source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/service/FedoraServiceProxy.java@ 26170

/*
 *    ServiceRack.java
 *    Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
 *
 *    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.
 */
package org.greenstone.gsdl3.service;

// greenstone classes
import java.io.StringReader;
import java.util.HashMap;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.log4j.Logger;
import org.greenstone.gs3client.dlservices.DigitalLibraryServicesAPIA;
import org.greenstone.gs3client.dlservices.FedoraServicesAPIA;
import org.greenstone.gsdl3.core.MessageRouter;
import org.greenstone.gsdl3.util.Dictionary;
import org.greenstone.gsdl3.util.GSPath;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.MacroResolver;
import org.greenstone.gsdl3.util.OID;
import org.greenstone.gsdl3.util.XMLConverter;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;


/*
// greenstone classes
import org.greenstone.gsdl3.util.*;
import org.greenstone.gsdl3.core.*;

// for fedora
import org.greenstone.gs3client.dlservices.*;
import org.greenstone.fedora.services.FedoraGS3Exception.CancelledException;

// xml classes
import org.w3c.dom.Node; 
import org.w3c.dom.NodeList; 
import org.w3c.dom.Element; 
import org.w3c.dom.Document; 
import org.xml.sax.InputSource;
import javax.xml.parsers.*;
import org.apache.xpath.XPathAPI;

// general java classes
import java.io.Reader;
import java.io.StringReader;
import java.io.File;
import java.util.HashMap;
import java.util.Locale;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.regex.*;
import java.lang.reflect.Method;
*/

import org.apache.log4j.*;

/**
 * FedoraServiceProxy - communicates with the FedoraGS3 interface.
 *
 * @author Anupama Krishnan
 */
public class FedoraServiceProxy
    extends ServiceRack implements OID.OIDTranslatable
{
    public static class BasicTextMacroResolver extends MacroResolver {  
    public String resolve(String text, String lang, String scope, String doc_oid) 
    {

        if (text == null || text.equals("")) {
        return text;
        }       
        if (!scope.equals(SCOPE_TEXT) || text_macros.size()==0) {
        return text;
        }

        java.util.ArrayList macros = text_macros;
        for (int i=0; i<macros.size(); i++) {
        String new_text = null;
        Macro m = (Macro)macros.get(i);
        if(m.type == TYPE_TEXT) {
            // make sure we resolve any macros in the text
            // the (?s) treats the string as a single line, cos . 
            // doesn't necessarily match line breaks
            //if (text.matches("(?s).*"+m.macro+".*")) {
            Pattern p_text = Pattern.compile(".*" + m.macro + ".*",Pattern.DOTALL);
            Matcher match_text = p_text.matcher(text);
            if (match_text.matches()) {
            if (m.resolve) {
                new_text = this.resolve(m.text, lang, scope, doc_oid);
            } else {
                new_text = m.text;
            }
            text = text.replaceAll(m.macro, new_text);
            if (m.macro.endsWith("\\\\")){ // to get rid of "\" from the string likes: "src="http://www.greenstone.org:80/.../mw.gif\">"
                Pattern p_back_slash = Pattern.compile("\\\"");// create a pattern "\\\"", but it matches both " and \"
                Matcher m_slash = p_back_slash.matcher(text);
                String clean_str = "";
                int s=0;
                while (m_slash.find()){
                if (!text.substring(m_slash.end()-2,m_slash.end()-1).equals("\\")){
                    clean_str = clean_str + text.substring(s,m_slash.end()-1); // it matches ", so get a substring before "
                }else{
                    clean_str = clean_str + text.substring(s,m_slash.end()-2);// it matches \", so get a substring before \
                    }
                s = m_slash.end();// get the index of the last match
                clean_str = clean_str + "\"";
                }
                text = clean_str + text.substring(s,text.length());
            }
            }
        }       
        }
        return text;
    }
    }

