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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/**
* Files replication framework
*
* The
* Replicator allows replicating files between a server and client(s). Producers publish
* revisions and consumers update to the latest revision available.
* ReplicationClient is a helper utility for performing the update operation. It can
* be invoked either
* manually or periodically by
* starting an update thread.
* HttpReplicator can be used to replicate revisions by consumers that reside on
* a different node than the producer.
*
*
* The replication framework supports replicating any type of files, with built-in support for a single search index as
* well as an index and taxonomy pair. For a single index, the application should publish an
* IndexRevision and set
* IndexReplicationHandler on the client. For an index and taxonomy pair, the
* application should publish an IndexAndTaxonomyRevision and set
* IndexAndTaxonomyReplicationHandler on the client.
*
*
* When the replication client detects that there is a newer revision available, it copies the files of the revision and
* then invokes the handler to complete the operation (e.g. copy the files to the index directory, fsync them, reopen an
* index reader etc.). By default, only files that do not exist in the handler's
* current revision files are copied,
* however this can be overridden by extending the client.
*
*
* An example usage of the Replicator:
*
*
* // ++++++++++++++ SERVER SIDE ++++++++++++++ //
* IndexWriter publishWriter; // the writer used for indexing
* Replicator replicator = new LocalReplicator();
* replicator.publish(new IndexRevision(publishWriter));
*
* // ++++++++++++++ CLIENT SIDE ++++++++++++++ //
* // either LocalReplictor, or HttpReplicator if client and server are on different nodes
* Replicator replicator;
*
* // callback invoked after handler finished handling the revision and e.g. can reopen the reader.
* Callable<Boolean> callback = null; // can also be null if no callback is needed
* ReplicationHandler handler = new IndexReplicationHandler(indexDir, callback);
* SourceDirectoryFactory factory = new PerSessionDirectoryFactory(workDir);
* ReplicationClient client = new ReplicationClient(replicator, handler, factory);
*
* // invoke client manually
* client.updateNow();
*
* // or, periodically
* client.startUpdateThread(100); // check for update every 100 milliseconds
*
*/
package org.apache.lucene.replicator;