====
    This work was created by participants in the DataONE project, and is
    jointly copyrighted by participating institutions in DataONE. For
    more information on DataONE, see our web site at http://dataone.org.

      Copyright ${year}

    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

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    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
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    $Id$
====

DataONE Replication Component
-----------------------------

d1_replication is a small set of java classes that manage Member Node to 
Member Node replication of data and metadata objects by monitoring changes
in the DataONE system. This is a component of the Coordinating Node software stack,
and is instantiated by the d1_process_daemon web application.  When additions
or changes to objects are registered on the Coordinating Nodes, the 
ReplicationManager class evaluates the ReplicationPolicy section of the 
SystemMetadata for the given object, along with the Node capabilities for
potential replica Member Nodes, and builds replication tasks that are executed
on a Coordinating Node.  These replication tasks initiate replication by
calling MNReplication.replicate() on the target Member Node.

Object Responsibilities
~~~~~~~~~~~~~~~~~~~~~~~
ReplicationEventListener
 - listens on the systemMetadataMap for changes to SystemMetadata.
 - creates ReplicationTasks in the ReplicationTaskRepository.
 - it's instantiation also triggers the ReplicationManager's instantiation. 

ReplicationManager 
 - upon instantiation initializes scheduled task execution of:
   - QueuedReplicationAuditor
   - StaleReplicationRequestAuditor
   - ReplicationTaskProcessor
 - it contains the logic for evaluating a pid and determining which replicate requests to issue.
   
ReplicationTaskProcessor
 - grabs a page of replicationTasks from the repo, and calls ReplicationManager.createAndQueueTasks
 
StaleReplicationRequestAuditor
 - grabs a page of replicationTasks older than the cutoff and in REQUESTED state
 - resolves them by checking for presence of the replica on the MN.  either COMPLETE, or FAIL
 
QueuedReplicationAuditor
 - by MemberNode 


Installation
------------
Use 'mvn clean install' to install the jar file locally.  The d1_process_daemon
component depends on d1_replication and includes this jar in its deployed
package.

See LICENSE.txt for the details of distributing this software.