Message.java

/**
 * Copyright 2016 Yahoo Inc.
 *
 * 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 com.yahoo.pulsar.client.api;

import java.util.Map;

/**
 * The message abstraction used in Pulsar.
 *
 *
 */
public interface Message {

    /**
     * Return the properties attached to the message.
     *
     * Properties are application defined key/value pairs that will be attached to the message
     *
     * @return an unmodifiable view of the properties map
     */
    Map<String, String> getProperties();

    /**
     * Check whether the message has a specific property attached.
     *
     * @param name
     *            the name of the property to check
     * @return true if the message has the specified property
     * @return false if the properties is not defined
     */
    boolean hasProperty(String name);

    /**
     * Get the value of a specific property
     *
     * @param name
     *            the name of the property
     * @return the value of the property or null if the property was not defined
     */
    String getProperty(String name);

    /**
     * Get the content of the message
     *
     * @return the byte array with the message payload
     */
    byte[] getData();

    /**
     * Get the unique message ID associated with this message.
     *
     * The message id can be used to univocally refer to a message without having the keep the entire payload in memory.
     *
     * Only messages received from the consumer will have a message id assigned.
     *
     * @return the message id null if this message was not received by this client instance
     */
    MessageId getMessageId();

    long getPublishTime();

    /**
     * Check whether the message has a key
     *
     * @return true if the key was set while creating the message
     * @return false if the key was not set while creating the message
     */
    boolean hasKey();

    /**
     * Get the key of the message
     *
     * @return the key of the message
     */
    String getKey();
}