...
Code Block |
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SimpleRegistry registry = new SimpleRegistry();
EventBus eventBus = new EventBus();
registry.put("busName", eventBus);
CamelContext camel = new DefaultCamelContext(registry);
from("direct:start").to("guava-eventbus:busName");
ProducerTemplate producerTemplate = camel.createProducerTemplate();
producer.sendBody("direct:start", "Send me to the Guava EventBus.");
eventBus.register(new Object(){
@Subscribe
public void messageHander(String message) {
System.out.println("Message received from the Camel: " + message);
}
});
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DeadEvent considerations
Keep in mind that due to the limitations caused by the design of the Guava EventBus, you cannot specify event class to be received by the listener without creating class annotated with @Subscribe
method. This limitation implies that endpoint with eventClass
option specified actually listens to all possible events (java.lang.Object
) and filter appropriate messages programmatically at runtime. The snipped below demonstrates an appropriate excerpt from the Camel code base.
Code Block |
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@Subscribe
public void eventReceived(Object event) {
if (eventClass == null || eventClass.isAssignableFrom(event.getClass())) {
doEventReceived(event);
...
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This drawback of this approach is that EventBus
instance used by Camel will never generate com.google.common.eventbus.DeadEvent
notifications. If you want Camel to listen only to the precisely specified event (and therefore enable DeadEvent
support), use listenerInterface
endpoint option. Camel will create dynamic proxy over the interface you specify with the latter option and listen only to messages specified by the interface handler methods. The example of the listener interface with single method handling only SpecificEvent
instances is demonstrated below.
Code Block |
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package com.example;
public interface CustomListener {
@Subscribe
void eventReceived(SpecificEvent event);
}
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The listener presented above could be used in the endpoint definition as follows.
Code Block |
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from("guava-eventbus:busName?listenerInterface=com.example.CustomListener").to("seda:queue");
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