/projects/rssowl-2.0.5/org.rssowl.ui/src/org/rssowl/ui/internal/ApplicationServer.java

/*   **********************************************************************  **

 **   Copyright notice                                                       **

 **                                                                          **

 **   (c) 2005-2009 RSSOwl Development Team                                  **

 **   http://www.rssowl.org/                                                 **

 **                                                                          **

 **   All rights reserved                                                    **

 **                                                                          **

 **   This program and the accompanying materials are made available under   **

 **   the terms of the Eclipse Public License v1.0 which accompanies this    **

 **   distribution, and is available at:                                     **

 **   http://www.rssowl.org/legal/epl-v10.html                               **

 **                                                                          **

 **   A copy is found in the file epl-v10.html and important notices to the  **

 **   license from the team is found in the textfile LICENSE.txt distributed **

 **   in this package.                                                       **

 **                                                                          **

 **   This copyright notice MUST APPEAR in all copies of the file!           **

 **                                                                          **

 **   Contributors:                                                          **

 **     RSSOwl Development Team - initial API and implementation             **

 **                                                                          **

 **  **********************************************************************  */



package org.rssowl.ui.internal;



import org.eclipse.core.runtime.IProgressMonitor;

import org.eclipse.core.runtime.IStatus;

import org.eclipse.core.runtime.SafeRunner;

import org.eclipse.core.runtime.Status;

import org.eclipse.core.runtime.jobs.Job;

import org.eclipse.jface.viewers.ContentViewer;

import org.eclipse.jface.viewers.IStructuredContentProvider;

import org.rssowl.core.persist.IBookMark;

import org.rssowl.core.persist.IEntity;

import org.rssowl.core.persist.INews;

import org.rssowl.core.persist.INewsBin;

import org.rssowl.core.persist.ISearchMark;

import org.rssowl.core.persist.reference.BookMarkReference;

import org.rssowl.core.persist.reference.FolderReference;

import org.rssowl.core.persist.reference.ModelReference;

import org.rssowl.core.persist.reference.NewsBinReference;

import org.rssowl.core.persist.reference.NewsReference;

import org.rssowl.core.persist.reference.SearchMarkReference;

import org.rssowl.core.util.CoreUtils;

import org.rssowl.core.util.LoggingSafeRunnable;

import org.rssowl.core.util.StringUtils;

import org.rssowl.core.util.URIUtils;

import org.rssowl.ui.internal.FolderNewsMark.FolderNewsMarkReference;

import org.rssowl.ui.internal.editors.feed.NewsBrowserLabelProvider;

import org.rssowl.ui.internal.editors.feed.NewsBrowserViewer;



import java.io.BufferedOutputStream;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.net.BindException;

import java.net.InetAddress;

import java.net.ServerSocket;

import java.net.Socket;

import java.net.UnknownHostException;

import java.text.DateFormat;

import java.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Date;

import java.util.List;

import java.util.Locale;

import java.util.Map;

import java.util.StringTokenizer;

import java.util.concurrent.ConcurrentHashMap;



/**

 * The <code>NewsServer</code> is a Singleton that serves HTML for a request of

 * News. A Browser can navigate to a local URL with Port 8795 and use some

 * special parameters to request either a List of News or complete Feeds.

 * <p>

 * TODO As more and more stuff is handled by this server, it should be

 * considered to make it extensible by allowing to register handlers for certain

 * operations.

 * </p>

 *

 * @author bpasero

 */

public class ApplicationServer {



  /* The Singleton Instance */

  private static ApplicationServer fgInstance = new ApplicationServer();



  /* Local URL Default Values */

  static final String PROTOCOL = "http"; //$NON-NLS-1$

  static final String DEFAULT_LOCALHOST = "127.0.0.1"; //$NON-NLS-1$

  @SuppressWarnings("all")

  static final int DEFAULT_SOCKET_PORT = Application.IS_ECLIPSE ? 8775 : 8795;



  /* Local URL Parts */

  static String LOCALHOST = DEFAULT_LOCALHOST;

  static int SOCKET_PORT = DEFAULT_SOCKET_PORT;



  /* Handshake Message */

  static final String STARTUP_HANDSHAKE = "org.rssowl.ui.internal.StartupHandshake"; //$NON-NLS-1$



  /* DWord controlling the startup-handshake */

  private static final String MULTI_INSTANCE_PROPERTY = "multiInstance"; //$NON-NLS-1$



  /* DWord controlling the localhost value */

  private static final String LOCALHOST_PROPERTY = "localhost"; //$NON-NLS-1$



  /* DWord controlling the port value */

  private static final String PORT_PROPERTY = "port"; //$NON-NLS-1$



  /* Identifies the Viewer providing the Content */

  private static final String ID = "id="; //$NON-NLS-1$



  /* Used after all HTTP-Headers */

  private static final String CRLF = "\r\n"; //$NON-NLS-1$



  /* Registry of known Viewer */

  private static Map<String, ContentViewer> fRegistry = new ConcurrentHashMap<String, ContentViewer>();



  /* Supported Operations */

  private static final String OP_DISPLAY_FOLDER = "displayFolder="; //$NON-NLS-1$

  private static final String OP_DISPLAY_BOOKMARK = "displayBookMark="; //$NON-NLS-1$

  private static final String OP_DISPLAY_NEWSBIN = "displayNewsBin="; //$NON-NLS-1$

  private static final String OP_DISPLAY_SEARCHMARK = "displaySearchMark="; //$NON-NLS-1$

  private static final String OP_DISPLAY_NEWS = "displayNews="; //$NON-NLS-1$

  private static final String OP_RESOURCE = "resource="; //$NON-NLS-1$



  /* Windows only: Mark of the Web */

  private static final String IE_MOTW = "<!-- saved from url=(0014)about:internet -->"; //$NON-NLS-1$



  /* RFC 1123 Date Format for the respond header */

  private static final DateFormat RFC_1123_DATE = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.ENGLISH); //$NON-NLS-1$



  /* Interface used to handle a startup-handshake */

  static interface HandshakeHandler {



    /**

     * Handler for the hand-shake done on startup in case the application server

     * was found already running by another RSSOwl process.

