source: trunk/java-client/org/nzdl/gsdl/service/NzdlMultiWayWrapper.java@ 2316

/*
 *    NzdlMultiWayWrapper.java
 *    Copyright (C) 2001 New Zealand Digital Library Project
 *
 *    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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

//the package we're in
package org.nzdl.gsdl.service;

import java.util.Map;
import java.util.Set;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.List;
import java.util.Date;
import java.util.Hashtable;
import java.util.Properties;
import java.util.Enumeration;
import java.util.Iterator;
import java.io.Writer;
import java.io.FileWriter;
import org.nzdl.gsdl.util.NzdlServiceFactory;
import org.nzdl.gsdl.util.NzdlPreferences;


/**
 * A NzdlMultiWayWrapper is a wrapper around multiple NzdlServices. 
 * It attempts to connect to as many servers as possible and present 
 * them to the user a single collection.
 *
 * When two collections are found to be the same, then only the 
 * collection with the fastest response time for a getCollectionInfo()
 * call is added.
 *
 * @author Brett Sheeran ([email protected]) (comments)
 * @author Stuart Yeates  ([email protected])
 * @see org.nzdl.gsdl.service.NzdlCollectionInfo
 * @version $Revision: 2284 $
 */
public class NzdlMultiWayWrapper
  extends NzdlWrapper {

  Hashtable services;
   
  /** 
   * The bean constructor ...
   */
  public NzdlMultiWayWrapper() {
    super(null);
    services = new Hashtable();
  }
  /** 
   * The normal constructor
   */
  public NzdlMultiWayWrapper(String [] _args,
                 Properties _props,
                 String _URL,
                 String _filename,
                 String _IOR) {
    super(null);
    services = new Hashtable();

    NzdlPreferences.saving = false;

    Hashtable servers = NzdlServiceFactory.findIORs(_args,_props,_URL,_filename,_IOR);
    
    Enumeration e = servers.keys() ;
    for (int i = 0; e.hasMoreElements(); i++) {
      String key = (String)  e.nextElement();
      NzdlService server = (NzdlService) servers.get(key);
      
      if (NzdlPreferences.getBoolean("Log at the NzdlService level"))
    server = new NzdlLogWrapper(server, 
                    "log.file.after.split." + i + ".cache", 
                    "AFTER:" + key + ": ");
      services.put("" +i, server);
    }
  }

  static String findServer(String _name) {
    int separator = _name.indexOf(':');   
    String result = _name.substring(0,separator);
    return result;
  }

  static String findCollection(String _name) {
    String result = "";
    try {
      int separator = _name.indexOf(':');   
      result = _name.substring(separator+1,_name.length());
    } catch (Throwable t) {
      System.err.println("Throwable: "+ t);
    }
    return result;
  }

  /**
   * Allow the client to configure a CORBA server.
   * @param key the parameter to be set.
   * @param values what that parameter will be set to.
   */
  public void configure( String _key, Set _values ) {
    Enumeration e = services.keys();
    for (int i = 0; e.hasMoreElements(); i++) {
      NzdlService server = (NzdlService) e.nextElement();
      server.configure(_key,_values);
    }
  }

  /**
   * Obtain the set of collection names for a Greenstone library.
   * @return A set of collection names in string format.
   */
  public Set getCollectionSet( ) {
    Set results = new HashSet();
    Hashtable intermediate = new Hashtable();

    Enumeration e = services.keys();
    for (int i = 0; e.hasMoreElements(); i++) {
      String name = (String) e.nextElement();
      NzdlService server = (NzdlService) services.get(name);
      Set set = server.getCollectionSet();
      Iterator s = set.iterator();
      while (s.hasNext()) {
    String coll = (String) s.next();
    String collname = "" + i + ":" + coll;
    boolean hit = false;
    for (int j = 0; j < i; j++) {
      String oldcollname = "" + j + ":" + coll;
      if (intermediate.get(oldcollname) != null) {
        