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.service.FedoraServiceProxy.class.getName());
    protected MacroResolver macro_resolver = null;


    /** The handle to the fedora connection */
    private DigitalLibraryServicesAPIA fedoraServicesAPIA;

    private String prevLanguage = "";

    public void cleanUp() { 
    super.cleanUp();
    }
    
    /** sets the message router */
    public void setMessageRouter(MessageRouter m) {
       this.router = m;
       setLibraryName(m.getLibraryName());
    }

    /** the no-args constructor */
    public FedoraServiceProxy() {
    super();

    this.converter = new XMLConverter();
    this.doc = this.converter.newDOM();
    this.short_service_info = this.doc.createElement(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER);
    this.macro_resolver = new BasicTextMacroResolver();
    }
    

    /* configure the service module
     *
     * @param info the XML node <serviceRack name="XXX"/> with name equal
     * to the class name (of the subclass)
     *
     * must configure short_service_info_ and service_info_map_
     * @return true if configured ok
     * must be implemented in subclasses
     */
    /*public boolean configure(Element info) {
    return configure(info, null);
    }*/
    
    public boolean configure(Element info, Element extra_info) {
    // set up the class loader
        
    if (!super.configure(info, extra_info)){
        return false;
    }

    // Try to instantiate a Fedora dl handle
    try {
        // Fedora connection settings defaults. 
        // Read host and port from global.properties, since by default, we expect the Greenstone server to be used
        Properties globalProperties = new Properties();
        globalProperties.load(Class.forName("org.greenstone.util.GlobalProperties").getClassLoader().getResourceAsStream("global.properties"));
        String host = globalProperties.getProperty("tomcat.server", "localhost");
        String port = globalProperties.getProperty("tomcat.port", "8383");
        String protocol = "http";
        String username = "fedoraIntCallUser"; //"fedoraAdmin"
        String password = "changeme"; //"<user password>"

        // See if buildConfig.xml overrides any of the defaults
        // info is the <serviceRack> Element from buildConfig.xml (extra_info are the Elements of collectionConfig.xml)

        NodeList nodes = info.getElementsByTagName("fedoraConnection");
        if(nodes != null && nodes.getLength() > 0) {

        Element fedoraElement = (Element)nodes.item(0);
        if(fedoraElement.hasAttribute("protocol")) {
            protocol = fedoraElement.getAttribute("protocol");
        }       
        if(fedoraElement.hasAttribute("host")) {
            host = fedoraElement.getAttribute("host");
        }
        if(fedoraElement.hasAttribute("port")) {
            port = fedoraElement.getAttribute("port");
        }
        if(fedoraElement.hasAttribute("username")) {
            username = fedoraElement.getAttribute("username");
        }
        if(fedoraElement.hasAttribute("password")) {
            password = fedoraElement.getAttribute("password");
        }       
        }   

        fedoraServicesAPIA = new FedoraServicesAPIA(protocol, host, Integer.parseInt(port), username, password);

    } catch(org.greenstone.fedora.services.FedoraGS3Exception.CancelledException e) {
        // The user pressed cancel in the fedora services instantiation dialog
        return false;
    } catch(Exception e) {
        logger.error("Error instantiating the interface to the Fedora Repository:\n", e); // second parameter prints e's stacktrace
        return false;
    } 

    
    // Need to put the available services into short_service_info
    // This is used by DefaultReceptionist.process() has an exception. But DefaultReceptionist.addExtraInfo() 
    // isn't helpful, and the problem actually already occurs in 
    // Receptionist.process() -> PageAction.process() -> MessageRouter.process() 
    // -> Collection/ServiceCluster.process() -> ServiceCluster.configureServiceRackList() 
    // -> ServiceRack.process() -> ServiceRack.processDescribe() -> ServiceRack.getServiceList().
    // ServiceRack.getServiceList() requires this ServiceRack's services to be filled into the 
    // short_service_info Element which needs to be done in this FedoraServiceProxy.configure().
    
