/* The contents of this file are subject to the license and copyright terms
* detailed in the license directory at the root of the source tree (also
* available online at http://fedora-commons.org/license/).
*/
package fedora.server.access;
import java.io.File;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PipedReader;
import java.io.PipedWriter;
import java.net.URLDecoder;
import java.util.Enumeration;
import java.util.Hashtable;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.Templates;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import org.apache.log4j.Logger;
import fedora.common.Constants;
import fedora.server.Context;
import fedora.server.ReadOnlyContext;
import fedora.server.Server;
import fedora.server.errors.GeneralException;
import fedora.server.errors.InitializationException;
import fedora.server.errors.ObjectNotFoundException;
import fedora.server.errors.ObjectNotInLowlevelStorageException;
import fedora.server.errors.ServerException;
import fedora.server.errors.StreamIOException;
import fedora.server.errors.authorization.AuthzException;
import fedora.server.errors.servletExceptionExtensions.BadRequest400Exception;
import fedora.server.errors.servletExceptionExtensions.InternalError500Exception;
import fedora.server.errors.servletExceptionExtensions.NotFound404Exception;
import fedora.server.errors.servletExceptionExtensions.RootException;
import fedora.utilities.XmlTransformUtility;
/**
* Implements the "getObjectHistory" functionality of the Fedora Access LITE
* (API-A-LITE) interface using a java servlet front end. The syntax defined by
* API-A-LITE has for getting a description of the repository has the following
* binding:
* <ol>
* <li>getObjectHistory URL syntax:
* protocol://hostname:port/fedora/getObjectHistory/pid[?xml=BOOLEAN] This
* syntax requests information about the repository. The xml parameter
* determines the type of output returned. If the parameter is omitted or has a
* value of "false", a MIME-typed stream consisting of an html table is returned
* providing a browser-savvy means of viewing the object profile. If the value
* specified is "true", then a MIME-typed stream consisting of XML is returned.</li>
* <ul>
* <li>protocol - either http or https.</li>
* <li>hostname - required hostname of the Fedora server.</li>
* <li>port - required port number on which the Fedora server is running.</li>
* <li>fedora - required name of the Fedora access service.</li>
* <li>getObjectHistory - required verb of the Fedora service.</li>
* <li>pid - the persistent identifier of the digital object.
* <li>xml - an optional parameter indicating the requested output format. A
* value of "true" indicates a return type of text/xml; the absence of the xml
* parameter or a value of "false" indicates format is to be text/html.</li>
* </ul>
*
* @author Ross Wayland
* @version $Id$
*/
public class GetObjectHistoryServlet
extends HttpServlet
implements Constants {
/** Logger for this class. */
private static final Logger LOG =
Logger.getLogger(GetObjectHistoryServlet.class.getName());
private static final long serialVersionUID = 1L;
/** Content type for html. */
private static final String CONTENT_TYPE_HTML = "text/html; charset=UTF-8";
/** Content type for xml. */
private static final String CONTENT_TYPE_XML = "text/xml; charset=UTF-8";
/** Instance of the Fedora server. */
private static Server s_server = null;
/** Instance of the access subsystem. */
private static Access s_access = null;
public static final String ACTION_LABEL = "Get Object History";
/**
* <p>
* Process Fedora Access Request. Parse and validate the servlet input
* parameters and then execute the specified request.
* </p>
*
* @param request
* The servlet request.
* @param response
* servlet The servlet response.
* @throws ServletException
* If an error occurs that effects the servlet's basic operation.
* @throws IOException
* If an error occurrs with an input or output operation.
*/
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String PID = null;
boolean xml = false;
// Parse servlet URL.
String[] URIArray = request.getRequestURL().toString().split("/");
if (URIArray.length != 6 || !URIArray[4].equals("getObjectHistory")) {
throw new BadRequest400Exception(request,
ACTION_LABEL,
"",
new String[0]);
}
PID = URIArray[5];
LOG.debug("Servicing getObjectHistory request (PID=" + PID + ")");
// Check for xml encoding parameter; ignore any other parameters
Hashtable<String, String> h_userParms = new Hashtable<String, String>();
for (Enumeration<?> e = request.getParameterNames(); e.hasMoreElements();) {
String name = URLDecoder.decode((String) e.nextElement(), "UTF-8");
String value =
URLDecoder.decode(request.getParameter(name), "UTF-8");
if (name.equalsIgnoreCase("xml")) {
xml = new Boolean(request.getParameter(name)).booleanValue();
}
h_userParms.put(name, value);
}
Context context =
ReadOnlyContext.getContext(HTTP_REQUEST.REST.uri, request);
try {
getObjectHistory(context, PID, xml, response);
} catch (ObjectNotFoundException e) {
LOG.error("Object not found for request: "
+ request.getRequestURI() + " (actionLabel=" + ACTION_LABEL
+ ")", e);
throw new NotFound404Exception(request,
ACTION_LABEL,
"",
new String[0]);
} catch (ObjectNotInLowlevelStorageException e) {
LOG.error("Object not found for request: "
+ request.getRequestURI() + " (actionLabel=" + ACTION_LABEL
+ ")", e);
throw new NotFound404Exception(request,
ACTION_LABEL,
"",
new String[0]);
} catch (AuthzException ae) {
throw RootException.getServletException(ae,
request,
ACTION_LABEL,
new String[0]);
} catch (Throwable th) {
LOG.error("Unexpected error servicing API-A request", th);
throw new InternalError500Exception("",
th,
request,
ACTION_LABEL,
"",
new String[0]);
}
}
public void getObjectHistory(Context context,
String PID,
boolean xml,
HttpServletResponse response)
throws ServerException {
OutputStreamWriter out = null;
String[] objectHistory = new String[0];
PipedWriter pw = null;
PipedReader pr = null;
try {
pw = new PipedWriter();
pr = new PipedReader(pw);
objectHistory = s_access.getObjectHistory(context, PID);
if (objectHistory.length > 0) {
// Object history.
