Metacat

/**

 *  '$RCSfile$'

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

 *              National Center for Ecological Analysis and Synthesis

 *

 *   '$Author: Serhan AKIN $'

 *     '$Date: 2009-07-15 10:54:27 +0300  $'

 *

 * 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.client.rest;

import java.io.BufferedReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.io.Reader;

import java.io.StringReader;

import java.io.Writer;

import java.net.HttpURLConnection;

import java.net.URL;

import java.net.URLConnection;

import java.util.Vector;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import edu.ucsb.nceas.metacat.client.DocumentNotFoundException;

import edu.ucsb.nceas.metacat.client.InsufficientKarmaException;

import edu.ucsb.nceas.metacat.client.MetacatAuthException;

import edu.ucsb.nceas.metacat.client.MetacatException;

import edu.ucsb.nceas.metacat.client.MetacatInaccessibleException;

import edu.ucsb.nceas.utilities.IOUtil;

import edu.ucsb.nceas.utilities.XMLUtilities;

public class MetacatRestClient implements MetacatRest {

	/** The session identifier for the session */

	private String sessionId;

	/** The URL string for the metacat REST API*/

	private String contextRootUrl;

    /**

     * Constructor to create a new instance. 

     */ 

	public MetacatRestClient(String contextRootUrl){

		setContextRootUrl(contextRootUrl);

	}

    /**

     *  Method used to log in to a metacat server through REST API. Implementations will need

     *  to cache a cookie value to make the session persistent.  Each time a

     *  call is made to one of the other methods (e.g., read), the cookie will

     *  need to be passed back to the metacat server along with the request.

     *

     *  @param username   the username of the user, like an LDAP DN

     *  @param password   the password for that user for authentication

     *  @return the response string from metacat in XML format

     *  @throws MetacatAuthException when the username/password could

     *                    not be authenticated

     */

	public String login(String username, String password)

	throws MetacatAuthException, MetacatInaccessibleException {

	    String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_LOGIN;

		String postData = "username="+username+"&password="+password;		

		String response = null;

		try {

			response = sendData(RESOURCE_SESSION, POST, urlParams, postData, "application/x-www-form-urlencoded", null, null);

		} catch (Exception e) {

			throw new MetacatInaccessibleException(e.getMessage());

		}

		if (response.indexOf("<login>") == -1) {

			setSessionId("");

			throw new MetacatAuthException(response);

		} else {

			int start = response.indexOf("<sessionId>") + 11;

			int end = response.indexOf("</sessionId>");

			if ((start != -1) && (end != -1)) {

				setSessionId(response.substring(start,end));

			}

		}

		return response;

	}

    /**

     *  Method used to log out a metacat server. The Metacat server will end

     *  the session when this call is invoked.

     *

     *  @return the response string from metacat in XML format

     *  @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     */

	public String logout()throws MetacatInaccessibleException,MetacatException {

		String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_LOGOUT ;

		String postData = "sessionid="+sessionId;

		String response;

		try {

			response = sendData(RESOURCE_SESSION, POST, urlParams, postData,"application/x-www-form-urlencoded", null, null);

		} catch (Exception e) {

			throw new MetacatInaccessibleException(e.getMessage());

		}

		return response;

	}

    /**

     * Read a public XML document , accessed by docid, and returned as a Reader.