    // get the display and format elements from the coll config file for
    // the classifiers
    AbstractBrowse.extractExtraClassifierInfo(info, extra_info);

    // Copied from IViaProxy.java:
    String collection = fedoraServicesAPIA.describeCollection(this.cluster_name);

    Element collNode = getResponseAsDOM(collection);
    Element serviceList = (Element)collNode.getElementsByTagName(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER).item(0);

//this.short_service_info.appendChild(short_service_info.getOwnerDocument().importNode(serviceList, true));
    // we want the individual service Elements, not the serviceList Element which will wrap it later
    NodeList services = collNode.getElementsByTagName(GSXML.SERVICE_ELEM);
    for(int i = 0; i < services.getLength(); i++) {
        Node service = services.item(i);
        this.short_service_info.appendChild(short_service_info.getOwnerDocument().importNode(service, true));
    }

    // add some format info to service map if there is any
    String path = GSPath.appendLink(GSXML.SEARCH_ELEM, GSXML.FORMAT_ELEM);
    Element search_format = (Element) GSXML.getNodeByPath(extra_info, path);
    if (search_format != null) {
        this.format_info_map.put("TextQuery", this.doc.importNode(search_format, true));
    }
    
    // look for document display format
    path = GSPath.appendLink(GSXML.DISPLAY_ELEM, GSXML.FORMAT_ELEM);
    Element display_format = (Element)GSXML.getNodeByPath(extra_info, path);
    if (display_format != null) {
        this.format_info_map.put("DocumentContentRetrieve", this.doc.importNode(display_format, true));
        // should we make a copy?
    }

    // the format info
    Element cb_format_info = this.doc.createElement(GSXML.FORMAT_ELEM);
    boolean format_found = false;

    // look for classifier <browse><format>
    path = GSPath.appendLink(GSXML.BROWSE_ELEM, GSXML.FORMAT_ELEM);
    Element browse_format = (Element)GSXML.getNodeByPath(extra_info, path);
    if (browse_format != null) {
        cb_format_info.appendChild(GSXML.duplicateWithNewName(this.doc, browse_format, GSXML.DEFAULT_ELEM, true));
        format_found = true;
    } 
    
    // add in to the description a simplified list of classifiers
    Element browse = (Element)GSXML.getChildByTagName(extra_info, "browse"); // the <browse>
    NodeList classifiers = browse.getElementsByTagName(GSXML.CLASSIFIER_ELEM);
    for(int i=0; i<classifiers.getLength(); i++) {
        Element cl = (Element)classifiers.item(i);
        Element new_cl = (Element)this.doc.importNode(cl, false); // just import this node, not the children
        
        // get the format info out, and put inside a classifier element
        Element format_cl = (Element)new_cl.cloneNode(false);
        Element format = (Element)GSXML.getChildByTagName(cl, GSXML.FORMAT_ELEM);
        if (format != null) {
        
        //copy all the children
        NodeList elems = format.getChildNodes();
        for (int j=0; j<elems.getLength();j++) {
            format_cl.appendChild(this.doc.importNode(elems.item(j), true));
        }
        cb_format_info.appendChild(format_cl);
        format_found = true;
        }
                
    }
        
    if (format_found) {
        this.format_info_map.put("ClassifierBrowse", cb_format_info);
    }
    

    // set up the macro resolver
    macro_resolver.setSiteDetails(this.site_http_address, this.cluster_name, this.getLibraryName());
    Element replacement_elem = (Element)GSXML.getChildByTagName(extra_info, "replaceList");
    if (replacement_elem != null) {
        macro_resolver.addMacros(replacement_elem);
    }
    // look for any refs to global replace lists
    NodeList replace_refs_elems = extra_info.getElementsByTagName("replaceListRef");
    for (int i=0; i<replace_refs_elems.getLength(); i++) {
        String id = ((Element)replace_refs_elems.item(i)).getAttribute("id");
        if (!id.equals("")) {
        Element replace_list = GSXML.getNamedElement(this.router.config_info, "replaceList", "id", id);
        if (replace_list != null) {
            macro_resolver.addMacros(replace_list);
        }
        }
    }

