/*
* FeedServlet.java
*
* Version: $Revision: 4511 $
*
* Date: $Date: 2009-11-06 04:26:26 +0000 (Fri, 06 Nov 2009) $
*
* Copyright (c) 2002-2005, Hewlett-Packard Company and Massachusetts
* Institute of Technology. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the Hewlett-Packard Company nor the name of the
* Massachusetts Institute of Technology nor the names of their
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
package org.dspace.app.webui.servlet;
import java.io.IOException;
import java.sql.SQLException;
import java.text.MessageFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;
import java.util.StringTokenizer;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.dspace.app.util.SyndicationFeed;
import org.dspace.app.webui.util.JSPManager;
import org.dspace.authorize.AuthorizeException;
import org.dspace.authorize.AuthorizeManager;
import org.dspace.browse.BrowseEngine;
import org.dspace.browse.BrowseException;
import org.dspace.browse.BrowseIndex;
import org.dspace.browse.BrowseInfo;
import org.dspace.browse.BrowserScope;
import org.dspace.sort.SortOption;
import org.dspace.sort.SortException;
import org.dspace.content.Bitstream;
import org.dspace.content.Collection;
import org.dspace.content.Community;
import org.dspace.content.DCDate;
import org.dspace.content.DCValue;
import org.dspace.content.DSpaceObject;
import org.dspace.content.Item;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.Constants;
import org.dspace.core.Context;
import org.dspace.core.LogManager;
import org.dspace.handle.HandleManager;
import org.dspace.search.Harvest;
import org.dspace.eperson.Group;
import com.sun.syndication.feed.rss.Channel;
import com.sun.syndication.feed.rss.Description;
import com.sun.syndication.feed.rss.Image;
import com.sun.syndication.feed.rss.TextInput;
import com.sun.syndication.io.FeedException;
import com.sun.syndication.io.WireFeedOutput;
/**
* Servlet for handling requests for a syndication feed. The Handle of the collection
* or community is extracted from the URL, e.g: <code>/feed/rss_1.0/1234/5678</code>.
* Currently supports only RSS feed formats.
*
* @author Ben Bosman, Richard Rodgers
* @version $Revision: 4511 $
*/
public class FeedServlet extends DSpaceServlet
{
// key for site-wide feed
public static final String SITE_FEED_KEY = "site";
// one hour in milliseconds
private static final long HOUR_MSECS = 60 * 60 * 1000;
/** log4j category */
private static Logger log = Logger.getLogger(FeedServlet.class);
private String clazz = "org.dspace.app.webui.servlet.FeedServlet";
// are syndication feeds enabled?
private static boolean enabled = false;
// number of DSpace items per feed
private static int itemCount = 0;
// optional cache of feeds
private static Map feedCache = null;
// maximum size of cache - 0 means caching disabled
private static int cacheSize = 0;
// how many days to keep a feed in cache before checking currency
private static int cacheAge = 0;
// supported syndication formats
private static List formats = null;
// Whether to include private items or not
private static boolean includeAll = true;
//default fields to display in item description
private static String defaultDescriptionFields = "dc.title, dc.contributor.author, dc.contributor.editor, dc.description.abstract, dc.description";
static
{
enabled = ConfigurationManager.getBooleanProperty("webui.feed.enable");
}
public void init()
{
// read rest of config info if enabled
if (enabled)
{
String fmtsStr = ConfigurationManager.getProperty("webui.feed.formats");
if ( fmtsStr != null )
{
formats = new ArrayList();
String[] fmts = fmtsStr.split(",");