     *

     * @param docid the identifier of the document to be read

     * @param outputFile name of the file to be written to local (optional)

     * @return a Reader for accessing the document

     * @throws InsufficientKarmaException when the user has insufficent rights

     *                                    for the operation

     * @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     * @throws MetacatException when the metacat server generates another error

     */

	public Reader getObject(String docid, String outFile) throws InsufficientKarmaException,

	MetacatInaccessibleException, DocumentNotFoundException, MetacatException{

		String resource = RESOURCE_OBJECTS+"/"+docid; 

		try {

			String response = sendData(resource, GET, null, null, null, null, outFile);

			if (response != null ) {

				if (response != null && response.indexOf("<error>") != -1) {

					if (response.indexOf("does not have permission") != -1) {

						throw new InsufficientKarmaException(response);

					} else if(response.indexOf("does not exist") != -1) {

						throw new DocumentNotFoundException(response);

					} else {

						throw new MetacatException(response);                	

					} 

				} else {

					return new StringReader(response);

				}

			} else 

				throw new MetacatException(response);

		} catch(IOException ioe){

			throw new MetacatInaccessibleException(ioe.getMessage());

		}	

	}

    /**

     * Read XML document from server session, accessed by docid, and returned as a Reader.

     *

     * @param docid the identifier of the document to be read

     * @param outputFile name of the file to be written to local (optional)

     * @return a Reader for accessing the document

     * @throws InsufficientKarmaException when the user has insufficent rights

     *                                    for the operation

     * @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     * @throws MetacatException when the metacat server generates another error

     */ 

	public Reader authenticatedGetObject(String docid, String outFile) throws InsufficientKarmaException,

	MetacatInaccessibleException, DocumentNotFoundException, MetacatException{

		String resource = RESOURCE_OBJECTS+"/"+docid; 

		try {

			String response = sendData(resource, GET, "sessionid="+sessionId, null, null, null, outFile);

			if (response != null ) {

				if (response != null && response.indexOf("<error>") != -1) {

					if (response.indexOf("does not have permission") != -1) {

						throw new InsufficientKarmaException(response);

					} else if(response.indexOf("does not exist") != -1) {

						throw new DocumentNotFoundException(response);

					} else {

						throw new MetacatException(response);                	

					} 

				} else {

					return new StringReader(response);

				}

			} else 

				throw new MetacatException(response);

		} catch(IOException ioe){

			throw new MetacatInaccessibleException(ioe.getMessage());

		}	

	}

    /**

     * Query the metacat document store with the given Ecogrid-compatible

     * query document and return the Ecogrid result set as a Reader.

     *

     * @param xmlQuery a Reader for accessing the XML version of the query

     * @return a Reader for accessing the result set

     */

	public Reader query(Reader xmlQuery) throws MetacatInaccessibleException,IOException {

		String response = null;

		try{	

			response = sendData(RESOURCE_OBJECTS, POST, null, null, "text/xml", xmlQuery, null);

		} catch (Exception e) {

			e.printStackTrace();

			throw new MetacatInaccessibleException(e.getMessage());

		}

		if (response != null)

			return new StringReader(response);

		return null;

	}

    /**

     * Query (as an authenticated user) the metacat document store with the given Ecogrid-compatible

     * query document and return the Ecogrid result set as a Reader.

     *

     * @param xmlQuery a Reader for accessing the XML version of the query

     * @return a Reader for accessing the result set

     */

	public Reader authenticatedQuery(Reader xmlQuery) throws MetacatInaccessibleException,IOException {

		String response = null;

		try{

			response = sendData(RESOURCE_OBJECTS, POST, "sessionid="+sessionId, null, "text/xml", xmlQuery, null);

		} catch (Exception e) {

			e.printStackTrace();

			throw new MetacatInaccessibleException(e.getMessage());

		}

		if (response != null)

			return new StringReader(response);		

		return null;

	}

	/**

     * Create an XML document in the repository.

     *

     * @param docid the docid to insert the document

     * @param xmlDocument a Reader for accessing the XML document to be inserted

     * @param isInsert whether the operation is update or insert

     * 

     * 

     * @return the metacat response message

     * @throws InsufficientKarmaException when the user has insufficent rights

     *                                    for the operation

     * @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     * @throws MetacatException when the metacat server generates another error

     * @throws IOException when there is an error reading the xml document

     */

    public String create(String docid, Reader xmlDocument)

    throws InsufficientKarmaException, MetacatException, IOException, MetacatInaccessibleException {

        return putObject(docid, xmlDocument, true);

    }

    /**

     * Update an XML document in the repository, replacing an existing document.

