Metacat

/**

 *  '$RCSfile$'

 *  Copyright: 2000-2011 Regents of the University of California and the

 *              National Center for Ecological Analysis and Synthesis

 *

 *   '$Author:  $'

 *     '$Date:  $'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.dataone;

import java.util.Date;

import java.util.List;

import java.util.Set;

import org.apache.log4j.Logger;

import org.dataone.configuration.Settings;

import org.dataone.service.cn.v1.CNAuthorization;

import org.dataone.service.cn.v1.CNCore;

import org.dataone.service.cn.v1.CNRead;

import org.dataone.service.cn.v1.CNReplication;

import org.dataone.service.exceptions.IdentifierNotUnique;

import org.dataone.service.exceptions.InsufficientResources;

import org.dataone.service.exceptions.InvalidRequest;

import org.dataone.service.exceptions.InvalidSystemMetadata;

import org.dataone.service.exceptions.InvalidToken;

import org.dataone.service.exceptions.NotAuthorized;

import org.dataone.service.exceptions.NotFound;

import org.dataone.service.exceptions.NotImplemented;

import org.dataone.service.exceptions.ServiceFailure;

import org.dataone.service.types.v1.Checksum;

import org.dataone.service.types.v1.Identifier;

import org.dataone.service.types.v1.Node;

import org.dataone.service.types.v1.NodeList;

import org.dataone.service.types.v1.NodeReference;

import org.dataone.service.types.v1.ObjectFormat;

import org.dataone.service.types.v1.ObjectFormatIdentifier;

import org.dataone.service.types.v1.ObjectFormatList;

import org.dataone.service.types.v1.ObjectList;

import org.dataone.service.types.v1.ObjectLocationList;

import org.dataone.service.types.v1.Permission;

import org.dataone.service.types.v1.Replica;

import org.dataone.service.types.v1.ReplicationPolicy;

import org.dataone.service.types.v1.ReplicationStatus;

import org.dataone.service.types.v1.Session;

import org.dataone.service.types.v1.Subject;

import org.dataone.service.types.v1.SystemMetadata;

import com.hazelcast.client.HazelcastClient;

import com.hazelcast.core.EntryEvent;

import com.hazelcast.core.EntryListener;

import com.hazelcast.core.Hazelcast;

import com.hazelcast.core.IMap;

import com.hazelcast.core.IQueue;

import com.hazelcast.query.SqlPredicate;

import edu.ucsb.nceas.metacat.EventLog;

import edu.ucsb.nceas.metacat.IdentifierManager;

import edu.ucsb.nceas.metacat.McdbDocNotFoundException;

import edu.ucsb.nceas.metacat.properties.PropertyService;

import edu.ucsb.nceas.metacat.replication.ForceReplicationSystemMetadataHandler;

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

/**

 * Represents Metacat's implementation of the DataONE Coordinating Node 

 * service API. Methods implement the various CN* interfaces, and methods common

 * to both Member Node and Coordinating Node interfaces are found in the

 * D1NodeService super class.

 *

 */

public class CNodeService extends D1NodeService implements CNAuthorization,

    CNCore, CNRead, CNReplication, EntryListener<Identifier, SystemMetadata> {

  /* the instance of the CNodeService object */

  private static CNodeService instance = null;

  /* The instance of the Hazelcast client */

  private HazelcastClient hzClient;

  /* The name of the DataONE Hazelcast cluster group */

  private String groupName;

  /* The name of the DataONE Hazelcast cluster password */

  private String groupPassword;

  /* The name of the DataONE Hazelcast cluster IP addresses */

  private String addressList;

  /* The name of the node map */

  private String nodeMap;

  /* The name of the system metadata map */

  private String systemMetadataMap;

  /* The Hazelcast distributed task id generator namespace */

  private String taskIds;

  /* The name of the pending replication tasks map */

  private String pendingTasksQueue;

  /* The Hazelcast distributed system metadata map */

  private IMap<NodeReference, Node> nodes;

  /* The Hazelcast distributed system metadata map */

  private IMap<Identifier, SystemMetadata> systemMetadata;

  /* The Hazelcast distributed pending replication tasks map*/

  private IMap<String, CNReplicationTask> pendingReplicationTasks;

  /* the logger instance */

  private Logger logMetacat = null;

  /**

   * singleton accessor

   */

  public static CNodeService getInstance() { 

    if (instance == null) {

      instance = new CNodeService();

