source: MDService2/branches/MDService_simple/src/eu/clarin/cmdi/mdservice/action/Pz2ProxyAction.java @ 1509

package eu.clarin.cmdi.mdservice.action;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.HashMap;
import java.io.ByteArrayInputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import eu.clarin.cmdi.mdservice.model.Query;
import eu.clarin.cmdi.mdservice.model.WorkspaceProfile;

/**
 
 */
public class Pz2ProxyAction extends RepoProxyAction {

        private static final long serialVersionUID = 1L;

        private String proxy_key = "pazpar2";
        
        private String command;
        private String query;
        private String sessionID;
        private String sort;
        private String block;
        
        public void setCommand(String command) {
                this.command = command;
        }
        public String getCommand() {
                return command;
        }
        public void setQuery(String query) {
                this.query = query;
        }
        public String getQuery() {
                return query;
        }
        public void setSessionID(String sessionID) {
                this.sessionID = sessionID;
        }
        public String getSessionID() {
                return sessionID;
        }

        public void setSort(String sort) {
                this.sort = sort;
        }
        public String getSort() {
                return sort;
        }
        public void setBlock(String block) {
                this.block = block;
        }
        public String getBlock() {
                return block;
        }
        
        @Override
        protected void  initialize(){
                 super.initialize();
                 this.setActionkey("pazpar2");                          
         }
        
        //TODO cache after analysis
        @Override
        public String getCache() {
                return Cache.SKIP;
        }
        
        public String createURLParams(){
                String params = "?";
                if (!(command == null)){
                        params = params + "command=" + command;
                }
                if (!(sessionID == null)){
                        params = params + "&session=" + sessionID;
                }
                if (!(query == null)){
                        params = params + "&query=" + query;
                }
                if (!(getStartItem() == null)){
                        params = params + "&start=" + getStartItem();
                }
                if (!(getMaximumItems() == null)){
                        params = params + "&num=" + getMaximumItems();
                }
                if (!(sort == null)){
                        params = params + "&sort=" + sort;
                        if (!(block == null)){
                                params = params + ":" + block;
                        }
                }
                
                return params;
        }
        @Override
        public String getBaseURI() {            
                String uri = WorkspaceProfile.getRepositoryPath(getRepository());               
                return uri;
        }
        
        @Override
        public URL getTargetRequest() throws IOException {
        URL targetURL = null;           
                        
                targetURL =new URL( getBaseURL(), createURLParams() );
                Admin.notifyUser("Pz2.targetURL:" + targetURL);
            return targetURL;
        }
        
/**
 * Overrides the default implementation for the case, when the Service shall act as "collector",
 * waiting for the final result (implemented in getSourcePz2
 * The distinction is based on the command parameter: if it is given, the Class(Service) acts as a basic proxy
 * transparently passing the communication between client and target repository.  
 */
        @Override
        public InputStream getSourceStream() throws IOException, NoStylesheetException {
                if (getCommand() == null){
                        try {
                                return getSourcePz2();
                        } catch (Exception e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                        }
                } 
                        
                return super.getSourceStream();
        }
        
/**
 * TODO: move to Utils
 * @param is
 * @return
 */
        public Document getDocument(InputStream is){
                Document doc = null;
                DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder docBuilder;
                try {
                        docBuilder = docFactory.newDocumentBuilder();
                        doc = docBuilder.parse(is);
                } catch (ParserConfigurationException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                } catch (SAXException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                }       
                return doc;
        }
        
/**
 * TODO: move to Utils
 * @param is
 * @param expression
 * @return
 */
        public String getDocumentData(InputStream is, String expression){
                String sessionid = "";
        
                XPathFactory factory = XPathFactory.newInstance(); 
            XPath xpath = factory.newXPath(); 
            XPathExpression expr;
                try {
                        expr = xpath.compile(expression);
                        sessionid = (String) expr.evaluate(getDocument(is), XPathConstants.STRING);
                } catch (XPathExpressionException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                }
                        
                return sessionid;
                
        }

/**
 * This function wraps the session-based communication with a Pazpar2-target, waiting until all the responses were returned (or timeout occured)
 * returning the full result at the end.   
 * @return returns the collected final result as a stream
 * @throws Exception
 */
        public InputStream getSourcePz2() throws Exception {
                
                InputStream is = null;
                // TODO param settings
                //init
                setCommand("init");
                String sessionID = getDocumentData(this.getSourceStream(), "//init/session");
                // get result
                setCommand("search");
                setSessionID(sessionID);
                setQuery(this.getSquery());
                String ok = getDocumentData(this.getSourceStream(),"//search/status");
                
                String activeclients = "1";
                setCommand("show");
                setSort("relevance");
                setBlock("1");
                //TODO timeout  settings
                long startMillis = System.currentTimeMillis();
                long timeout = 0;
                if (this.getWPOption("pazpartimeout") == null){
                        timeout = 1000;
                } else {
                        timeout = Integer.parseInt(this.getWPOption("pazpartimeout"));
                }
                while (Integer.parseInt(activeclients) > 0){
                        //activeclients = getDocumentData(this.getSourceStream(), "//show/activeclients");
                        is = this.getSourceStream();
                        activeclients = getDocumentData(is, "//show/activeclients");
                        Thread.sleep(1000); 
                        Admin.notifyUser("ActiveClients: " + activeclients, Admin.DEBUG);
                        if ((System.currentTimeMillis() - startMillis)/1000 > timeout) {
                                break;
                        }
                }
                is = this.getSourceStream();
                return is;
        }
        
}