
I really like ActiveMQ, but it offers a lot more than persistence, so things might seem a little overly complex when doing the simple things. But hope that will not scare you.
To create a list of queues, you have to create that list, then create each queue individually from the session object.
Queue q = session.createQueue("someQueueName")
This, however, does not really "create" a queue in that sense, since a queue is a persistent "thing" in the ActiveMQ process/server. This will only create a reference to an ActiveMQ queue given an identifier/name.
I'm not sure why you need ten queues right up. Typically, you have one queue per event type or use case (or similar), then use concurrent consumers to process in parallel.
But of course, you can always do somethings similar by a simple for loop, creating one queue at a time and attaching them to an arraylist. Note that you cannot get type safe queues with only Event objects in them.
You can send ObjectMessages with events though. Just create one:
Event event = createEvent(..); // Given "Event" is serializable (need to be able to persist it).
Message m = session.createObjectMessage(event);
// Send message as usual in ActiveMQ.
It might be that you need to rethink one or a few things in your code when converting from BlockingQueues to persistent ActiveMQ queues.
For some reason I can not post to the masstransit google group, even though I joined, I am told that I do not have permission to post to this group. So I am going to post here...
Now for my problem:
I am using MassTransit v2.7.2, with AutoFac v2.6.3. I am trying to configure Autofac to scan an assembly and register my consumers; all types that implement the IConsumer interface. This seems to work.
I am using the MassTransit.AutofacIntegration assembly and the LoadFrom(...) extension method to register the consumers from the container with MassTransit when I configure the bus. Here is the code:
var builder = new ContainerBuilder();
builder
.RegisterAssemblyTypes(typeof (CreateElectionCommandHandler).Assembly)
.Where(type => type.Implements<IConsumer>())
.AsSelf();
var container = builder.Build();
var localBus = ServiceBusFactory.New(configurator =>
{
//configurator.ReceiveFrom("loopback://localhost/testqueue");
configurator.ReceiveFrom("rabbitmq://localhost/commandqueue");
configurator.UseRabbitMq();
configurator.Subscribe(sbc => sbc.LoadFrom(container));
});
Assert.IsTrue(container.IsRegistered<CreateElectionCommandHandler>());
Assert.IsTrue(container.IsRegistered<TerminateElectionCommandHandler>());
Assert.AreEqual(1, localBus.HasSubscription<CreateElection>().Count());
Assert.AreEqual(1, localBus.HasSubscription<TerminateElection>().Count());
If I run the above code using the loopback
configurator.ReceiveFrom("loopback://localhost/testqueue");
configuration (comment out the rabbitmq conifig), the test will pass.
If I comment out the "loopback" config and comment in the
configurator.ReceiveFrom("rabbitmq://localhost/commandqueue");
configurator.UseRabbitMq();
config, the test will fail. (Note: The rabbitmq queue is already up and running - I have been using it as part of my POC). Specifically, it will fail on the assertion:
Assert.AreEqual(1, localBus.HasSubscription<CreateElection>().Count());
Assert.AreEqual(1, localBus.HasSubscription<TerminateElection>().Count());
Can anybody help me understand what is going on here? I am new to MT so fully anticipating that I am missing something, or not configuring something correctly.
Am I correct to assume that if there are no message subscriptions registered, then the bus will not be able to deliver to any of my consumers (even though the consumers are registered)?
Any help much appreciated!
With RabbitMQ, subscriptions are not added to the outbound bus until a message is published. This is due to how the classes are inspected and outbound endpoints to the appropriate exchanges are created and added to the pipeline.
So yes, this test will fail with RabbitMQ, but it will in fact work properly when the message is published.
The HasSubscription() calls are really meant for verifying that consumers and such are properly configured using the loopback transport, and really just for vetting out things that are not really integration issues but just making sure the internal MassTransit code is working.
So, if you were to add a Publish() call of one of those types, and then call the HasSubscription() extension method, it would pass.
I would check to see if MassTransit creates an exchange the message types in question. Messages are sent to the exchange and all consumer queues are bound to the exchange. You can look at the Rabbit config to see if that's happened or not as well. And with no consumers registered, no messages will be delivered. Chris has been working on adding options to error is there's consumers so you can handle it in your code.
I would join the mailing list https://groups.google.com/forum/?fromgroups=#!forum/masstransit-discuss to get help. There's a lot more people that can ask the right questions to get you where you need to be.