    // configured ok
    return true;
    }

  
    /* "DocumentContentRetrieve", "DocumentMetadataRetrieve", "DocumentStructureRetrieve", 
      "TextQuery", "FieldQuery", "ClassifierBrowse", "ClassifierBrowseMetadataRetrieve" */

    protected Element processDocumentContentRetrieve(Element request) {
    String[] docIDs = parse(request, GSXML.DOC_NODE_ELEM, GSXML.NODE_ID_ATT); 
    String[] relLinks = parse(request, GSXML.DOC_NODE_ELEM, "externalURL");
    
    //logger.error("### request:"); 
    //logger.error(GSXML.nodeToFormattedString(request));

    if(docIDs == null) {
        logger.error("DocumentContentRetrieve request specified no doc nodes.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    } else {
        for(int i = 0; i < docIDs.length; i++) {
        //logger.error("BEFORE: docIDs[" + i + "]: " + docIDs[i]);
        if(relLinks[i] != null && docIDs[i].startsWith("http://")) { // need to do a look up
            docIDs[i] = translateExternalId(docIDs[i]);
        } else {
            docIDs[i] = translateId(docIDs[i]);         
        }
        //logger.error("AFTER: docIDs[" + i + "]: " + docIDs[i]);
        }
    }
    
    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }
    
    // first param (the collection) is not used by Fedora   
    Element response = getResponseAsDOM(fedoraServicesAPIA.retrieveDocumentContent(this.cluster_name, docIDs));

    
    // resolve any collection specific macros
    NodeList nodeContents = response.getElementsByTagName(GSXML.NODE_CONTENT_ELEM);
    for(int i = 0; i < nodeContents.getLength(); i++) {
        Element nodeContent = (Element)nodeContents.item(i);
        /*if(nodeContent != null) {
        nodeContent = (Element)nodeContent.getFirstChild(); // textNode
        }*/
        //logger.error("GIRAFFE 1. content retrieve response - nodeContent: " + GSXML.nodeToFormattedString(nodeContent));
        String docContent = nodeContent.getFirstChild().getNodeValue(); // getTextNode and get its contents.
        //logger.error("GIRAFFE 2. content retrieve response - docContent: " + docContent);
        
        if(docContent != null) {
        // get document text and resolve and macros. Rel and external links have _httpextlink_ set by HTMLPlugin
        docContent = macro_resolver.resolve(docContent, lang, MacroResolver.SCOPE_TEXT, ""); // doc_id
        nodeContent.getFirstChild().setNodeValue(docContent);
        //logger.error("GIRAFFE 3. content retrieve response. Updated docContent: " + docContent);
        }
    }

    return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0); 
    }

    protected Element processDocumentStructureRetrieve(Element request) {
    String[] docIDs = parse(request, GSXML.DOC_NODE_ELEM, GSXML.NODE_ID_ATT);
    String[] relLinks = parse(request, GSXML.DOC_NODE_ELEM, "externalURL"); 

    if(docIDs == null) {
        logger.error("DocumentStructureRetrieve request specified no doc nodes.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    } else {
        for(int i = 0; i < docIDs.length; i++) {
        //logger.error("BEFORE: docIDs[" + i + "]: " + docIDs[i]);
        if(relLinks[i] != null && docIDs[i].startsWith("http://")) { // need to do a look up
            docIDs[i] = translateExternalId(docIDs[i]);
        } else {
            docIDs[i] = translateId(docIDs[i]);
        }
        }
    }

