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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. 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.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.context;
import java.util.Map;
import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
import org.onap.policy.apex.model.basicmodel.concepts.AxConcept;
import org.onap.policy.apex.model.contextmodel.concepts.AxContextAlbum;
/**
* The Interface ContextAlbum is implemented by all classes that manage context in Apex. Context
* albums may store context in memory, on disk, in a repository or in a mechanism such as a
* distributed map.
*
* <p>A context album uses plugins to handle its context schemas, its distribution, its locking, and
* its persistence.
*
* <p>The schema that defines the items in a context album is interpreted by a plugin that implements
* the {@link SchemaHelper} interface. The schema helper uses the schema definition to provide new
* instances for a context album. By default, context albums use Java schemas.
*
* <p>Context albums may be shared across an arbitrary number of JVMs using a distribution mechanism.
* Apex context distributed context albums using plugins that implement the {@link Distributor}
* interface. By default, context albums use JVM local distribution, that is context albums are only
* available in a single JVM
*
* <p>Items in a context album may be locked across all distributed instances of an album. Apex locks
* instances on context albums using the distributed locking mechanism in a plugin that implements
* the {@link LockManager} interface. By default, context albums use Java locking local to a single
* JVM on each context album instance.
*
* <p>Context albums may be persisted to disk, database, or any other repository. Apex persists context
* albums using the persistence mechanism in a plugin that implements the {@link Persistor}
* interface. By default, context albums use a dummy persistor plugin that does not persist context
* albums.
*
* @author Liam Fallon (liam.fallon@ericsson.com)
*/
public interface ContextAlbum extends Map<String, Object> {
/**
* Gets the key of the context album instance.
*
* @return the key
*/
AxArtifactKey getKey();
/**
* Gets the name of the context album instance.
*
* @return the name
*/
String getName();
/**
* Get the current context album with values.
*
* @return the current context runtime values
*/
AxContextAlbum getAlbumDefinition();
/**
* Get the schema helper for the technology that is handling the schema for this album.
*
* @return the schema helper
*/
SchemaHelper getSchemaHelper();
/**
* Place a read lock on a key in this album across the entire cluster.
*
* @param key The key to lock
* @throws ContextException on locking errors
*/
void lockForReading(String key) throws ContextException;
/**
* Place a write lock on a key in this album across the entire cluster.
*
* @param key The key to lock
* @throws ContextException on locking errors
*/
void lockForWriting(String key) throws ContextException;
/**
* Release the the read lock on a key in this album across the entire cluster.
*
* @param key The key to unlock
* @throws ContextException on locking errors
*/
void unlockForReading(String key) throws ContextException;
/**
* Release the the write lock on a key in this album across the entire cluster.
*
* @param key The key to unlock
* @throws ContextException on locking errors
*/
void unlockForWriting(String key) throws ContextException;
/**
* Get the stack of artifact keys currently using this context item.
*
* @return the keys of the artifacts using the context album at the moment
*/
AxConcept[] getUserArtifactStack();
/**
* Set the stack of artifact keys currently using this context item.
*
* @param userArtifactStack the keys of the artifacts using the context album at the moment
*/
void setUserArtifactStack(AxConcept[] userArtifactStack);
/**
* Flush the context album to the distribution and persistence mechanism.
*
* @throws ContextException On context flush errors
*/
void flush() throws ContextException;
}
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