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/**
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* '$RCSfile$'
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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*
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* '$Author: jones $'
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* '$Date: 2003-09-22 13:14:39 -0700 (Mon, 22 Sep 2003) $'
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* '$Revision: 1828 $'
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package edu.ucsb.nceas.metacat.client;
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import java.io.BufferedReader;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.PushbackReader;
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import java.io.IOException;
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import java.io.StringWriter;
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import java.io.Reader;
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import java.net.URL;
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import java.util.Properties;
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import edu.ucsb.nceas.utilities.HttpMessage;
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import edu.ucsb.nceas.utilities.IOUtil;
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/**
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* This interface provides methods for initializing and logging in to a
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* Metacat server, and then querying, reading, transforming, inserting,
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* updating and deleting documents from that server.
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*/
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public class MetacatClient implements Metacat
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{
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/** The URL string for the metacat server */
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private String metacatUrl;
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/** The session identifier for the session */
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private String sessionId;
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/**
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* Constructor to create a new instance. Protected because instances
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* should only be created by the factory MetacatFactory.
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*/
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protected MetacatClient()
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{
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this.metacatUrl = null;
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this.sessionId = null;
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}
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/**
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* Method used to log in to a metacat server. Implementations will need
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* to cache a cookie value to make the session persistent. Each time a
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* call is made to one of the other methods (e.g., read), the cookie will
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* need to be passed back to the metacat server along with the request.
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*
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* @param username the username of the user, like an LDAP DN
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* @param password the password for that user for authentication
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* @return the response string from metacat in XML format
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* @throws MetacatAuthException when the username/password could
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* not be authenticated
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*/
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public String login(String username, String password)
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throws MetacatAuthException, MetacatInaccessibleException
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{
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Properties prop = new Properties();
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prop.put("action", "login");
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prop.put("qformat", "xml");
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prop.put("username", username);
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prop.put("password", password);
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String response = null;
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try {
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response = sendDataForString(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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if (response.indexOf("<login>") == -1) {
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setSessionId("");
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throw new MetacatAuthException(response);
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} else {
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int start = response.indexOf("<sessionId>") + 11;
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int end = response.indexOf("</sessionId>");
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if ((start != -1) && (end != -1)) {
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setSessionId(response.substring(start,end));
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}
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}
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return response;
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}
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/**
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* Method used to log out a metacat server. The Metacat server will end
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* the session when this call is invoked.
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*
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* @return the response string from metacat in XML format
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* @throws MetacatInaccessibleException when the metacat server can not be
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* reached or does not respond
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*/
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public String logout() throws MetacatInaccessibleException, MetacatException
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{
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Properties prop = new Properties();
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prop.put("action", "logout");
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prop.put("qformat", "xml");
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String response = null;
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try {
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response = sendDataForString(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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if (response.indexOf("<logout>") == -1) {
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throw new MetacatException(response);
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}
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setSessionId("");
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return response;
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}
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/**
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* Read an XML document from the metacat server session, accessed by docid,
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* and returned as a Reader.
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*
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* @param docid the identifier of the document to be read
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* @return a Reader for accessing the document
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* @throws InsufficientKarmaException when the user has insufficent rights
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* for the operation
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* @throws MetacatInaccessibleException when the metacat server can not be
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* reached or does not respond
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* @throws MetacatException when the metacat server generates another error
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*/
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public Reader read(String docid) throws InsufficientKarmaException,
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MetacatInaccessibleException, MetacatException
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{
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PushbackReader pbr = null;
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Properties prop = new Properties();
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prop.put("action", "read");
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prop.put("qformat", "xml");
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prop.put("docid", docid);
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InputStream response = null;
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try {
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response = sendData(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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pbr = new PushbackReader(new InputStreamReader(response), 512);
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try {
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char[] characters = new char[512];
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int len = pbr.read(characters, 0, 512);
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StringWriter sw = new StringWriter();
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sw.write(characters, 0, len);
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String message = sw.toString();
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sw.close();
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pbr.unread(characters, 0, len);
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if (message.indexOf("<error>") != -1) {
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if (message.indexOf("does not have permission") != -1) {
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throw new InsufficientKarmaException(message);
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} else {
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throw new MetacatException(message);
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}
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}
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} catch (IOException ioe) {
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throw new MetacatException(
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"MetacatClient: Error converting Reader to String."
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+ ioe.getMessage());
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}
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return pbr;
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}
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/**
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* Query the metacat document store with the given metacat-compatible
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* query document, and return the result set as a Reader.