     *

     * @param docid the docid to insert the document

     * @param xmlDocument a Reader for accessing the XML document to be inserted

     * @param isInsert whether the operation is update or insert

     * 

     * 

     * @return the metacat response message

     * @throws InsufficientKarmaException when the user has insufficent rights

     *                                    for the operation

     * @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     * @throws MetacatException when the metacat server generates another error

     * @throws IOException when there is an error reading the xml document

     */

    public String update(String docid, Reader xmlDocument)

    throws InsufficientKarmaException, MetacatException, IOException, MetacatInaccessibleException {

        return putObject(docid, xmlDocument, false);

    }

	/**

	 * Delete an XML document in the repository.

	 *

	 * @param docid the docid to delete

	 * @return the metacat response message

	 * @throws InsufficientKarmaException when the user has insufficent rights

	 *                                    for the operation

	 * @throws MetacatInaccessibleException when the metacat server can not be

	 *                                    reached or does not respond

	 * @throws MetacatException when the metacat server generates another error

	 */

	public String deleteObject(String docid)

	throws InsufficientKarmaException, MetacatException,MetacatInaccessibleException {

		String resource = RESOURCE_OBJECTS+"/"+docid;

		String urlParams = "sessionid="+sessionId+"&";

		String response = null;

		try{

			response = sendData(resource, DELETE, urlParams, null, null, null, null);

		} catch (Exception e) {

			e.printStackTrace();

			throw new MetacatInaccessibleException(e.getMessage());

		}

		// Check for an error condition

		if (response.indexOf("<error>") != -1) {

			if (response.indexOf("does not have permission") != -1) {

				throw new InsufficientKarmaException(response);

			} else {

				throw new MetacatException(response);

			}

		}	

		return response;

	}

	/**

	 * Return the highest document id for a given scope.  This is used by

	 * clients to make it easier to determine the next free identifier in a

	 * sequence for a given scope.

	 * @param scope String  the scope to use for looking up the latest id

	 * @throws MetacatException when an error occurs

	 */

	public String getNextObject(String scope) throws MetacatException {

		String lastIdentifier = "";

		String resource = RESOURCE_IDENTIFIER;

		String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_GETNEXTOBJ;

		if (scope != null)

			urlParams += "&scope="+scope; 

		String response = null;

		try {

			response = sendData(resource, GET, urlParams, null, null, null, null);

			// Check for an error condition

			if (response.indexOf("<error>") != -1) {

				throw new MetacatException(response);

			} else {

				Reader responseReader = new StringReader(response);

				Node root =

					XMLUtilities.getXMLReaderAsDOMTreeRootNode(responseReader);

				Node docidNode =

					XMLUtilities.getNodeWithXPath(root, "/lastDocid/docid");

				lastIdentifier = docidNode.getFirstChild().getNodeValue();

			}

		} catch (Exception e) {

			throw new MetacatException(e.getMessage());

		}

		return lastIdentifier;

	}

	/**

	 * The method will return the latest revision in metacat server

	 * for a given document id. If some error happens, this method will throw

	 * an exception.

	 * @param identifierId String  the given docid you want to use. the docid it self

	 *                      can have or haven't revision number

	 * @throws MetacatException

	 */

	public int getNextRevision(String identifierId) throws MetacatException {

		int rev = 0;

		String resource = RESOURCE_IDENTIFIER+"/"+identifierId;

		String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_GETNEXTREV;

		String response = null;

		try {

			response = sendData(resource, GET, urlParams, null, null, null, null);

	         // Check for an error condition            

            if (response.indexOf("<error>") != -1 ) {

                throw new MetacatException(response);

            }

			Reader responseReader = new StringReader(response);