    NodeList params = request.getElementsByTagName(GSXML.PARAM_ELEM);
    String structure="";
    String info="";
    for(int i = 0; i < params.getLength(); i++) {
        Element param = (Element)params.item(i);
        if(param.getAttribute("name").equals("structure")) {
        structure = structure + param.getAttribute("value") + "|";
        } else if(param.getAttribute("name").equals("info")) {
        info = info + param.getAttribute("value") + "|";
        }
    }   
    
    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }
    Element response = getResponseAsDOM(fedoraServicesAPIA.retrieveDocumentStructure(
        this.cluster_name, docIDs, new String[]{structure}, new String[]{info}));
    return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0); 
    }

    protected Element processDocumentMetadataRetrieve(Element request) {
    String[] docIDs = parse(request, GSXML.DOC_NODE_ELEM, GSXML.NODE_ID_ATT);
    String[] relLinks = parse(request, GSXML.DOC_NODE_ELEM, "externalURL");

    if(docIDs == null) {
        logger.error("DocumentMetadataRetrieve request specified no doc nodes.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    } else {
        for(int i = 0; i < docIDs.length; i++) {
        //logger.error("**** relLinks[i]: " + relLinks[i]);
        //logger.error("**** docIDs[i]: " + docIDs[i]);
        if(relLinks[i] != null && docIDs[i].startsWith("http://")) { // need to do a look up
            docIDs[i] = translateExternalId(docIDs[i]);
        } else {
            docIDs[i] = translateId(docIDs[i]);
        }
        //logger.error("AFTER: docIDs[" + i + "]: " + docIDs[i]);
        }
    }
    
    NodeList params = request.getElementsByTagName(GSXML.PARAM_ELEM);
    String[] metafields = {};
    if(params.getLength() > 0) {
        metafields = new String[params.getLength()];
        for(int i = 0; i < metafields.length; i++) {
        Element param = (Element)params.item(i);
        //if(param.hasAttribute(GSXML.NAME_ATT) && param.getAttribute(GSXML.NAME_ATT).equals("metadata") && param.hasAttribute(GSXML.VALUE_ATT)) {
        if(param.hasAttribute(GSXML.VALUE_ATT)){ 
            metafields[i] = param.getAttribute(GSXML.VALUE_ATT);
        } else {
            metafields[i] = "";
        }
        }
    }

    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }
    Element response = getResponseAsDOM(fedoraServicesAPIA.retrieveDocumentMetadata(
                        this.cluster_name, docIDs, metafields));
    return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0); 
    }

    protected Element processClassifierBrowseMetadataRetrieve(Element request) {    
    String[] classIDs = parse(request, GSXML.CLASS_NODE_ELEM, GSXML.NODE_ID_ATT);
    //String[] relLinks = parse(request, GSXML.CLASS_NODE_ELEM, "externalURL");

    if(classIDs == null) {
        logger.error("ClassifierBrowseMetadataRetrieve request specified no classifier nodes.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    } else {
        for(int i = 0; i < classIDs.length; i++) {
        classIDs[i] = translateId(classIDs[i]);
        }
    }
    
    NodeList params = request.getElementsByTagName(GSXML.PARAM_ELEM);
    String[] metafields = {};
    if(params.getLength() > 0) {
        metafields = new String[params.getLength()];
        for(int i = 0; i < metafields.length; i++) {
        Element param = (Element)params.item(i);
        if(param.hasAttribute(GSXML.VALUE_ATT)){ 
            metafields[i] = param.getAttribute(GSXML.VALUE_ATT);
        } else {
            metafields[i] = "";
        }
        }
    }
    
    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }
    Element response = getResponseAsDOM(fedoraServicesAPIA.retrieveBrowseMetadata(
           this.cluster_name, "ClassifierBrowseMetadataRetrieve", classIDs, metafields));
    return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0);
    }

    protected Element processClassifierBrowse(Element request) {
    String collection = this.cluster_name;
    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }

