TopicMessageChannel.java

/*
 * Copyright 2013-2014 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.cloud.aws.messaging.core;

import com.amazonaws.services.sns.AmazonSNS;
import com.amazonaws.services.sns.model.MessageAttributeValue;
import com.amazonaws.services.sns.model.PublishRequest;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.support.AbstractMessageChannel;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.NumberUtils;

import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;

/**
 * @author Agim Emruli
 * @author Alain Sahli
 * @since 1.0
 */
public class TopicMessageChannel extends AbstractMessageChannel {

    public static final String NOTIFICATION_SUBJECT_HEADER = "NOTIFICATION_SUBJECT_HEADER";

    private final AmazonSNS amazonSns;
    private final String topicArn;

    public TopicMessageChannel(AmazonSNS amazonSns, String topicArn) {
        this.amazonSns = amazonSns;
        this.topicArn = topicArn;
    }

    @Override
    protected boolean sendInternal(Message<?> message, long timeout) {
        PublishRequest publishRequest = new PublishRequest(this.topicArn, message.getPayload().toString(), findNotificationSubject(message));
        Map<String, MessageAttributeValue> messageAttributes = getMessageAttributes(message);
        if (!messageAttributes.isEmpty()) {
            publishRequest.withMessageAttributes(messageAttributes);
        }
        this.amazonSns.publish(publishRequest);

        return true;
    }

    private static String findNotificationSubject(Message<?> message) {
        return message.getHeaders().containsKey(NOTIFICATION_SUBJECT_HEADER) ? message.getHeaders().get(NOTIFICATION_SUBJECT_HEADER).toString() : null;
    }

    private Map<String, MessageAttributeValue> getMessageAttributes(Message<?> message) {
        HashMap<String, MessageAttributeValue> messageAttributes = new HashMap<>();
        for (Map.Entry<String, Object> messageHeader : message.getHeaders().entrySet()) {
            String messageHeaderName = messageHeader.getKey();
            Object messageHeaderValue = messageHeader.getValue();

            if (MessageHeaders.CONTENT_TYPE.equals(messageHeaderName) && messageHeaderValue != null) {
                messageAttributes.put(messageHeaderName, getContentTypeMessageAttribute(messageHeaderValue));
            } else if (MessageHeaders.ID.equals(messageHeaderName) && messageHeaderValue != null) {
                messageAttributes.put(messageHeaderName, getStringMessageAttribute(messageHeaderValue.toString()));
            } else if (messageHeaderValue instanceof String) {
                messageAttributes.put(messageHeaderName, getStringMessageAttribute((String) messageHeaderValue));
            } else if (messageHeaderValue instanceof Number) {
                messageAttributes.put(messageHeaderName, getNumberMessageAttribute(messageHeaderValue));
            } else if (messageHeaderValue instanceof ByteBuffer) {
                messageAttributes.put(messageHeaderName, getBinaryMessageAttribute((ByteBuffer) messageHeaderValue));
            } else {
                this.logger.warn(String.format("Message header with name '%s' and type '%s' cannot be sent as" +
                                " message attribute because it is not supported by SNS.", messageHeaderName,
                        messageHeaderValue != null ? messageHeaderValue.getClass().getName() : ""));
            }
        }

        return messageAttributes;
    }

    private MessageAttributeValue getBinaryMessageAttribute(ByteBuffer messageHeaderValue) {
        return new MessageAttributeValue().withDataType(MessageAttributeDataTypes.BINARY).withBinaryValue(messageHeaderValue);
    }

    private MessageAttributeValue getContentTypeMessageAttribute(Object messageHeaderValue) {
        if (messageHeaderValue instanceof MimeType) {
            return new MessageAttributeValue().withDataType(MessageAttributeDataTypes.STRING).withStringValue(messageHeaderValue.toString());
        } else if (messageHeaderValue instanceof String) {
            return new MessageAttributeValue().withDataType(MessageAttributeDataTypes.STRING).withStringValue((String) messageHeaderValue);
        }
        return null;
    }

    private MessageAttributeValue getStringMessageAttribute(String messageHeaderValue) {
        return new MessageAttributeValue().withDataType(MessageAttributeDataTypes.STRING).withStringValue(messageHeaderValue);
    }

    private MessageAttributeValue getNumberMessageAttribute(Object messageHeaderValue) {
        Assert.isTrue(NumberUtils.STANDARD_NUMBER_TYPES.contains(messageHeaderValue.getClass()), "Only standard number types are accepted as message header.");

        return new MessageAttributeValue().withDataType(MessageAttributeDataTypes.NUMBER + "." + messageHeaderValue.getClass().getName()).withStringValue(messageHeaderValue.toString());
    }
}