    }

    return instance;

  }

  /**

   * Constructor, private for singleton access

   */

  private CNodeService() {

    super();

    logMetacat = Logger.getLogger(CNodeService.class);

    // Get configuration properties on instantiation

    try {

      groupName = 

        PropertyService.getProperty("dataone.hazelcast.processCluster.groupName");

      groupPassword = 

        PropertyService.getProperty("dataone.hazelcast.processCluster.password");

      addressList = 

        PropertyService.getProperty("dataone.hazelcast.processCluster.instances");

      nodeMap = 

        PropertyService.getProperty("dataone.hazelcast.processCluster.nodesMap");

      systemMetadataMap = 

        PropertyService.getProperty("dataone.hazelcast.storageCluster.systemMetadata");

      taskIds = 

        PropertyService.getProperty("dataone.hazelcast.storageCluster.tasksIdGenerator");

      pendingTasksQueue = 

    	PropertyService.getProperty("dataone.hazelcast.replicationPendingTasks");

      // Become a DataONE-process cluster client

      String[] addresses = addressList.split(",");

      hzClient = 

        HazelcastClient.newHazelcastClient(this.groupName, this.groupPassword, addresses);

      nodes = hzClient.getMap(nodeMap);

      pendingReplicationTasks = hzClient.getMap(pendingTasksQueue);

      // Get a reference to the shared system metadata map as a cluster member

      systemMetadata = Hazelcast.getMap(systemMetadataMap);

      // Listen for changes to the system metadata map

      systemMetadata.addEntryListener(this, true);

    } catch (PropertyNotFoundException e) {

      String msg = "Couldn't find Hazelcast properties for the DataONE clusters. " +

        "The error message was: " + e.getMessage();

      logMetacat.error(msg);

    }

  }

  /**

   * Set the replication policy for an object given the object identifier

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - the object identifier for the given object

   * @param policy - the replication policy to be applied

   * 

   * @return true or false

   * 

   * @throws NotImplemented

   * @throws NotAuthorized

   * @throws ServiceFailure

   * @throws InvalidRequest

   * 

   */

  @Override

  public boolean setReplicationPolicy(Session session, Identifier pid,

    ReplicationPolicy policy) 

    throws NotImplemented, NotFound, NotAuthorized, ServiceFailure, InvalidRequest, InvalidToken {

    // get the subject

    Subject subject = session.getSubject();

    // get the system metadata

    String guid = pid.getValue();

    // are we allowed to do this?

    if (!isAuthorized(session, pid, Permission.CHANGE_PERMISSION)) {

      throw new NotAuthorized("4881", Permission.CHANGE_PERMISSION + " not allowed by " + subject.getValue() + " on " + guid);  

    }

    SystemMetadata systemMetadata = null;

    try {

      systemMetadata = IdentifierManager.getInstance().getSystemMetadata(guid);

    } catch (McdbDocNotFoundException e) {

      throw new NotFound("4884", "No record found for: " + guid);

    }

    // set the new policy

    systemMetadata.setReplicationPolicy(policy);

    // update the metadata

    try {

      IdentifierManager.getInstance().updateSystemMetadata(systemMetadata);

    } catch (McdbDocNotFoundException e) {

      throw new ServiceFailure("4882", e.getMessage());

    }

    return true;

  }

  /**

   * Set the replication status for an object given the object identifier

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - the object identifier for the given object

   * @param status - the replication status to be applied

   * 

   * @return true or false

   * 

   * @throws NotImplemented

   * @throws NotAuthorized

   * @throws ServiceFailure

   * @throws InvalidRequest

   * @throws InvalidToken

   * @throws NotFound

   * 

   */

  @Override

  public boolean setReplicationStatus(Session session, Identifier pid,

    NodeReference targetNode, ReplicationStatus status) 

    throws ServiceFailure, NotImplemented, InvalidToken, NotAuthorized, 

    InvalidRequest, NotFound {

    // get the subject

    Subject subject = session.getSubject();

    // get the system metadata

    String guid = pid.getValue();

    // are we allowed to do this?

    if (!isAuthorized(session, pid, Permission.WRITE)) {

      throw new NotAuthorized("4720", Permission.WRITE + " not allowed by " + subject.getValue() + " on " + guid);  

    }

    SystemMetadata systemMetadata = null;

    try {

      systemMetadata = IdentifierManager.getInstance().getSystemMetadata(guid);

    } catch (McdbDocNotFoundException e) {

      throw new NotFound("4740", "No record found for: " + guid);

    }

    // set the status for each replica

    // TODO: should this method select a certain replica?