    NodeList classNodes = request.getElementsByTagName(GSXML.CLASS_NODE_ELEM);
    if(classNodes == null || classNodes.getLength() <= 0) {
        logger.error("ClassifierBrowse request specified no classifier IDs.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    }
    String classifierIDs[] = new String[classNodes.getLength()];
    for(int i = 0; i < classifierIDs.length; i++) {
        Element e = (Element)classNodes.item(i);
        classifierIDs[i] = e.getAttribute(GSXML.NODE_ID_ATT);
        classifierIDs[i] = translateId(classifierIDs[i]);   
    }
    
    NodeList params = request.getElementsByTagName(GSXML.PARAM_ELEM);
    String structure="";
    String info="";
    for(int i = 0; i < params.getLength(); i++) {
        Element param = (Element)params.item(i);
        if(param.getAttribute("name").equals("structure")) {
        structure = structure + param.getAttribute("value") + "|";
        } else if(param.getAttribute("name").equals("info")) {
        info = info + param.getAttribute("value") + "|";
        }
    }
    ///structure = structure + "siblings"; //test for getting with classifier browse structure: siblings
    
    Element response 
        = getResponseAsDOM(fedoraServicesAPIA.retrieveBrowseStructure(collection, "ClassifierBrowse", classifierIDs,
                                      new String[] {structure}, new String[] {info}));
    ///logger.error("**** FedoraServiceProxy - Response from retrieveBrowseStructure: " + GSXML.nodeToFormattedString(response));   
    
    return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0);
    }

    protected Element processTextQuery(Element request) {
    return processQuery(request, "TextQuery");
    }

    protected Element processFieldQuery(Element request) {
    return processQuery(request, "FieldQuery");
    }

    protected Element processQuery(Element request, String querytype) {
    String collection = this.cluster_name;

    String lang = request.getAttribute(GSXML.LANG_ATT);
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }

    NodeList paramNodes = request.getElementsByTagName(GSXML.PARAM_ELEM);
    if(paramNodes.getLength() > 0) {
        HashMap<String, String> params = new HashMap<String, String>(paramNodes.getLength()); 
        for(int i = 0; i < paramNodes.getLength(); i++) {
        Element param = (Element)paramNodes.item(i);
        params.put(param.getAttribute(GSXML.NAME_ATT), param.getAttribute(GSXML.VALUE_ATT));
        }

        Element response = getResponseAsDOM(fedoraServicesAPIA.query(collection, querytype, params));
        return (Element)response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(0);
    } else {
        logger.error("TextQuery request specified no parameters.\n");
        return this.doc.createElement(GSXML.RESPONSE_ELEM); // empty response
    }
    }

    protected String[] parse(Element request, String nodeType, String attribute) {  
    String[] nodevalues = null;

    Element docList = (Element) GSXML.getChildByTagName(request, nodeType+GSXML.LIST_MODIFIER);
    if (docList != null) {      
        NodeList docNodes = docList.getElementsByTagName(nodeType);
        if(docNodes.getLength() > 0) {
        nodevalues = new String[docNodes.getLength()];
        for(int i = 0; i < nodevalues.length; i++) {
            Element e = (Element)docNodes.item(i);
            nodevalues[i] = e.getAttribute(attribute);
        }
        }
    }
    return nodevalues;
    }


    /** if id ends in .fc, .pc etc, then translate it to the correct id 
     * For now (for testing things work) the default implementation is to just remove the suffix */
    protected String translateId(String id) {
    if (OID.needsTranslating(id)) {
        return OID.translateOID(this, id); //return translateOID(id);
    }
    return id;
    }
    
    /** if an id is not a greenstone id (an external id) then translate 
     * it to a greenstone one 
     * default implementation: return the id. Custom implementation: 
     * the id is a url that maps to a fedorapid whose dc.title contains the required HASHID */
    protected String translateExternalId(String id) {
    //logger.error("*** to translate an external ID: " + id); /////return id;
    return this.externalId2OID(id);
    }