// Serialize the ObjectHistory object into XML
new ObjectHistorySerializerThread(context,
objectHistory,
PID,
pw).start();
if (xml) {
// Return results as raw XML
response.setContentType(CONTENT_TYPE_XML);
// Insures stream read from PipedReader correctly translates
// utf-8
// encoded characters to OutputStreamWriter.
out =
new OutputStreamWriter(response.getOutputStream(),
"UTF-8");
int bufSize = 4096;
char[] buf = new char[bufSize];
int len = 0;
while ((len = pr.read(buf, 0, bufSize)) != -1) {
out.write(buf, 0, len);
}
out.flush();
} else {
// Transform results into an html table
response.setContentType(CONTENT_TYPE_HTML);
out =
new OutputStreamWriter(response.getOutputStream(),
"UTF-8");
File xslFile =
new File(s_server.getHomeDir(),
"access/viewObjectHistory.xslt");
TransformerFactory factory =
XmlTransformUtility.getTransformerFactory();
Templates template =
factory.newTemplates(new StreamSource(xslFile));
Transformer transformer = template.newTransformer();
transformer.setParameter("fedora", context
.getEnvironmentValue(FEDORA_APP_CONTEXT_NAME));
transformer.transform(new StreamSource(pr),
new StreamResult(out));
}
out.flush();
} else {
throw new GeneralException("No object history returned");
}
} catch (ServerException e) {
throw e;
} catch (Throwable th) {
String msg = "Error getting object history";
throw new GeneralException(msg, th);
} finally {
try {
if (pr != null) {
pr.close();
}
if (out != null) {
out.close();
}
} catch (Throwable th) {
String message =
"[GetObjectHistoryServlet] An error has occured. "
+ " The error was a \" "
+ th.getClass().getName() + " \". Reason: "
+ th.getMessage();
throw new StreamIOException(message);
}
}
}
/**
* <p>
* A Thread to serialize an ObjectProfile object into XML.
* </p>
*/
public class ObjectHistorySerializerThread
extends Thread {
private PipedWriter pw = null;
private String[] objectHistory = new String[0];
private String PID = null;
/**
* <p>
* Constructor for ObjectHistorySerializerThread.
* </p>
*
* @param objectHistory
* An object history data structure.
* @param PID
* The pid of the digital object.
* @param pw
* A PipedWriter to which the serialization info is written.
*/
public ObjectHistorySerializerThread(Context context,
String[] objectHistory,
String PID,
PipedWriter pw) {
this.pw = pw;
this.objectHistory = objectHistory;
this.PID = PID;
if (HTTP_REQUEST.SECURE.uri.equals(context
.getEnvironmentValue(HTTP_REQUEST.SECURITY.uri))) {
} else if (HTTP_REQUEST.INSECURE.uri.equals(context
.getEnvironmentValue(HTTP_REQUEST.SECURITY.uri))) {
}
}
/**
* <p>
* This method executes the thread.
* </p>
*/
@Override
public void run() {
if (pw != null) {
try {
pw.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
pw.write("<fedoraObjectHistory" + " pid=\"" + PID + "\""
+ " xmlns:xsd=\"" + XML_XSD.uri + "\""
+ " xmlns:xsi=\"" + XSI.uri + "\""
+ " xsi:schemaLocation=\"" + ACCESS.uri + " "
+ OBJ_HISTORY1_0.xsdLocation + "\">");
// Object History Serialization
for (String element : objectHistory) {
pw.write("<objectChangeDate>" + element
+ "</objectChangeDate>");
}
pw.write("</fedoraObjectHistory>");
pw.flush();
pw.close();
} catch (IOException ioe) {
LOG.error("WriteThread error", ioe);
} finally {
try {
if (pw != null) {
pw.close();
}
} catch (IOException ioe) {
LOG.error("WriteThread error", ioe);
}
}
}
}
}
/**
* <p>
* For now, treat a HTTP POST request just like a GET request.
* </p>
*
* @param request
* The servet request.
* @param response
* The servlet response.
* @throws ServletException
* If thrown by <code>doGet</code>.
* @throws IOException
* If thrown by <code>doGet</code>.
*/
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* <p>
* Initialize servlet.
* </p>
*
* @throws ServletException
* If the servet cannot be initialized.
*/
@Override
public void init() throws ServletException {
try {
s_server = Server.getInstance(new File(FEDORA_HOME), false);
s_access =
(Access) s_server.getModule("fedora.server.access.Access");
} catch (InitializationException ie) {
throw new ServletException("Unable to get Fedora Server instance."
+ ie.getMessage());
}
}
}