    List<Replica> replicas = systemMetadata.getReplicaList();

    for (Replica replica: replicas) {

      replica.setReplicationStatus(status);

    }

    // [re]set the list -- redundant?

    systemMetadata.setReplicaList(replicas);

    // update the metadata

    try {

      IdentifierManager.getInstance().updateSystemMetadata(systemMetadata);

    } catch (McdbDocNotFoundException e) {

      throw new ServiceFailure("4700", e.getMessage());

    }

    return true;

  }

  /**

   * Test that the specified relationship between pidOfSubject and pidOfObject exists

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param node - the node information for the given node be modified

   * 

   * @return true if the relationship exists

   * 

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotAuthorized

   * @throws NotFound

   * @throws InvalidRequest

   * @throws NotImplemented

   */

  @Override

  public boolean assertRelation(Session session, Identifier pidOfSubject, 

    String relationship, Identifier pidOfObject) 

    throws InvalidToken, ServiceFailure, NotAuthorized, NotFound, 

    InvalidRequest, NotImplemented {

    // get the system metadata

    String guid1 = pidOfSubject.getValue();

    // are we allowed to do this?

    if (!isAuthorized(session, pidOfSubject, Permission.READ)) {

      throw new NotAuthorized("4881", Permission.READ + " not allowed on " + guid1);  

    }

    SystemMetadata systemMetadata = null;

    try {

      systemMetadata = IdentifierManager.getInstance().getSystemMetadata(guid1);

    } catch (McdbDocNotFoundException e) {

      throw new NotFound("4884", "No record found for: " + guid1);

    }

    // check relationships

    // TODO: use ORE map

    if (relationship.equalsIgnoreCase("describes")) {

    }

    if (relationship.equalsIgnoreCase("describedBy")) {

    }

    if (relationship.equalsIgnoreCase("derivedFrom")) {

    }

    if (relationship.equalsIgnoreCase("obsoletes")) {

      Identifier pid = systemMetadata.getObsoletes();

      if (pid.getValue().equals(pidOfObject.getValue())) {

        return true;

      }

      //return systemMetadata.getObsoleteList().contains(pidOfObject);

    }

    if (relationship.equalsIgnoreCase("obsoletedBy")) {

      Identifier pid = systemMetadata.getObsoletedBy();

      if (pid.getValue().equals(pidOfObject.getValue())) {

        return true;

      }

      //return systemMetadata.getObsoletedByList().contains(pidOfObject);

    }

    return false;

  }

  /**

   * Return the checksum of the object given the identifier 

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - the object identifier for the given object

   * 

   * @return checksum - the checksum of the object

   * 

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotAuthorized

   * @throws NotFound

   * @throws InvalidRequest

   * @throws NotImplemented

   */

  @Override

  public Checksum getChecksum(Session session, Identifier pid)

    throws InvalidToken, ServiceFailure, NotAuthorized, NotFound, 

    InvalidRequest, NotImplemented {

    if (!isAuthorized(session, pid, Permission.READ)) {

      throw new NotAuthorized("1400", Permission.READ + " not allowed on " + pid.getValue());  

    }

    SystemMetadata systemMetadata = null;

    try {

      systemMetadata = IdentifierManager.getInstance().getSystemMetadata(pid.getValue());

    } catch (McdbDocNotFoundException e) {

      throw new NotFound("1420", "No record found for: " + pid.getValue());

    }

    Checksum checksum = systemMetadata.getChecksum();

    return checksum;

  }

  /**

   * Resolve the location of a given object

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - the object identifier for the given object

   * 

   * @return objectLocationList - the list of nodes known to contain the object

   * 

   * @throws InvalidRequest

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotAuthorized

   * @throws NotFound

   * @throws NotImplemented

   */

  @Override

  public ObjectLocationList resolve(Session session, Identifier pid)

    throws InvalidRequest, InvalidToken, ServiceFailure, NotAuthorized,

    NotFound, NotImplemented {

    throw new NotImplemented("4131", "resolve not implemented");

