/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.oodt.grid;
import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.HashSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
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 org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.SAXException;
import org.apache.oodt.profile.Profile;
import org.apache.oodt.profile.handlers.ProfileHandler;
import org.apache.oodt.xmlquery.QueryElement;
import org.apache.oodt.xmlquery.XMLQuery;
/**
* Profile query servlet handles profile queries. It returns every matching profile from
* every query handler that provides matching profiles. If no handlers are installed,
* then it returns an empty <profiles> document.
*
*/
public class ProfileQueryServlet extends QueryServlet {
/** {@inheritDoc} */
protected List getServers(Configuration config) {
return config.getProfileServers();
}
/** {@inheritDoc} */
protected void handleQuery(XMLQuery query, List handlers, HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException {
// Find if the query should be targeted to specific handlers.
Set ids = new HashSet();
if (query.getFromElementSet() != null) {
for (Iterator i = query.getFromElementSet().iterator(); i.hasNext();) {
QueryElement qe = (QueryElement) i.next();
if ("handler".equals(qe.getRole()) && qe.getValue() != null)
ids.add(qe.getValue());
}
}
res.setContentType("text/xml"); // XML, comin' at ya
res.getWriter().println("<?xml version='1.0' encoding='UTF-8'?>"); // UTF-8 no less. Boo-ya.
res.getWriter().println("<!DOCTYPE profiles PUBLIC '" // Get a doctype in there for the highly ...
+ Profile.PROFILES_DTD_FPI + "' '" // ... anal ...
+ Profile.PROFILES_DTD_URL + "'>"); // ... retentive.
res.getWriter().println("<profiles>"); // Start tag for the whole /sbin/fsck mess
Transformer transformer = null; // Start out w/no transformer and no doc
Document doc = null; // Don't make 'em if we don't need 'em
boolean sentAtLeastOne = false; // Track if we send any profiles at all
Exception exception = null; // And save any exception
for (Iterator i = handlers.iterator(); i.hasNext();) try { // To iterate over each handler
ProfileHandler handler = (ProfileHandler) i.next(); // Get the handler
String id = handler.getID(); // Get the ID, and if targeting to IDs
if (!ids.isEmpty() && !ids.contains(id)) continue; // ... and it's not one we want, skip it.
List results = handler.findProfiles(query); // Have it find profiles
if (results == null) results = Collections.EMPTY_LIST; // Assume nothing
for (Iterator j = results.iterator(); j.hasNext();) { // For each matching profile
Profile profile = (Profile) j.next(); // Get the profile
if (transformer == null) { // No transformer/doc yet?
transformer = createTransformer(); // Then make the transformer
doc = Profile.createProfileDocument(); // And the doc
} // And use the doc ...
Node profileNode = profile.toXML(doc); // To render the profile into XML
DOMSource source = new DOMSource(profileNode); // And the XML becomes is source
StreamResult result = new StreamResult(res.getWriter()); // And the response is a result
transformer.transform(source, result); // And serialize into glorious text
sentAtLeastOne = true; // OK, we got at least one out the doo
}
} catch (Exception ex) { // Uh oh
exception = ex; // OK, just hold onto it for now
}
if (!sentAtLeastOne && exception != null) { // Got none out the door and had an error?
res.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, // Then we can report it.
exception.getMessage());
return;
}
// However, if we get here, we got at least one profile out the door. In
// that case, hide any error that might've occurred from subsequent
// handlers. (Or, if we get here, there were no errors. Yay.)
res.getWriter().println("</profiles>"); // End tag for the whole fsck'n mess
}
/**
* Create a transformer, properly configured for XML text serialization.
*
* @return a <code>Transformer</code> value.
* @throws TransformerException if an error occurs.
*/
private static Transformer createTransformer() throws TransformerException {
Transformer transformer;
synchronized (TRANSFORMER_FACTORY) {
transformer = TRANSFORMER_FACTORY.newTransformer();
}
transformer.setOutputProperty(OutputKeys.METHOD, "xml");
transformer.setOutputProperty(OutputKeys.VERSION, "1.0");
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
transformer.setOutputProperty(OutputKeys.STANDALONE, "no");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.MEDIA_TYPE, "text/xml");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
return transformer;
}
/** Sole transformer factory this class will ever need. */
private static final TransformerFactory TRANSFORMER_FACTORY = TransformerFactory.newInstance();
}