for (int i = 0; i < fmts.length; i++)
{
formats.add(fmts[i]);
}
}
itemCount = ConfigurationManager.getIntProperty("webui.feed.items");
cacheSize = ConfigurationManager.getIntProperty("webui.feed.cache.size");
if (cacheSize > 0)
{
feedCache = new HashMap();
cacheAge = ConfigurationManager.getIntProperty("webui.feed.cache.age");
}
}
}
protected void doDSGet(Context context, HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException,
SQLException, AuthorizeException
{
includeAll = ConfigurationManager.getBooleanProperty("harvest.includerestricted.rss", true);
String path = request.getPathInfo();
String feedType = null;
String handle = null;
// build label map from localized Messages resource bundle
Locale locale = request.getLocale();
ResourceBundle msgs = ResourceBundle.getBundle("Messages", locale);
Map<String, String> labelMap = new HashMap<String, String>();
labelMap.put(SyndicationFeed.MSG_UNTITLED, msgs.getString(clazz + ".notitle"));
labelMap.put(SyndicationFeed.MSG_LOGO_TITLE, msgs.getString(clazz + ".logo.title"));
labelMap.put(SyndicationFeed.MSG_FEED_DESCRIPTION, msgs.getString(clazz + ".general-feed.description"));
labelMap.put(SyndicationFeed.MSG_UITYPE, SyndicationFeed.UITYPE_JSPUI);
for (String selector : SyndicationFeed.getDescriptionSelectors())
{
labelMap.put("metadata." + selector, msgs.getString(SyndicationFeed.MSG_METADATA + selector));
}
if (path != null)
{
// substring(1) is to remove initial '/'
path = path.substring(1);
int split = path.indexOf("/");
if (split != -1)
{
feedType = path.substring(0,split);
handle = path.substring(split+1);
}
}
DSpaceObject dso = null;
//as long as this is not a site wide feed,
//attempt to retrieve the Collection or Community object
if(handle != null && !handle.equals(SITE_FEED_KEY))
{
// Determine if handle is a valid reference
dso = HandleManager.resolveToObject(context, handle);
if (dso == null)
{
log.info(LogManager.getHeader(context, "invalid_handle", "path=" + path));
JSPManager.showInvalidIDError(request, response, handle, -1);
return;
}
}
if (! enabled || (dso != null &&
(dso.getType() != Constants.COLLECTION && dso.getType() != Constants.COMMUNITY)) )
{
log.info(LogManager.getHeader(context, "invalid_id", "path=" + path));
JSPManager.showInvalidIDError(request, response, path, -1);
return;
}
// Determine if requested format is supported
if( feedType == null || ! formats.contains( feedType ) )
{
log.info(LogManager.getHeader(context, "invalid_syndformat", "path=" + path));
JSPManager.showInvalidIDError(request, response, path, -1);
return;
}
if (dso != null && dso.getType() == Constants.COLLECTION)
{
labelMap.put(SyndicationFeed.MSG_FEED_TITLE,
MessageFormat.format(msgs.getString(clazz + ".feed.title"),
new Object[]{ msgs.getString(clazz + ".feed-type.collection"),
((Collection)dso).getMetadata("short_description")}));
}
else if (dso != null && dso.getType() == Constants.COMMUNITY)
{
labelMap.put(SyndicationFeed.MSG_FEED_TITLE,
MessageFormat.format(msgs.getString(clazz + ".feed.title"),
new Object[]{ msgs.getString(clazz + ".feed-type.community"),
((Community)dso).getMetadata("short_description")}));
}
// Lookup or generate the feed
// Cache key is handle + locale
String cacheKey = (handle==null?"site":handle)+"."+locale.toString();
SyndicationFeed feed = null;
if (feedCache != null)
{
CacheFeed cFeed = (CacheFeed)feedCache.get(cacheKey);
if (cFeed != null) // cache hit, but...
{
// Is the feed current?
boolean cacheFeedCurrent = false;
if (cFeed.timeStamp + (cacheAge * HOUR_MSECS) < System.currentTimeMillis())
{
cacheFeedCurrent = true;
}
// Not current, but have any items changed since feed was created/last checked?