    /** converts an external id to greenstone OID. External ID is a URL link 
     * that, if relative, maps to a fedorapid that has an entry in fedora.
     * The dc:title meta for that fedorapid will contain the required OID. */
    public String externalId2OID(String extid) {
    if(extid.endsWith(".rt") && (extid.indexOf('.') != extid.lastIndexOf('.'))) { 
           // .rt is not file extension, but Greenstone request for root of document
           // not relevant for external ID
           extid = extid.substring(0, extid.length()-3);
    }

       // the following method is unique to FedoraServicesAPIA
    String response = ((FedoraServicesAPIA)fedoraServicesAPIA).getDocIDforURL(extid, this.cluster_name);
    if(response.indexOf(GSXML.ERROR_ELEM) != -1) {
        logger.error("**** The following error occurred when trying to find externalID for ID " + extid);
        logger.error(response);
        return extid;
    }
    if(response.equals("")) {
        return extid;
    } else {
        return response;
    }
    }


  /** translates relative oids into proper oids:
   * .pr (parent), .rt (root) .fc (first child), .lc (last child),
   * .ns (next sibling), .ps (previous sibling) 
   * .np (next page), .pp (previous page) : links sections in the order that you'd read the document
   * a suffix is expected to be present so test before using 
   */
    public String processOID(String doc_id, String top, String suff, int sibling_num) {

    // send off request to get sibling etc. information from Fedora
    Element response = null;
    String[] children = null;
    if(doc_id.startsWith("CL")) { // classifiernode
    response = getResponseAsDOM(fedoraServicesAPIA.retrieveBrowseStructure(this.cluster_name, "ClassifierBrowse", new String[]{doc_id},
                                           new String[]{"children"}, new String[]{"siblingPosition"}));
    NodeList nl = response.getElementsByTagName(GSXML.NODE_STRUCTURE_ELEM);
    if(nl.getLength() > 0) {
        Element nodeStructure = (Element)nl.item(0);

        if(nodeStructure != null) {
        Element root = (Element) GSXML.getChildByTagName(nodeStructure, GSXML.CLASS_NODE_ELEM);
        if(root != null) { // get children
            NodeList classNodes = root.getElementsByTagName(GSXML.CLASS_NODE_ELEM);
            if(classNodes != null) {
            children = new String[classNodes.getLength()];
            for(int i = 0; i < children.length; i++) {
                Element child = (Element)classNodes.item(i);
                children[i] = child.getAttribute(GSXML.NODE_ID_ATT);
            }
            }
        }
        }
    }
    } else { // documentnode
    response = getResponseAsDOM(fedoraServicesAPIA.retrieveDocumentStructure(this.cluster_name, new String[]{doc_id},
                                         new String[]{"children"}, new String[]{"siblingPosition"}));
    String path = GSPath.createPath(new String[]{GSXML.RESPONSE_ELEM, GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER, 
                          GSXML.DOC_NODE_ELEM, GSXML.NODE_STRUCTURE_ELEM, GSXML.DOC_NODE_ELEM});    
    Element parentDocNode = (Element) GSXML.getNodeByPath(response, path);

    if (parentDocNode == null) {
        return top;
    } // else 
    NodeList docNodes = parentDocNode.getElementsByTagName(GSXML.DOC_NODE_ELEM); // only children should remain, since that's what we requested
    if(docNodes.getLength() > 0) {
        children = new String[docNodes.getLength()];
        
        for(int i = 0; i < children.length; i++) {
        Element e = (Element)docNodes.item(i);
        children[i] = e.getAttribute(GSXML.NODE_ID_ATT);
        }
    } else { // return root node
        children = new String[]{doc_id};
    }
    }
    
    if (suff.equals("fc")) {
      return children[0];
    } else if (suff.equals("lc")) {
      return children[children.length-1];
    } else {
      if (suff.equals("ss")) {
    return children[sibling_num-1];
      }
      // find the position that we are at.
      int i=0;
      while(i<children.length) {
    if (children[i].equals(top)) {
      break;
    }
    i++;
      }
        
      if (suff.equals("ns")) {
    if (i==children.length-1) {
      return children[i];
    }
    return children[i+1];
      } else if (suff.equals("ps")) {
    if (i==0) {
      return children[i];
    }
    return children[i-1];
      }
    }

    return top;
  }


    protected Element getResponseAsDOM(String response) {
    if(response == null) { // will not be the case, because an empty  
        return null;    // response message will be sent instead
    }