        NzdlService oldServer = (NzdlService) services.get( "" + j );
        Date startOld = new Date();
        NzdlCollectionInfo oldColl = oldServer.getCollectionInfo(coll);
        Date endOld = new Date();
        Date startNew = new Date();
        NzdlCollectionInfo newColl = server.getCollectionInfo(coll);
        Date endNew = new Date();
        
        if (oldColl.getBuildDate() == newColl.getBuildDate() &&
        oldColl.getNumOfDocs() == newColl.getNumOfDocs() &&
        oldColl.getNumOfWords() == newColl.getNumOfWords() &&
        oldColl.getNumOfBytes() == newColl.getNumOfBytes() &&
        oldColl.isPublic() == newColl.isPublic() )
          {
        if ((endOld.getTime() - startOld.getTime()) >
            (endNew.getTime() - startNew.getTime()))
          {
            results.remove(oldcollname);
            results.add(collname);
          }
          }
        hit = true;
      }
    }
    if (hit == false) {
      intermediate.put(collname,collname);
      results.add("" + i + ":" + coll); 
    }
      }
    }
    return results;
  }

  /**
   * Check if ORB knows of this collection.
   * @param name the name of a collecion to be searched for.
   * @return boolean <TT>true</TT> if collection is found, else <TT>false</TT>.
   */
  public boolean hasCollection( String _name ) {

    NzdlService server = (NzdlService) services.get( findServer(_name));
    return  server.hasCollection(findCollection(_name));
   }

  /**
   * Check if ORB can communicate with of this collection.
   * @param name the name of a collecion to be pinged.
   * @return boolean <TT>true</TT> if collection returned ping, else
   * <TT>false</TT>.
   */
  public boolean pingCollection( String _name ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    return server.pingCollection(findCollection(_name));
  }

  /**
   * Extract information on this collection into a
   * {@link NzdlCollectionInfo NzdlCollectionInfo} object
   * @param name the collection to be retrieved.
   * @return an instance of
   * {@link NzdlCollectionInfo NzdlCollectionInfo} containing data on a
   * collection
   */
  public NzdlCollectionInfo getCollectionInfo( String _name ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    NzdlCollectionInfo result = server.getCollectionInfo(findCollection(_name));
    return result;
  }

  /**
   * Returns the set of filters for the service object.
   * @param name the collection name
   * @return a set of strings that name the filters, for example
   * BrowseFilter, QueryFilter and NullFilter.
   */
  public Set getFilterSet( String _name ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    Set result = server.getFilterSet(findCollection(_name));
    return result;
  }

  /**
   * @param name the collection name
   * @return the Set of (name, value) value pairs for all metadata 
   * associated with a collection  
   */
  public Set getMetaTagSet( String _name ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    Set result = server.getMetaTagSet(findCollection(_name));
    return result;
  }

  /**
   * Returns the Greenstone Markup Language (GML) text for a particular
   * document from a collection.
   * @param name the name of the collection.
   * @param docID the document identity string
   * @return the GML document in the form of a string.
   */
  public String getDocument( String _name, String _docID ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    String result = server.getDocument(findCollection(_name), _docID);
    return result;
  }

  /**
   * Returns the set of value(s) for a metatag from a particular document.
   * @param name collection name
   * @param docID the document identifier.
   * @param metaTag the metatag name such as: Title, Author, Date and Images.
   * @return The set of value(s) for the requested metatag and document. In
   * cases such as Title, Author, Date there will probably be only one value
   * per document.
   */
  public Set getMetaData( String _name, String _docID, String _metaTag ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    Set result = server.getMetaData( findCollection(_name), _docID, _metaTag );
    return result;
  }

  /**
   * Returns a map of value(s) for a metatag from a list of documents.
   * @param name collection name
   * @param docIDs a list of document identifier strings.
   * @param metaTag the metatag name such as: Title, Author, Date and Images.
   * @return The map of value(s) for the requested metatag and document. In
   * cases such as Title, Author, Date there will probably be only one value
   * per document.
   */
  public Map getMetaData( String _name, List _docIDs, String _metaTag ) {
    NzdlService server = (NzdlService) services.get( findServer(_name));
    Map result = server.getMetaData( findCollection(_name), _docIDs, _metaTag );
    return result;
  }

  /**
   * Services a {@link NzdlRequest NzdlRequest} to a collection and places
   * the results into a {@link NzdlResponse NzdlResponse} object. <br>
   * Pre:   Created instances of NzdlRequest and NzdlResponse. <br>
   * Post: Placed the result data into NzdlResponse object.
   * @param name the collection name.
   * @param request an instance of NzdlRequest with query data to be serviced
   * @param response an instance of NzdlResponse. where the results of
   * sevciving the query will be placed
   */
  public void service( String _name, NzdlRequest _request, 
               NzdlResponse _response ) {    
    NzdlService server = (NzdlService) services.get( findServer(_name));
    server.service(findCollection(_name),_request,_response);
  }
  
}