else if ( ! itemsChanged(context, dso, cFeed.timeStamp))
{
// no items have changed, re-stamp feed and use it
cFeed.timeStamp = System.currentTimeMillis();
cacheFeedCurrent = true;
}
if (cacheFeedCurrent)
{
feed = cFeed.access();
}
}
}
// either not caching, not found in cache, or feed in cache not current
if (feed == null)
{
feed = new SyndicationFeed(SyndicationFeed.UITYPE_JSPUI);
feed.populate(request, dso, getItems(context, dso), labelMap);
if (feedCache != null)
{
cache(cacheKey, new CacheFeed(feed));
}
}
// set the feed to the requested type & return it
try
{
feed.setType(feedType);
response.setContentType("text/xml; charset=UTF-8");
feed.output(response.getWriter());
}
catch( FeedException fex )
{
throw new IOException(fex.getMessage());
}
}
private boolean itemsChanged(Context context, DSpaceObject dso, long timeStamp)
throws SQLException
{
// construct start and end dates
DCDate dcStartDate = new DCDate( new Date(timeStamp) );
DCDate dcEndDate = new DCDate( new Date(System.currentTimeMillis()) );
// convert dates to ISO 8601, stripping the time
String startDate = dcStartDate.toString().substring(0, 10);
String endDate = dcEndDate.toString().substring(0, 10);
// this invocation should return a non-empty list if even 1 item has changed
try {
return (Harvest.harvest(context, dso, startDate, endDate,
0, 1, !includeAll, false, false, includeAll).size() > 0);
}
catch (ParseException pe)
{
// This should never get thrown as we have generated the dates ourselves
return false;
}
}
// returns recently changed items, checking for accessibility
private Item[] getItems(Context context, DSpaceObject dso)
throws IOException, SQLException
{
try
{
// new method of doing the browse:
String idx = ConfigurationManager.getProperty("recent.submissions.sort-option");
if (idx == null)
{
throw new IOException("There is no configuration supplied for: recent.submissions.sort-option");
}
BrowseIndex bix = BrowseIndex.getItemBrowseIndex();
if (bix == null)
{
throw new IOException("There is no browse index with the name: " + idx);
}
BrowserScope scope = new BrowserScope(context);
scope.setBrowseIndex(bix);
if (dso != null)
scope.setBrowseContainer(dso);
for (SortOption so : SortOption.getSortOptions())
{
if (so.getName().equals(idx))
scope.setSortBy(so.getNumber());
}
scope.setOrder(SortOption.DESCENDING);
scope.setResultsPerPage(itemCount);
// gather & add items to the feed.
BrowseEngine be = new BrowseEngine(context);
BrowseInfo bi = be.browseMini(scope);
Item[] results = bi.getItemResults(context);
if (includeAll)
{
return results;
}
else
{
// Check to see if we can include this item
//Group[] authorizedGroups = AuthorizeManager.getAuthorizedGroups(context, results[i], Constants.READ);
//boolean added = false;
List<Item> items = new ArrayList<Item>();
for (Item result : results)
{
checkAccess:
for (Group group : AuthorizeManager.getAuthorizedGroups(context, result, Constants.READ))
{
if ((group.getID() == 0))
{
items.add(result);
break checkAccess;
}
}
}
return items.toArray(new Item[items.size()]);
}
}
catch (SortException se)
{
log.error("caught exception: ", se);
throw new IOException(se.getMessage());
}
catch (BrowseException e)
{
log.error("caught exception: ", e);
throw new IOException(e.getMessage());
}
}
/************************************************
* private cache management classes and methods *
************************************************/
/**
* Add a feed to the cache - reducing the size of the cache by 1 to make room if
* necessary. The removed entry has an access count equal to the minumum in the cache.
* @param feedKey
* The cache key for the feed
* @param newFeed
* The CacheFeed feed to be cached
*/
private static void cache(String feedKey, CacheFeed newFeed)
{
// remove older feed to make room if cache full
if (feedCache.size() >= cacheSize)
{
// cache profiling data
int total = 0;
String minKey = null;
CacheFeed minFeed = null;
CacheFeed maxFeed = null;
Iterator iter = feedCache.keySet().iterator();
while (iter.hasNext())
{
String key = (String)iter.next();
CacheFeed feed = (CacheFeed)feedCache.get(key);
if (minKey != null)
{
if (feed.hits < minFeed.hits)
{
minKey = key;
minFeed = feed;
}
if (feed.hits >= maxFeed.hits)
{
maxFeed = feed;
}
}
else
{
minKey = key;
minFeed = maxFeed = feed;
}
total += feed.hits;
}
// log a profile of the cache to assist administrator in tuning it
int avg = total / feedCache.size();
String logMsg = "feedCache() - size: " + feedCache.size() +
" Hits - total: " + total + " avg: " + avg +
" max: " + maxFeed.hits + " min: " + minFeed.hits;
log.info(logMsg);
// remove minimum hits entry
feedCache.remove(minKey);
}
// add feed to cache
feedCache.put(feedKey, newFeed);
}
/**
* Class to instrument accesses & currency of a given feed in cache
*/
private class CacheFeed
{
// currency timestamp
public long timeStamp = 0L;
// access count
public int hits = 0;
// the feed
private SyndicationFeed feed = null;
public CacheFeed(SyndicationFeed feed)
{
this.feed = feed;
timeStamp = System.currentTimeMillis();
}
public SyndicationFeed access()
{
++hits;
return feed;
}
}
}