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/**
* Copyright 2006 OCLC, Online Computer Library Center Licensed under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License. You may obtain a copy of the
* License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is
* distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and limitations under the License.
*/
package org.oclc.oai.harvester2.verb;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Date;
import java.util.zip.GZIPInputStream;
import java.util.zip.InflaterInputStream;
import java.util.zip.ZipInputStream;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
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.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
//import org.apache.xpath.XPathAPI;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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;
/**
* HarvesterVerb is the parent class for each of the OAI verbs.
*
* @author Jefffrey A. Young, OCLC Online Computer Library Center
*/
public abstract class HarvesterVerb {
private static final Logger log = LoggerFactory.getLogger(HarvesterVerb.class);
/* Primary OAI namespaces */
public static final String SCHEMA_LOCATION_V2_0 = "http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd";
public static final String SCHEMA_LOCATION_V1_1_GET_RECORD = "http://www.openarchives.org/OAI/1.1/OAI_GetRecord http://www.openarchives.org/OAI/1.1/OAI_GetRecord.xsd";
public static final String SCHEMA_LOCATION_V1_1_IDENTIFY = "http://www.openarchives.org/OAI/1.1/OAI_Identify http://www.openarchives.org/OAI/1.1/OAI_Identify.xsd";
public static final String SCHEMA_LOCATION_V1_1_LIST_IDENTIFIERS = "http://www.openarchives.org/OAI/1.1/OAI_ListIdentifiers http://www.openarchives.org/OAI/1.1/OAI_ListIdentifiers.xsd";
public static final String SCHEMA_LOCATION_V1_1_LIST_METADATA_FORMATS = "http://www.openarchives.org/OAI/1.1/OAI_ListMetadataFormats http://www.openarchives.org/OAI/1.1/OAI_ListMetadataFormats.xsd";
public static final String SCHEMA_LOCATION_V1_1_LIST_RECORDS = "http://www.openarchives.org/OAI/1.1/OAI_ListRecords http://www.openarchives.org/OAI/1.1/OAI_ListRecords.xsd";
public static final String SCHEMA_LOCATION_V1_1_LIST_SETS = "http://www.openarchives.org/OAI/1.1/OAI_ListSets http://www.openarchives.org/OAI/1.1/OAI_ListSets.xsd";
private Document doc = null;
private String schemaLocation = null;
private String requestURL = null;
private static final ThreadLocal builderFactory = new ThreadLocal() {
@Override
public DocumentBuilderFactory initialValue() {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
return factory;
}
};
private static final ThreadLocal transformerFactory = new ThreadLocal() {
@Override
public TransformerFactory initialValue() {
return TransformerFactory.newInstance();
}
};
private static final ThreadLocal xpath = new ThreadLocal() {
@Override
public XPath initialValue() {
XPathFactory fucktory = XPathFactory.newInstance();
XPath xpath = fucktory.newXPath();
try {
xpath.setNamespaceContext(new OAINamespaceContext(builderFactory.get()));
} catch (ParserConfigurationException e) {
log.error("Cannot set namespace context", e);
}
return xpath;
}
};
/**
* Get the OAI response as a DOM object
*
* @return the DOM for the OAI response
*/
public Document getDocument() {
return doc;
}
/**
* Get the xsi:schemaLocation for the OAI response
*
* @return the xsi:schemaLocation value
*/
public String getSchemaLocation() {
return schemaLocation;
}
/**
* Get the OAI errors
*
* @return a NodeList of /oai:OAI-PMH/oai:error elements
* @throws XPathExpressionException
*/
public NodeList getErrors() throws XPathExpressionException {
if (SCHEMA_LOCATION_V2_0.equals(getSchemaLocation())) {
return getNodeList("/oai20:OAI-PMH/oai20:error");
} else {
return null;
}
}
/**
* Get the OAI request URL for this response
*
* @return the OAI request URL as a String
*/
public String getRequestURL() {
return requestURL;
}
/**
* Mock object creator (for unit testing purposes)
*/
public HarvesterVerb() {
}
/**
* Performs the OAI request
*
* @param requestURL
* @throws IOException
* @throws ParserConfigurationException
* @throws SAXException
