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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.common.endpoints.listeners;
import java.util.concurrent.ConcurrentHashMap;
import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
import org.onap.policy.common.utils.coder.StandardCoderObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Dispatches standard objects to listeners, based on the message type extracted from the
* message. Only one listener may be registered for a given type.
*/
public class MessageTypeDispatcher extends JsonListener {
private static final Logger logger = LoggerFactory.getLogger(MessageTypeDispatcher.class);
/**
* Name of the message field, which may be hierarchical.
*/
private final String[] messageFieldNames;
/**
* Name of the message field, joined with "." - for logging.
*/
private final String fullMessageFieldName;
/**
* Maps a message type to its listener.
*/
private final ConcurrentHashMap<String, ScoListener<?>> type2listener = new ConcurrentHashMap<>();
/**
* Constructs the object.
*
* @param messageFieldNames name of the message field, which may be hierarchical
*/
public MessageTypeDispatcher(String... messageFieldNames) {
this.messageFieldNames = messageFieldNames;
this.fullMessageFieldName = String.join(".", messageFieldNames);
}
/**
* Registers a listener for a certain type of message.
*
* @param type type of message of interest to the listener
* @param listener listener to register
*/
public <T> void register(String type, ScoListener<T> listener) {
type2listener.put(type, listener);
}
/**
* Unregisters the listener associated with the specified message type.
*
* @param type type of message whose listener is to be unregistered
*/
public void unregister(String type) {
type2listener.remove(type);
}
@Override
public void onTopicEvent(CommInfrastructure infra, String topic, StandardCoderObject sco) {
// extract the message type
final String type = sco.getString(messageFieldNames);
if (type == null) {
logger.warn("unable to extract {}: {}", fullMessageFieldName, sco);
return;
}
// dispatch the message
ScoListener<?> listener = type2listener.get(type);
if (listener == null) {
logger.info("discarding event of type {}", type);
return;
}
listener.onTopicEvent(infra, topic, sco);
}
}
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