  }

  /**

   * Search the metadata catalog for identifiers that match the criteria

   * 

   * @param session - the Session object containing the credentials for the Subject

   * @param queryType - An identifier for the type of query expression 

   *                    provided in the query

   * @param query -  The criteria for matching the characteristics of the 

   *                 metadata objects of interest

   * 

   * @return objectList - the list of objects matching the criteria

   * 

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotAuthorized

   * @throws InvalidRequest

   * @throws NotImplemented

   */

  @Override

  public ObjectList search(Session session, String queryType, String query)

    throws InvalidToken, ServiceFailure, NotAuthorized, InvalidRequest,

    NotImplemented {

    ObjectList objectList = null;

    try {

        objectList = 

          IdentifierManager.getInstance().querySystemMetadata(

              null, //startTime, 

              null, //endTime,

              null, //objectFormat, 

              false, //replicaStatus, 

              0, //start, 

              -1 //count

              );

    } catch (Exception e) {

      throw new ServiceFailure("4310", "Error querying system metadata: " + e.getMessage());

    }

      return objectList;

    //throw new NotImplemented("4281", "search not implemented");

    // the code block below is from an older implementation

    /*  This block commented out because of the EcoGrid circular dependency.

         *  For now, query will not be supported until the circularity can be

         *  resolved, probably by moving the ecogrid query syntax transformers

         *  directly into the Metacat codebase.  MBJ 2010-02-03

        try {

            EcogridQueryParser parser = new EcogridQueryParser(request

                    .getReader());

            parser.parseXML();

            QueryType queryType = parser.getEcogridQuery();

            EcogridJavaToMetacatJavaQueryTransformer queryTransformer = 

                new EcogridJavaToMetacatJavaQueryTransformer();

            QuerySpecification metacatQuery = queryTransformer

                    .transform(queryType);

            DBQuery metacat = new DBQuery();

            boolean useXMLIndex = (new Boolean(PropertyService

                    .getProperty("database.usexmlindex"))).booleanValue();

            String xmlquery = "query"; // we don't care the query in resultset,

            // the query can be anything

            PrintWriter out = null; // we don't want metacat result, so set out null

            // parameter: queryspecification, user, group, usingIndexOrNot

            StringBuffer result = metacat.createResultDocument(xmlquery,

                    metacatQuery, out, username, groupNames, useXMLIndex);

            // create result set transfer       

            String saxparser = PropertyService.getProperty("xml.saxparser");

            MetacatResultsetParser metacatResultsetParser = new MetacatResultsetParser(

                    new StringReader(result.toString()), saxparser, queryType

                            .getNamespace().get_value());

            ResultsetType records = metacatResultsetParser.getEcogridResult();

            System.out

                    .println(EcogridResultsetTransformer.toXMLString(records));

            response.setContentType("text/xml");

            out = response.getWriter();

            out.print(EcogridResultsetTransformer.toXMLString(records));

        } catch (Exception e) {

            e.printStackTrace();

        }*/

  }

  /**

   * Returns the object format registered in the DataONE Object Format 

   * Vocabulary for the given format identifier

   * 

   * @param fmtid - the identifier of the format requested

   * 

   * @return objectFormat - the object format requested

   * 

   * @throws InvalidRequest

   * @throws ServiceFailure

   * @throws NotFound

   * @throws InsufficientResources

   * @throws NotImplemented

   */

  @Override

  public ObjectFormat getFormat(ObjectFormatIdentifier fmtid)

    throws InvalidRequest, ServiceFailure, NotFound, InsufficientResources,

    NotImplemented {

      return ObjectFormatService.getInstance().getFormat(fmtid);

  }

  /**

   * Returns a list of all object formats registered in the DataONE Object 

   * Format Vocabulary

    * 

   * @return objectFormatList - The list of object formats registered in 

   *                            the DataONE Object Format Vocabulary

   * 

   * @throws InvalidRequest

   * @throws ServiceFailure

   * @throws NotImplemented

   * @throws NotFound

   * @throws InsufficientResources

   */

  @Override

  public ObjectFormatList listFormats() 

    throws InvalidRequest, ServiceFailure, NotFound, InsufficientResources, 

    NotImplemented {

    return ObjectFormatService.getInstance().listFormats();

  }

  /**

   * Returns a list of nodes that have been registered with the DataONE infrastructure

    * 

   * @return nodeList - List of nodes from the registry

   * 

   * @throws ServiceFailure

   * @throws NotImplemented

   */

  @Override

  public NodeList listNodes() 

    throws NotImplemented, ServiceFailure {

    throw new NotImplemented("4800", "listNodes not implemented");

  }

  /**

   * Provides a mechanism for adding system metadata independently of its 

   * associated object, such as when adding system metadata for data objects.

    * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - The identifier of the object to register the system metadata against

   * @param sysmeta - The system metadata to be registered

   * 

   * @return true if the registration succeeds

   * 

   * @throws NotImplemented

   * @throws NotAuthorized

   * @throws ServiceFailure

   * @throws InvalidRequest

   * @throws InvalidSystemMetadata

   */

  @Override

  public Identifier registerSystemMetadata(Session session, Identifier guid,

    SystemMetadata sysmeta) 

    throws NotImplemented, NotAuthorized, ServiceFailure, InvalidRequest, 

    InvalidSystemMetadata {

    // TODO: control who can call this?

        if (session == null) {

            //TODO: many of the thrown exceptions do not use the correct error codes

            //check these against the docs and correct them

            throw new NotAuthorized("4861", "No Session - could not authorize for registration." +

                    "  If you are not logged in, please do so and retry the request.");

        }

        // verify that guid == SystemMetadata.getIdentifier()

        logMetacat.debug("Comparing guid|sysmeta_guid: " + guid.getValue() + "|" + sysmeta.getIdentifier().getValue());

        if (!guid.getValue().equals(sysmeta.getIdentifier().getValue())) {

            throw new InvalidRequest("4863", 

                "GUID in method call (" + guid.getValue() + ") does not match GUID in system metadata (" +

                sysmeta.getIdentifier().getValue() + ").");

        }

        logMetacat.debug("Checking if identifier exists...");

        // Check that the identifier does not already exist

        if (IdentifierManager.getInstance().identifierExists(guid.getValue())) {

            throw new InvalidRequest("4863", 

                "GUID is already in use by an existing object.");

        }

        // insert the system metadata into the object store

        logMetacat.debug("Starting to insert SystemMetadata...");

        sysmeta.setDateSysMetadataModified(new Date());

        try {

          IdentifierManager.getInstance().createSystemMetadata(sysmeta);

          // force replication of this record

          ForceReplicationSystemMetadataHandler forceReplication = 

            new ForceReplicationSystemMetadataHandler(guid.getValue(), null);

        } catch (Exception e) {

            throw new ServiceFailure("4862", "Error inserting system metadata: " + e.getClass() + ": " + e.getMessage());

        }

        logMetacat.debug("Returning from registerSystemMetadata");

        EventLog.getInstance().log(null, session.getSubject().getValue(), guid.getValue(), "registerSystemMetadata");

        return guid;

  }

  /**

   * Provides a mechanism for updating system metadata independently of its 

   * associated object

    * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - The identifier of the system metadata

   * @param sysmeta - The system metadata to be registered

   * 

   * @return true if the update succeeds

   * 

   * @throws NotImplemented

   * @throws NotAuthorized

   * @throws ServiceFailure

   * @throws InvalidRequest

   * @throws InvalidSystemMetadata

   * @throws NotFound

   */

  @Override

  public boolean updateSystemMetadata(Session session, Identifier guid,

    SystemMetadata sysmeta) 

    throws NotImplemented, NotAuthorized, ServiceFailure, InvalidRequest, 

    InvalidSystemMetadata, NotFound {

    // TODO: control who can call this?

        if (session == null) {

            //TODO: many of the thrown exceptions do not use the correct error codes

            //check these against the docs and correct them

            throw new NotAuthorized("4861", "No Session - could not authorize for update." +

                    "  If you are not logged in, please do so and retry the request.");

        }

        // verify that guid == SystemMetadata.getIdentifier()

        logMetacat.debug("Comparing guid|sysmeta_guid: " + guid.getValue() + "|" + sysmeta.getIdentifier().getValue());

        if (!guid.getValue().equals(sysmeta.getIdentifier().getValue())) {

            throw new InvalidRequest("4863", 

                "GUID in method call (" + guid.getValue() + ") does not match GUID in system metadata (" +

                sysmeta.getIdentifier().getValue() + ").");

        }

        logMetacat.debug("Checking if identifier exists...");

        // Check that the identifier exists

        if (!IdentifierManager.getInstance().identifierExists(guid.getValue())) {

            throw new NotFound("000", 

                "GUID does not exist");

