/*
* Copyright 2010 The Fornax Project Team, including the original
* author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.sculptor.framework.event;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.Resource;
import org.apache.camel.CamelContext;
import org.apache.camel.Consumer;
import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.ProducerTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class CamelEventBusImpl implements EventBus {
private static final String DEFAULT_TOPIC_PREFIX = "direct:";
private final Logger log = LoggerFactory.getLogger(getClass());
private final Map<EventListener, Consumer> listeners = new HashMap<EventListener, Consumer>();
@Resource(name = "producerTemplate")
private ProducerTemplate producer;
@Autowired
private CamelContext camelContext;
private final boolean propagateException;
public CamelEventBusImpl() {
this.propagateException = false;
}
public CamelEventBusImpl(boolean propagateException) {
this.propagateException = propagateException;
}
public boolean publish(String toTopic, Event event) {
try {
producer.sendBody(prefixed(toTopic), event);
return true;
} catch (RuntimeException e) {
if (propagateException) {
throw e;
} else {
log.warn(String.format("Exception when publishing event %s to topic %s", event, toTopic));
}
return false;
}
}
public boolean subscribe(String toTopic, final EventSubscriber subscriber) {
try {
Endpoint endpoint = camelContext.getEndpoint(prefixed(toTopic));
Consumer consumer = endpoint.createConsumer(new org.apache.camel.Processor() {
public void process(Exchange exchange) throws Exception {
Event event = (Event) exchange.getIn().getBody();
subscriber.receive(event);
}
});
camelContext.addService(consumer);
synchronized (listeners) {
listeners.put(new EventListener(toTopic, subscriber), consumer);
}
} catch (RuntimeException e) {
throw e;
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
return true;
}
public boolean unsubscribe(String toTopic, EventSubscriber subscriber) {
try {
EventListener eventListener = new EventListener(toTopic, subscriber);
Consumer consumer = null;
synchronized (listeners) {
consumer = listeners.get(eventListener);
listeners.remove(eventListener);
}
if (consumer != null) {
consumer.stop();
}
} catch (RuntimeException e) {
throw e;
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
return true;
}
protected String prefixed(String topic) {
if (topic.contains(":")) {
return topic;
} else {
return DEFAULT_TOPIC_PREFIX + topic;
}
}
}