* @throws XPathExpressionException
*/
public HarvesterVerb(String requestURL) throws IOException,
ParserConfigurationException, SAXException, XPathExpressionException {
harvest(requestURL);
}
/**
* Preforms the OAI request
*
* @param requestURL
* @throws IOException
* @throws ParserConfigurationException
* @throws SAXException
* @throws XPathExpressionException
*/
private void harvest(String requestURL) throws IOException,
ParserConfigurationException, SAXException, XPathExpressionException {
this.requestURL = requestURL;
log.debug("requestURL=" + requestURL);
InputStream in;
URL url = new URL(requestURL);
HttpURLConnection con = null;
int responseCode;
do {
con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("User-Agent", "OAIHarvester/2.0");
con.setRequestProperty("Accept-Encoding",
"compress, gzip, identify");
try {
responseCode = con.getResponseCode();
log.debug("responseCode=" + responseCode);
} catch (FileNotFoundException e) {
// assume it's a 503 response
log.info(requestURL, e);
responseCode = HttpURLConnection.HTTP_UNAVAILABLE;
}
if (responseCode == HttpURLConnection.HTTP_UNAVAILABLE) {
long retrySeconds = con.getHeaderFieldInt("Retry-After", -1);
if (retrySeconds == -1) {
long now = (new Date()).getTime();
long retryDate = con.getHeaderFieldDate("Retry-After", now);
retrySeconds = retryDate - now;
}
if (retrySeconds == 0) { // Apparently, it's a bad URL
throw new FileNotFoundException("Bad URL?");
}
System.err.println("Server response: Retry-After=" + retrySeconds);
if (retrySeconds > 0) {
try {
Thread.sleep(retrySeconds * 1000);
} catch (InterruptedException ex) {
log.error("Error while sleeping", ex);
}
}
}
} while (responseCode == HttpURLConnection.HTTP_UNAVAILABLE);
String contentEncoding = con.getHeaderField("Content-Encoding");
log.debug("contentEncoding=" + contentEncoding);
if ("compress".equals(contentEncoding)) {
ZipInputStream zis = new ZipInputStream(con.getInputStream());
zis.getNextEntry();
in = zis;
} else if ("gzip".equals(contentEncoding)) {
in = new GZIPInputStream(con.getInputStream());
} else if ("deflate".equals(contentEncoding)) {
in = new InflaterInputStream(con.getInputStream());
} else {
in = con.getInputStream();
}
InputSource data = new InputSource(in);
doc = builderFactory.get().newDocumentBuilder().parse(data);
// The URIs in xsi:schemaLocation are separated by (any kind
// of) white space. Normalize it to a single space.
String schemaLoc = getSingleString("/*/@xsi:schemaLocation");
this.schemaLocation = schemaLoc.trim().replaceAll("\\s+", " ");
}
/**
* Get the String value for the given XPath location in the response DOM
*
* @param xpath
* @return a String containing the value of the XPath location.
* @throws XPathExpressionException
*/
public String getSingleString(String xpath) throws XPathExpressionException {
return getSingleString(getDocument(), xpath);
// return XPathAPI.eval(getDocument(), xpath, namespaceElement).str();
// String str = null;
// Node node = XPathAPI.selectSingleNode(getDocument(), xpath,
// namespaceElement);
// if (node != null) {
// XObject xObject = XPathAPI.eval(node, "string()");
// str = xObject.str();
// }
// return str;
}
public String getSingleString(Node node, String expression) throws XPathExpressionException {
return xpath.get().evaluate(expression, node);
}
/**
* Get a NodeList containing the nodes in the response DOM for the specified xpath
*
* @param expression
* @return the NodeList for the xpath into the response DOM
* @throws XPathExpressionException
*/
public NodeList getNodeList(String expression) throws XPathExpressionException {
return (NodeList) xpath.get().evaluate(expression, getDocument(), XPathConstants.NODESET);
}
@Override
public String toString() {
// Element docEl = getDocument().getDocumentElement();
// return docEl.toString();
Source input = new DOMSource(getDocument());
StringWriter sw = new StringWriter();
Result output = new StreamResult(sw);
try {
Transformer idTransformer = transformerFactory.get().newTransformer();
idTransformer.setOutputProperty(
OutputKeys.OMIT_XML_DECLARATION, "yes");
idTransformer.transform(input, output);
return sw.toString();
} catch (TransformerException e) {
return e.getMessage();
}
}
}