        }

        // update the system metadata into the object store

        logMetacat.debug("Starting to update SystemMetadata...");

        sysmeta.setDateSysMetadataModified(new Date());

        try {

          IdentifierManager.getInstance().updateSystemMetadata(sysmeta);

          // force replication of this record

          ForceReplicationSystemMetadataHandler forceReplication = 

            new ForceReplicationSystemMetadataHandler(guid.getValue(), null);

        } catch (Exception e) {

            throw new ServiceFailure("4862", "Error updating system metadata: " + e.getClass() + ": " + e.getMessage());

        }

        logMetacat.debug("Returning from updateSystemMetadata");

        EventLog.getInstance().log(null, session.getSubject().getValue(), guid.getValue(), "updateSystemMetadata");

        return true;

  }

  /**

   * Given an optional scope and format, reserves and returns an identifier 

   * within that scope and format that is unique and will not be 

   * used by any other sessions. 

    * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - The identifier of the object to register the system metadata against

   * @param scope - An optional string to be used to qualify the scope of 

   *                the identifier namespace, which is applied differently 

   *                depending on the format requested. If scope is not 

   *                supplied, a default scope will be used.

   * @param format - The optional name of the identifier format to be used, 

   *                  drawn from a DataONE-specific vocabulary of identifier 

   *                 format names, including several common syntaxes such 

   *                 as DOI, LSID, UUID, and LSRN, among others. If the 

   *                 format is not supplied by the caller, the CN service 

   *                 will use a default identifier format, which may change 

   *                 over time.

   * 

   * @return true if the registration succeeds

   * 

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotAuthorized

   * @throws IdentifierNotUnique

   * @throws NotImplemented

   */

  @Override

  public boolean reserveIdentifier(Session session, Identifier pid)

  throws InvalidToken, ServiceFailure,

        NotAuthorized, IdentifierNotUnique, NotImplemented, InvalidRequest {

    throw new NotImplemented("4191", "reserveIdentifier not implemented on this node");

  }

  @Override

  public Identifier generateIdentifier(Session session, String scheme, String fragment)

  throws InvalidToken, ServiceFailure,

        NotAuthorized, NotImplemented, InvalidRequest {

    throw new NotImplemented("4191", "generateIdentifier not implemented on this node");

  }

  /**

    * Checks whether the pid is reserved by the subject in the session param

    * If the reservation is held on the pid by the subject, we return true.

    * 

   * @param session - the Session object containing the Subject

   * @param pid - The identifier to check

   * 

   * @return true if the reservation exists for the subject/pid

   * 

   * @throws InvalidToken

   * @throws ServiceFailure

   * @throws NotFound - when the pid is not found (in use or in reservation)

   * @throws NotAuthorized - when the subject does not hold a reservation on the pid

   * @throws IdentifierNotUnique - when the pid is in use

   * @throws NotImplemented

   */

  @Override

  public boolean hasReservation(Session session, Identifier pid) 

      throws InvalidToken, ServiceFailure, NotFound, NotAuthorized, IdentifierNotUnique, 

      NotImplemented, InvalidRequest {

      throw new NotImplemented("4191", "hasReservation not implemented on this node");

  }

  /**

   * Changes ownership (RightsHolder) of the specified object to the 

   * subject specified by userId

    * 

   * @param session - the Session object containing the credentials for the Subject

   * @param pid - Identifier of the object to be modified

   * @param userId - The subject that will be taking ownership of the specified object.

   *

   * @return pid - the identifier of the modified object

   * 

   * @throws ServiceFailure

   * @throws InvalidToken

   * @throws NotFound

   * @throws NotAuthorized

   * @throws NotImplemented

   * @throws InvalidRequest

   */  

  @Override

  public Identifier setOwner(Session session, Identifier pid, Subject userId)

    throws InvalidToken, ServiceFailure, NotFound, NotAuthorized,

    NotImplemented, InvalidRequest {

    // get the subject

    Subject subject = session.getSubject();

    // get the system metadata

    String guid = pid.getValue();

    // are we allowed to do this?

    if (!isAuthorized(session, pid, Permission.CHANGE_PERMISSION)) {

      throw new NotAuthorized("4440", "not allowed by " + subject.getValue() + " on " + guid);  

    }

    SystemMetadata systemMetadata = null;

    try {

      systemMetadata = IdentifierManager.getInstance().getSystemMetadata(guid);

    } catch (McdbDocNotFoundException e) {

      throw new NotFound("4460", "No record found for: " + guid);

    }

    // set the new rights holder

    systemMetadata.setRightsHolder(userId);

    // update the metadata

    try {

      IdentifierManager.getInstance().updateSystemMetadata(systemMetadata);

    } catch (McdbDocNotFoundException e) {

      throw new ServiceFailure("4490", e.getMessage());

    }

    return pid;

  }

  /**

   * Verify that a replication task is authorized by comparing the target node's

   * Subject (from the X.509 certificate-derived Session) with the list of 

   * subjects in the known, pending replication tasks map.

