/*
* Copyright 2013 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.springframework.yarn.integration;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.integration.core.MessagingTemplate;
import org.springframework.integration.endpoint.EventDrivenConsumer;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageDeliveryException;
import org.springframework.messaging.MessageHandler;
import org.springframework.messaging.MessagingException;
import org.springframework.messaging.SubscribableChannel;
import org.springframework.util.Assert;
import org.springframework.yarn.am.AppmasterService;
import org.springframework.yarn.am.GenericRpcMessage;
import org.springframework.yarn.am.RpcMessage;
import org.springframework.yarn.integration.support.IntegrationObjectSupport;
import org.springframework.yarn.integration.support.PortExposingTcpSocketSupport;
/**
* Base implementation of {@link AppmasterService} using Spring Integration Ip
* channels as a communication link.
*
* @author Janne Valkealahti
*
*/
public abstract class IntegrationAppmasterService<T> extends IntegrationObjectSupport implements AppmasterService {
private static final Log log = LogFactory.getLog(IntegrationAppmasterService.class);
/** Interface needed to find info about the socket */
private PortExposingTcpSocketSupport socketSupport;
/** Channel where incoming messages are published */
private SubscribableChannel messageChannel;
/** Spring Int messaging template */
private final MessagingTemplate messagingTemplate;
/** Default message consumer if no custom configuration */
private EventDrivenConsumer consumer;
public IntegrationAppmasterService() {
messagingTemplate = new MessagingTemplate();
}
@Override
protected void doStart() {
consumer = new EventDrivenConsumer(messageChannel, new ReplyProducingHandler());
consumer.start();
}
@Override
protected void doStop() {
if(consumer != null) {
consumer.stop();
}
}
@Override
public int getPort() {
return socketSupport != null ? socketSupport.getServerSocketPort() : -1;
}
@Override
public String getHost() {
return socketSupport != null ? socketSupport.getServerSocketAddress() : null;
}
@Override
public boolean hasPort() {
return true;
}
/**
* Implementor need to write this method to process
* incoming messages.
*
* @param message the rpc message wrapping a protocol content
* @return a reply rpc message
*/
public abstract RpcMessage<T> handleMessageInternal(RpcMessage<T> message);
/**
* Sets the message channel where messages are dispatched.
*
* @param messageChannel the message channel
*/
public void setMessageChannel(SubscribableChannel messageChannel) {
Assert.notNull(messageChannel, "messageChannel must not be null");
this.messageChannel = messageChannel;
}
/**
* Sets the socket support for this service.
*
* @param socketSupport the socket support
*/
public void setSocketSupport(PortExposingTcpSocketSupport socketSupport) {
Assert.notNull(socketSupport, "socketSupport must not be null");
this.socketSupport = socketSupport;
if(log.isDebugEnabled()) {
log.debug("Setting socket support: " + socketSupport);
}
}
/**
* Send the message to the given channel. The channel must be a String or
* {@link MessageChannel} instance, never <code>null</code>.
*
* @param message the Spring Int message
* @param channel the channel to send to
*/
private void sendMessage(final Message<?> message, final Object channel) {
if (channel instanceof MessageChannel) {
this.messagingTemplate.send((MessageChannel) channel, message);
} else if (channel instanceof String) {
this.messagingTemplate.send((String) channel, message);
} else {
throw new MessageDeliveryException(message,
"a non-null reply channel value of type MessageChannel or String is required");
}
}
/**
* Internal default message handler which is used to handle
* wrapping of {@link RpcMessage} inside a {@link Message}.
* Gets the actual user facing message from a method and tries
* to provide reply to a reply channel. This handler is
* not necessarily used if user used custom configuration.
*/
private class ReplyProducingHandler implements MessageHandler {
@SuppressWarnings("unchecked")
@Override
public void handleMessage(Message<?> message) throws MessagingException {
GenericRpcMessage<T> incoming = new GenericRpcMessage<T>((T) message.getPayload());
RpcMessage<T> outgoing = handleMessageInternal(incoming);
Message<?> reply = MessageBuilder.withPayload(outgoing.getBody()).build();
sendMessage(reply, message.getHeaders().getReplyChannel());
}
}
}