			Node root =

				XMLUtilities.getXMLReaderAsDOMTreeRootNode(responseReader);

			Node docidNode =

				XMLUtilities.getNodeWithXPath(root, "/next-revision");

			rev = Integer.parseInt(docidNode.getFirstChild().getNodeValue());                        

		} catch (Exception e) {

			e.printStackTrace();

			throw new MetacatException(e.getMessage());

		}

		return rev;

	}

	/**

	 * return a list of all docids that match a given scope.  if scope is null

	 * return all docids registered in the system

	 * @param scope String  the scope to use to limit the docid query

	 * @throws MetacatException when an error occurs

	 */

	public Vector<String> getAllDocids(String scope) throws MetacatException {

		Vector<String> resultVec = new Vector<String>();

		String resource = RESOURCE_IDENTIFIER;

		String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_GETALLDOCS;

		if (scope != null)

			urlParams += "&scope="+scope; 

		String response = null;

		try {

			response = sendData(resource, GET, urlParams, null, null, null, null);

			// Check for an error condition

			if (response.indexOf("<error>") != -1) {

				throw new MetacatException(response);

			} else {

				Reader responseReader = new StringReader(response);

				Node root =

					XMLUtilities.getXMLReaderAsDOMTreeRootNode(responseReader);

				NodeList nlist = root.getChildNodes();

				for(int i=0; i<nlist.getLength(); i++) {

					Node n = nlist.item(i);

					if(n.getNodeName().equals("docid")) {

						//add the content to the return vector

						String nodeVal = n.getFirstChild().getNodeValue();

						resultVec.addElement(nodeVal);

					}

				}

			}

		} catch (Exception e) {

			throw new MetacatException(e.getMessage());

		}

		return resultVec;

	}

	/**

	 * return true of the given docid is registered, false if not

	 * @param scope String  the scope to use to limit the docid query

	 * @throws MetacatException when an error occurs

	 */

	public boolean isRegistered(String identifierId) throws MetacatException {

		String resource = RESOURCE_IDENTIFIER+"/"+identifierId;

		String urlParams = FUNCTION_KEYWORD+"="+FUNCTION_NAME_ISREGISTERED;

		String response = null;

		try {

			response = sendData(resource, GET, urlParams, null, null, null, null);

			// Check for an error condition

			if (response.indexOf("<error>") != -1) {

				throw new MetacatException(response);

			} else {

				Reader responseReader = new StringReader(response);

				StringBuffer sb = new StringBuffer();

				char[] c = new char[1024];

				int numread = responseReader.read(c, 0, 1024);

				while(numread != -1) {

					sb.append(new String(c, 0, numread));

					numread = responseReader.read(c, 0, 1024);

				}

				String responseStr = sb.toString();

				if(responseStr.indexOf("true") != -1) {

					return true;

				}

				return false;

			}

		} catch (Exception e) {

			throw new MetacatException(e.getMessage());

		}

	}

	/**

	 * Adds identifierId

	 * @param identifierId String  the given docid you want to use.

	 * @throws MetacatException when an error occurs

	 */

	public String addLSID(String identifierId) throws MetacatException {

		String resource = RESOURCE_IDENTIFIER+"/"+identifierId;

		String response = null;

		try {

			response = sendData(resource, PUT, null, null, null, null, null);

		} catch (Exception e) {

			throw new MetacatException(e.getMessage());

		}	

		return response;

	}

	public void setContextRootUrl(String contextRootUrl) {

		if (!contextRootUrl.endsWith("/"))

			contextRootUrl += "/";

		this.contextRootUrl = contextRootUrl;

	}

	public String getSessionId() {

		return sessionId;

	}

	public void setSessionId(String sessionId) {

		this.sessionId = sessionId;

	}

	/**

     * Put (Insert/Update) an XML document into the repository.

