/*
* Copyright 2002-2016 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.integration.store;
import java.util.UUID;
import org.springframework.jmx.export.annotation.ManagedAttribute;
import org.springframework.messaging.Message;
/**
* Strategy interface for storing and retrieving messages.
*
* @author Mark Fisher
* @author Iwein Fuld
* @author Dave Syer
* @author Artem Bilan
*
* @since 2.0
*/
public interface MessageStore {
/**
* @param id The message identifier.
* @return The Message with the given id, or <i>null</i> if no Message with that id exists in the MessageStore.
*/
Message<?> getMessage(UUID id);
/**
* Return a {@link MessageMetadata} for the {@link Message} by provided {@code id}.
* @param id The message identifier.
* @return The MessageMetadata with the given id, or <i>null</i>
* if no Message with that id exists in the MessageStore
* or the message has no metadata (legacy message from an earlier version).
* @since 5.0
*/
MessageMetadata getMessageMetadata(UUID id);
/**
* Put the provided Message into the MessageStore. The store may need to mutate the message internally, and if it
* does then the return value can be different than the input. The id of the return value will be used as an index
* so that the {@link #getMessage(UUID)} and {@link #removeMessage(UUID)} behave properly. Since messages are
* immutable, putting the same message more than once is a no-op.
*
* @param message The message.
* @param <T> The payload type.
* @return The message that was stored.
*/
<T> Message<T> addMessage(Message<T> message);
/**
* Remove the Message with the given id from the MessageStore, if present, and return it. If no Message with that id
* is present in the store, this will return <i>null</i>.
*
* @param id THe message identifier.
* @return The message.
*/
Message<?> removeMessage(UUID id);
/**
* Optional attribute giving the number of messages in the store. Implementations may decline to respond by throwing
* an exception.
*
* @return The number of messages.
* @throws UnsupportedOperationException if not implemented
*/
@ManagedAttribute
long getMessageCount();
}