Connecting to two machines from spring AMQP

[avyaktha]

I have a situation where i need to connect to two hosts. I setup two separate configuration classes , with different connections and queue declarations and bindings.

have

<context:component-scan base-package="com.xx.tdb.queue_processor.config1,com.xx x.tdb.queue_processor.config2"/>

entry in my spring config file. AMQP always seems to load and initialize only one of the config classes.None of the auto wiring init is happening in the other config class. what am i doing wrong?


Thanks in advance,
Suresh

[Mark Fisher]

Are you providing distinct bean names for the results of your @Bean-annotated methods?

[avyaktha]

u mean methods like

@Bean
public Queue eventQueue() {
return new Queue(queueName);
}

@Bean
public DirectExchange tdbExchange() {
return new DirectExchange(exchangeName);
}

/**
* Binds to the TDB data exchange. Interested in any events.
* @return binding object
*/
@Bean
public Binding tdbDataBinding() {
return BindingBuilder.from(
eventQueue()).to(tdbExchange()).with(routingKey);
}



shd these be distinct ?

[avyaktha]

Dumb , got it

thanks for your help

[Mark Fisher]

Have you verified that and got it working correctly now?

I should have explained it in a bit more detail...

The method names become bean names, and the behavior is similar to the use of bean IDs within XML files. They must be unique within a single ApplicationContext so if there is overlap, the last bean definition registered will replace any existing bean with the same ID/name.

Hope that helps.
-Mark

[avyaktha]

Thanks Mark, yeah got that.

Still facing an issue, I have two consumers connecting to two hosts.
host1 and host2, I have two java config classes RabbitMqConfiguration1 and RabbitMqConfiguration2. The only difference is they both connect to a different host. When i try to start the listeners , I keep getting a queue not declared error in one of them. When i debug i do see both the bindings getting registered to the correct hosts in both the config classes.

the error i get is as follows

Caused by: com.rabbitmq.client.ShutdownSignalException: channel error; reason: {#method<channel.close>(reply-code=404,reply-text=NOT_FOUND - no queue 'LWESEvents' in vhost 'TDB-Dev',class-id=50,method-id=10),null,""}



when I start them by pointing them to the same host, either 1 or 2 then it works.

@Bean(name = "eventQueue2")
public Queue eventQueue() {

}

@Bean(name = "tdbExchange2")
public DirectExchange tdbExchange() {
}

@Bean(name = "tdbDataBinding2")
public Binding tdbDataBinding() {
}

@Bean(name = "messageListenerContainer2")
public SimpleMessageListenerContainer messageListenerContainer() {
}

@Bean(name = "connectionFactory2")
public ConnectionFactory connectionFactory() {
//only host differs here rest of all the params are same
}

@Bean(name = "messageListenerAdapter2")
public MessageListenerAdapter messageListenerAdapter() {
}

thanks again for your help
Suresh

[avyaktha]

Ahh!! its cause the amqpAdmin was a singleton.

I fixed it by not implementing from AbstractRabbitConfiguration and providing my own adminbean

@Bean(name = "amqpAdmin1")
public AmqpAdmin amqpAdmin() {
return new RabbitAdmin(rabbitTemplate());
}

@Bean(name = "template1")
public RabbitTemplate rabbitTemplate() {
return new RabbitTemplate(connectionFactory());
}

Is there a better way to do this, I see that the BIndings are registered for each of the admins twice, its ok in my case as everything except the host is the same.

thanks,
Suresh

[avyaktha]

any one , have any suggestions?

[Mark Pollack]

Hi,

We should more explicitly support this type of scenario. What I can suggest is to either set autoStartup to false in RabbitAdmin or avoid its use completely so that it doesn't perform any of the declarations and instead do it yourself in code. Not ideal. Perhaps a better short term approach is to subclass RabbitAdmin and override the start method so that only the Exchange,Queues, and Bindings specific to a given broker/connection will be used. Instead of the current code that get all the queues, i.e.

applicationContext.getBeansOfType(Queue.class).values();

It would instead use a lookup method that uses qualifier annotations to restrict the set of returned beans.

getBeansWithAnnotation(Class<? extends Annotation> annotationType)

comes close but one would also like to specify the class... a getBeanOfTypeWithAnnotation method.... Otherwise you will have to filter out from the returned map the beans which are queues, exchanges, bindings...

The @Configuration bean definitons would then have the qualifier annotation on them.

@Bean(name = "eventQueue2")
@Qualifier("broker2")
public Queue eventQueue() {
}

I don't think there is 'inheritance' of qualifier annotations on the @Configuration class to the methods, but that might be nice to consider.

Then one would need two instances of this subclass of RabbitAdmin, each configured to use different qualifier annotations.

HTH,
Mark

[Dave Syer]

Maybe two ApplicationContext instances, one for each host would help?

Multiple vhosts is something we should support eventually (and Holly said she was interested in contributing in this area), so it will be useful to keep this discussion going. Open a JIRA or two maybe?