     *

     * @param docid the docid to insert the document

     * @param xmlDocument a Reader for accessing the XML document to be inserted

     * @param isInsert whether the operation is update or insert

     * 

     * @return the metacat response message

     * @throws InsufficientKarmaException when the user has insufficent rights

     *                                    for the operation

     * @throws MetacatInaccessibleException when the metacat server can not be

     *                                    reached or does not respond

     * @throws MetacatException when the metacat server generates another error

     * @throws IOException when there is an error reading the xml document

     */

    private String putObject(String docid, Reader xmlDocument, boolean isInsert)

    throws InsufficientKarmaException, MetacatException, IOException, MetacatInaccessibleException {

    	String resource = RESOURCE_OBJECTS+"/"+docid;

    	String urlParams = "sessionid="+sessionId+"&";

    	if (isInsert)

    		urlParams += FUNCTION_KEYWORD+"="+FUNCTION_NAME_INSERT;

    	else

    		urlParams += FUNCTION_KEYWORD+"="+FUNCTION_NAME_UPDATE;

    	String response = null;

    	try{

    		response = sendData(resource, PUT, urlParams, null, "text/xml", xmlDocument, null);

    	} catch (Exception e) {

    		e.printStackTrace();

    		throw new MetacatInaccessibleException(e.getMessage());

    	}

    	// Check for an error condition

    	if (response.indexOf("<error>") != -1) {

    		if (response.indexOf("does not have permission") != -1) {

    			throw new InsufficientKarmaException(response);

    		} else {

    			throw new MetacatException(response);

    		}

    	}	

    	return response;

    }

    /**

	 * Send request to metacat REST API. 

	 * @param resource Resource name to be accessed

	 * @param method HTTP verb, shoudl be one of GET,POST,DELETE,PUT

	 * @param urlParameters QueryString to be added to the end of server url

	 * @param postData QueryString to be printed to output stream

	 * @param contentType Content Type of the data to be posted. eg: "text/xml" or "application/x-www-form-urlencoded"

	 * @param postFileReader Reader of file to be posted

	 * @param outputFile File name to be saved returning from API

	 */

	private String sendData(String resource, String method, String urlParamaters,String postData, String contentType,

			Reader postFileReader, String outputFile) throws IOException {

		HttpURLConnection connection = null ;

		String restURL = contextRootUrl+resource;

		if (urlParamaters != null) {

			if (restURL.indexOf("?") == -1)				

				restURL += "?";

			restURL += urlParamaters; 

		}

		URL u = new URL(restURL);

		URLConnection uc = u.openConnection();

		connection= (HttpURLConnection) uc;

		if (contentType!=null)

			connection.setRequestProperty("Content-Type",contentType);

		connection.setDoOutput(true);

		connection.setDoInput(true);

		connection.setRequestMethod(method);

		if (!method.equals(GET)) {

			if (postFileReader != null) {

				postData = IOUtil.getAsString(postFileReader, true);

			}

			if (postData != null){

				OutputStream out = connection.getOutputStream();

				Writer wout = new OutputStreamWriter(out);		

				wout.write(postData); 

				wout.flush();

				wout.close();

			}			

		}

		return readStream(connection.getInputStream(),outputFile);

	}

	/**

	 * 

	 * Reads Input stream and return readed data, optionaly write the data to specified file 

	 * */

	private String readStream(InputStream is, String writeFile) throws IOException{

		BufferedReader in = new BufferedReader(

				new InputStreamReader(

						is));

		String inputLine;

		StringBuffer b = new StringBuffer();

		FileWriter writer = null;

		if (writeFile!=null)

			writer =  new FileWriter(writeFile);

		while ((inputLine = in.readLine()) != null) { 

			//System.out.println(inputLine+"\n");

			b.append(inputLine+"\n");

			if (writeFile!=null)

				writer.write(inputLine);

		}

		if (writeFile!=null) {

			writer.flush();

			writer.close();			

		}

		in.close();

		return b.toString();

	}

}