    Element message = null;     
    try{
        // turn the String xml response into a DOM tree:    
        DocumentBuilder builder 
        = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document doc 
        = builder.parse(new InputSource(new StringReader(response)));
        message = doc.getDocumentElement();
    } catch(Exception e){
        if(response == null) {
        response = "";
        }
        logger.error("An error occurred while trying to parse the response: ");
        logger.error(response);
        logger.error(e.getMessage());
    }
    
    // Error elements in message will be processed outside of here, just return the message
    return message;
    }

    /* //process method for stylesheet requests    
    protected Element processFormat(Element request) {} */
    
    /* returns the service list for the subclass */
    /* protected Element getServiceList(String lang) {
    // for now, it is static and has no language stuff
    return (Element) this.short_service_info.cloneNode(true);
    }*/

    /** returns a specific service description */
    protected Element getServiceDescription(String service, String lang, String subset) {
    if(!lang.equals(prevLanguage)) {
        prevLanguage = lang;
        fedoraServicesAPIA.setLanguage(lang);
    }
    String serviceResponse = fedoraServicesAPIA.describeService(service);
    Element response = getResponseAsDOM(serviceResponse);

    // should be no chance of an npe, since FedoraGS3 lists the services, so will have descriptions for each
    Element e = (Element)response.getElementsByTagName(GSXML.SERVICE_ELEM).item(0);
    e = (Element)this.doc.importNode(e, true);
    return e; 
    }

    /** overloaded version for no args case */
    protected String getTextString(String key, String lang) {
    return getTextString(key, lang, null, null);
    }

    protected String getTextString(String key, String lang, String dictionary) {
    return getTextString(key, lang, dictionary, null);
    }
    protected String getTextString(String key, String lang, String [] args) {
    return getTextString(key, lang, null, args);
    }
    
    /** getTextString - retrieves a language specific text string for the given
key and locale, from the specified resource_bundle (dictionary)
    */
    protected String getTextString(String key, String lang, String dictionary, String[] args) {

    // we want to use the collection class loader in case there are coll specific files
    if (dictionary != null) {
        // just try the one specified dictionary
        Dictionary dict = new Dictionary(dictionary, lang, this.class_loader);
        String result = dict.get(key, args);
        if (result == null) { // not found
        return "_"+key+"_";
        }
        return result;
    }

    // now we try class names for dictionary names
    String class_name = this.getClass().getName();
    class_name = class_name.substring(class_name.lastIndexOf('.')+1);
    Dictionary dict = new Dictionary(class_name, lang, this.class_loader);
    String result = dict.get(key, args);
    if (result != null) {
        return result;
    }

    // we have to try super classes
    Class c = this.getClass().getSuperclass();
    while (result == null && c != null) {
        class_name = c.getName();
        class_name = class_name.substring(class_name.lastIndexOf('.')+1);
        if (class_name.equals("ServiceRack")) {
        // this is as far as we go
        break;
        }
        dict = new Dictionary(class_name, lang, this.class_loader);
        result = dict.get(key, args);
        c = c.getSuperclass();
    }
    if (result == null) {
        return "_"+key+"_";
    }
    return result;
    
    }

    protected String getMetadataNameText(String key, String lang) {

    String properties_name = "metadata_names";
    Dictionary dict = new Dictionary(properties_name, lang);
    
    String result = dict.get(key);
    if (result == null) { // not found
        return null;
    } 
    return result;
    }
}