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*
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* @param xmlQuery a Reader for accessing the XML version of the query
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* @return a Reader for accessing the result set
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*/
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public Reader query(Reader xmlQuery) throws MetacatInaccessibleException,
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IOException
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{
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Reader reader = null;
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String query = null;
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try {
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query = IOUtil.getAsString(xmlQuery, true);
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} catch (IOException ioE) {
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throw ioE;
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}
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//set up properties
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Properties prop = new Properties();
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prop.put("action", "squery");
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prop.put("qformat", "xml");
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prop.put("query", query);
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InputStream response = null;
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try {
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response = sendData(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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reader = new InputStreamReader(response);
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return reader;
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}
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/**
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* Insert an XML document into the repository.
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*
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* @param docid the docid to insert the document
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* @param xmlDocument a Reader for accessing the XML document to be inserted
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* @param schema a Reader for accessing the DTD or XML Schema for
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* the document
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* @return the metacat response message
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* @throws InsufficientKarmaException when the user has insufficent rights
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* for the operation
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* @throws MetacatInaccessibleException when the metacat server can not be
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* reached or does not respond
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* @throws MetacatException when the metacat server generates another error
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* @throws IOException when there is an error reading the xml document
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*/
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public String insert(String docid, Reader xmlDocument, Reader schema)
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throws InsufficientKarmaException, MetacatException, IOException,
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MetacatInaccessibleException
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{
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Reader reader = null;
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String doctext = null;
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String schematext = null;
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try {
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doctext = IOUtil.getAsString(xmlDocument, true);
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if (schema != null) {
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schematext = IOUtil.getAsString(schema, true);
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}
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} catch (IOException ioE) {
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throw ioE;
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}
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//set up properties
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Properties prop = new Properties();
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prop.put("action", "insert");
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prop.put("docid", docid);
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prop.put("doctext", doctext);
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if (schematext != null) {
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prop.put("dtdtext", schematext);
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}
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String response = null;
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try {
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response = sendDataForString(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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// Check for an error condition
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if (response.indexOf("<error>") != -1) {
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if (response.indexOf("does not have permission") != -1) {
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throw new InsufficientKarmaException(response);
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} else {
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throw new MetacatException(response);
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}
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}
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return response;
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}
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/**
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* Update an XML document in the repository.
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*
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* @param docid the docid to update
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* @param xmlDocument a Reader for accessing the XML text to be updated
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* @param schema a Reader for accessing the DTD or XML Schema for
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* the document
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* @return the metacat response message
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* @throws InsufficientKarmaException when the user has insufficent rights
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* for the operation
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* @throws MetacatInaccessibleException when the metacat server can not be
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* reached or does not respond
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* @throws MetacatException when the metacat server generates another error
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* @throws IOException when there is an error reading the xml document
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*/
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public String update(String docid, Reader xmlDocument, Reader schema)
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throws InsufficientKarmaException, MetacatException, IOException,
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MetacatInaccessibleException
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{
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Reader reader = null;
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String doctext = null;
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String schematext = null;
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try {
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doctext = IOUtil.getAsString(xmlDocument, true);
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if (schema != null) {
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schematext = IOUtil.getAsString(schema, true);
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}
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} catch (IOException ioE) {
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throw ioE;
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}
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//set up properties
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Properties prop = new Properties();
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prop.put("action", "update");
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prop.put("docid", docid);
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prop.put("doctext", doctext);
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if (schematext != null) {
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prop.put("dtdtext", schematext);
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}
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String response = null;
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try {
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response = sendDataForString(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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// Check for an error condition
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if (response.indexOf("<error>") != -1) {
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if (response.indexOf("does not have permission") != -1) {
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throw new InsufficientKarmaException(response);
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} else {
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throw new MetacatException(response);
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}
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}
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return response;
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}
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/**
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* Delete an XML document in the repository.
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*
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* @param docid the docid to delete
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* @return the metacat response message
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* @throws InsufficientKarmaException when the user has insufficent rights
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* for the operation
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* @throws MetacatInaccessibleException when the metacat server can not be
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* reached or does not respond
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* @throws MetacatException when the metacat server generates another error
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*/
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public String delete(String docid)
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throws InsufficientKarmaException, MetacatException,
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MetacatInaccessibleException
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{
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//set up properties
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Properties prop = new Properties();
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prop.put("action", "delete");
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prop.put("docid", docid);
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String response = null;
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try {
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response = sendDataForString(prop);
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} catch (Exception e) {
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throw new MetacatInaccessibleException(e.getMessage());
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}
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|
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// Check for an error condition
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if (response.indexOf("<error>") != -1) {
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if (response.indexOf("does not have permission") != -1) {
|
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throw new InsufficientKarmaException(response);
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} else {
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throw new MetacatException(response);
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}
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374
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}
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375
|
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return response;
|
377
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}
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378
|
|
379
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/**
|
380
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* When the MetacatFactory creates an instance it needs to set the
|
381
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* MetacatUrl to which connections should be made.