   * 

   * @param originatingNodeSession - Session information that contains the 

   *                                 identity of the calling user

   * @param targetNodeSubject - Subject identifying the target node

   * @param pid - the identifier of the object to be replicated

   * @param replicatePermission - the execute permission to be granted

   * 

   * @throws ServiceFailure

   * @throws NotImplemented

   * @throws InvalidToken

   * @throws NotAuthorized

   * @throws InvalidRequest

   * @throws NotFound

   */

  @Override

  public boolean isNodeAuthorized(Session originatingNodeSession, 

    Subject targetNodeSubject, Identifier pid, Permission replicatePermission) 

    throws NotImplemented, NotAuthorized, InvalidToken, ServiceFailure, 

    NotFound, InvalidRequest {

	// build a predicate like: 

	    // "pid                    = '{pid}                   ' AND 

	    //  pemission              = '{permission}            ' AND

	    //  originatingNodeSubject = '{originatingNodeSubject}' AND

	    //  targetNodeSubject      = '{targetNodeSubject}     '"

	    boolean isAllowed = false;

	    String query = "";

	    query += "pid = '";

	    query += pid;

	    query += "' AND permission = '";

	    query += replicatePermission.name();

	    query += "' AND originatingNodeSubject = '";

	    query += originatingNodeSession.getSubject().getValue();

	    query += "' AND targetNodeSubject = '";

	    query += targetNodeSubject.getValue();

	    query += "'";

	    logMetacat.debug("Pending replication task query is: " + query);

	    // search the hzPendingReplicationTasks map for the  originating node subject, 

	    // target node subject, pid, and replicate permission

	    Set<CNReplicationTask> tasks = 

	      (Set<CNReplicationTask>) this.pendingReplicationTasks.values(new SqlPredicate(query));

	    // do we have a matching task?

	    if ( tasks.size() >= 1 ) {

	      isAllowed = true;

	    }

	    return isAllowed;

  }

  /**

   * Implement the EntryListener interface for Hazelcast, reponding to entry

   * added events in the hzSystemMetadata map.  Evaluate the entry and create

   * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

   * 

   * @param event - The EntryEvent that occurred

   */

  @Override

  public void entryAdded(EntryEvent<Identifier, SystemMetadata> event) {

    // TODO evaluate the type of system metadata change, decide if it warrants

    // a replication event, what type (DATA, METADATA, RESOURCE), 

    // iteratively lock the PID, create and submit the tasks, and expect a result back. 

    // Deal with exceptions.

  }

  /**

   * Implement the EntryListener interface for Hazelcast, reponding to entry

   * evicted events in the hzSystemMetadata map.  Evaluate the entry and create

   * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

   * 

   * @param event - The EntryEvent that occurred

   */

  @Override

  public void entryEvicted(EntryEvent<Identifier, SystemMetadata> event) {

    // nothing to do, entries are still in the backing store

  }

  /**

   * Implement the EntryListener interface for Hazelcast, reponding to entry

   * removed events in the hzSystemMetadata map.  Evaluate the entry and create

   * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

   * 

   * @param event - The EntryEvent that occurred

   */

  @Override

  public void entryRemoved(EntryEvent<Identifier, SystemMetadata> event) {

    // we don't remove objects

  }

  /**

   * Implement the EntryListener interface for Hazelcast, reponding to entry

   * updated events in the hzSystemMetadata map.  Evaluate the entry and create

   * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

   * 

   * @param event - The EntryEvent that occurred

   */

  @Override

  public void entryUpdated(EntryEvent<Identifier, SystemMetadata> event) {

    // TODO evaluate the type of system metadata change, decide if it warrants

    // a replication event, what type (DATA, METADATA, RESOURCE), 

    // iteratively lock the PID, create and submit the tasks, and expect a result back. 

    // Deal with exceptions.

  }

}