|
382
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*
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383
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* @param metacatUrl the URL for the metacat server
|
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*/
|
385
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public void setMetacatUrl(String metacatUrl)
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{
|
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this.metacatUrl = metacatUrl;
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388
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}
|
389
|
|
390
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/**
|
391
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* Get the session identifier for this session. This is only valid if
|
392
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* the login methods has been called successfully for this Metacat object
|
393
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* beforehand.
|
394
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*
|
395
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* @returns the sessionId as a String, or null if the session is invalid
|
396
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*/
|
397
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public String getSessionId()
|
398
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{
|
399
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return this.sessionId;
|
400
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}
|
401
|
|
402
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/**
|
403
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* Set the session identifier for this session. This identifier was
|
404
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* previously established with a call to login. To continue to use the
|
405
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* same session, set the session id before making a call to one of the
|
406
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* metacat access methods (e.g., read, query, insert, etc.).
|
407
|
*
|
408
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* @param String the sessionId from a previously established session
|
409
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*/
|
410
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public void setSessionId(String sessionId)
|
411
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{
|
412
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this.sessionId = sessionId;
|
413
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}
|
414
|
|
415
|
/************************************************************************
|
416
|
* PRIVATE METHODS
|
417
|
************************************************************************/
|
418
|
|
419
|
/**
|
420
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* Send a request to metacat.
|
421
|
*
|
422
|
* @param prop the properties to be URL encoded and sent
|
423
|
*/
|
424
|
synchronized private InputStream sendDataOnce(Properties prop)
|
425
|
throws Exception
|
426
|
{
|
427
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InputStream returnStream = null;
|
428
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URL url = new URL(metacatUrl);
|
429
|
HttpMessage msg = new HttpMessage(url);
|
430
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msg.setCookie("JSESSIONID="+this.sessionId);
|
431
|
returnStream = msg.sendPostData(prop);
|
432
|
return returnStream;
|
433
|
}
|
434
|
|
435
|
/**
|
436
|
* Send a request to Metacat
|
437
|
*
|
438
|
* @param prop the properties to be sent to Metacat
|
439
|
* @return InputStream as returned by Metacat
|
440
|
*/
|
441
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synchronized private InputStream sendData(Properties prop) throws Exception
|
442
|
{
|
443
|
InputStream returnStream = null;
|
444
|
|
445
|
/*
|
446
|
Note: The reason that there are three try statements all executing
|
447
|
the same code is that there is a problem with the initial connection
|
448
|
using the HTTPClient protocol handler. These try statements make
|
449
|
sure that a connection is made because it gives each connection a
|
450
|
2nd and 3rd chance to work before throwing an error.
|
451
|
THIS IS A TOTAL HACK. THIS NEEDS TO BE LOOKED INTO AFTER THE BETA1
|
452
|
RELEASE OF MORPHO!!! cwb (7/24/01)
|
453
|
*/
|
454
|
try {
|
455
|
return sendDataOnce(prop);
|
456
|
} catch (Exception e) {
|
457
|
try {
|
458
|
return sendDataOnce(prop);
|
459
|
} catch (Exception e2) {
|
460
|
try {
|
461
|
return sendDataOnce(prop);
|
462
|
} catch (Exception e3) {
|
463
|
System.err.println(
|
464
|
"Failed to send data to metacat 3 times.");
|
465
|
throw e3;
|
466
|
}
|
467
|
}
|
468
|
}
|
469
|
}
|
470
|
|
471
|
/**
|
472
|
* Send a request to Metacat
|
473
|
*
|
474
|
* @param prop the properties to be sent to Metacat
|
475
|
* @return a string as returned by Metacat
|
476
|
*/
|
477
|
synchronized private String sendDataForString(Properties prop)
|
478
|
throws Exception
|
479
|
{
|
480
|
String response = null;
|
481
|
|
482
|
try {
|
483
|
InputStreamReader returnStream =
|
484
|
new InputStreamReader(sendData(prop));
|
485
|
StringWriter sw = new StringWriter();
|
486
|
int len;
|
487
|
char[] characters = new char[512];
|
488
|
while ((len = returnStream.read(characters, 0, 512)) != -1) {
|
489
|
sw.write(characters, 0, len);
|
490
|
}
|
491
|
returnStream.close();
|
492
|
response = sw.toString();
|
493
|
sw.close();
|
494
|
} catch (Exception e) {
|
495
|
throw e;
|
496
|
}
|
497
|
return response;
|
498
|
}
|
499
|
}
|