     *

     * @param token A message to pass via hand-shake.

     */

    void handle(String token);

  }



  private ServerSocket fSocket;

  private Job fServerJob;

  private int fPort;

  private HandshakeHandler fHandshakeHandler;



  /**

   * Returns the singleton instance of the ApplicationServer.

   *

   * @return the singleton instance of the ApplicationServer.

   */

  public static ApplicationServer getDefault() {

    return fgInstance;

  }



  /**

   * Attempts to start the server. Will throw an IOException in case of a

   * problem.

   *

   * @throws IOException in case of a problem starting the server.

   * @throws UnknownHostException in case the host is unknown.

   * @throws BindException in case of a failure binding the server to a port.

   */

  public void startup() throws IOException {



    /* Server already running */

    if (isRunning())

      return;



    /* Determine Localhost Value */

    String localhostProperty = System.getProperty(LOCALHOST_PROPERTY);

    if (localhostProperty != null && localhostProperty.length() > 0)

      LOCALHOST = localhostProperty;



    /* Determine Port Value */

    String portProperty = System.getProperty(PORT_PROPERTY);

    if (portProperty != null && portProperty.length() > 0) {

      try {

        SOCKET_PORT = Integer.parseInt(portProperty);

      } catch (NumberFormatException e) {

        Activator.getDefault().logError(e.getMessage(), e);

      }

    }



    /* Server not yet running */

    boolean usePortRange = Application.IS_ECLIPSE || System.getProperty(MULTI_INSTANCE_PROPERTY) != null;

    fSocket = createServerSocket(usePortRange);

    if (fSocket != null)

      listen();

  }



  /** Stop the Application Server */

  public void shutdown() {

    fServerJob.cancel();

    try {

      if (fSocket != null)

        fSocket.close();

    } catch (IOException e) {

      if (Activator.getDefault() != null)

        Activator.getDefault().logError(e.getMessage(), e);

    }

  }



  /**

   * Check if the server is running or not.

   *

   * @return <code>TRUE</code> in case the server is running and

   * <code>FALSE</code> otherwise.

   */

  public boolean isRunning() {

    return fSocket != null;

  }



  /* Registers the Handler for Hand-Shaking on startup */

  void setHandshakeHandler(HandshakeHandler handler) {

    fHandshakeHandler = handler;

  }



  /* Attempt to create Server-Socket with retry-option */

  private ServerSocket createServerSocket(boolean usePortRange) throws IOException {



    /* Ports to try */

    List<Integer> ports = new ArrayList<Integer>();

    ports.add(SOCKET_PORT);



    /* Try up to 10 different ports if set */

    if (usePortRange) {

      for (int i = 1; i < 10; i++)

        ports.add(SOCKET_PORT + i);

    }



    /* Attempt to open Port */

    for (int i = 0; i < ports.size(); i++) {

      try {

        int port = ports.get(i);

        fPort = port;

        return new ServerSocket(fPort, 50, InetAddress.getByName(LOCALHOST));

      } catch (UnknownHostException e) {

        throw e;

      } catch (BindException e) {

        if (i == (ports.size() - 1))

          throw e;

      }

    }



    return null;

  }



  /**

   * Returns <code>TRUE</code> if the given URL is a local NewsServer URL.

   *

   * @param url The URL to check for being a NewsServer URL.

   * @return <code>TRUE</code> if the given URL is a local NewsServer URL.

   */

  public boolean isNewsServerUrl(String url) {

    return url.contains(LOCALHOST) && url.contains(String.valueOf(fPort));

  }



  /**

   * Registers a Viewer under a certain ID to the Registry. Viewers need to

   * register if they want to use the Server. Based on the ID, the Server is

   * asking the correct Viewer for the Content.

   *

   * @param id The unique ID under which the Viewer is stored in the registry.

   * @param viewer The Viewer to store in the registry.

   */

  public void register(String id, ContentViewer viewer) {

    fRegistry.put(id, viewer);

  }



  /**

   * Removes a Viewer from the registry.

   *

   * @param id The ID of the Viewer to remove from the registry.

   */

  public void unregister(String id) {

    fRegistry.remove(id);

  }



  /**

   * Check wether the given URL contains one of the display-operations of this

   * Server.

   *

   * @param url The URL to Test for a Display Operation.

   * @return Returns <code>TRUE</code> if the given URL is a display-operation.

   */

  public boolean isDisplayOperation(String url) {

    if (!StringUtils.isSet(url))

      return false;



    return url.contains(OP_DISPLAY_FOLDER) || url.contains(OP_DISPLAY_BOOKMARK) || url.contains(OP_DISPLAY_NEWSBIN) || url.contains(OP_DISPLAY_NEWS) || url.contains(OP_DISPLAY_SEARCHMARK) || URIUtils.ABOUT_BLANK.equals(url);

  }



  /**

   * Check wether the given URL contains one of the resource-operations of this

   * Server.

   *

   * @param url The URL to Test for a Resource Operation.

   * @return Returns <code>TRUE</code> if the given URL is a resource-operation.

   */

  public boolean isResourceOperation(String url) {

    if (!StringUtils.isSet(url))

      return false;



    return url.contains(OP_RESOURCE);

  }



  /**

   * @param path the path to the resource in the plugin.

   * @return a url that can be used to access the resource.

   */

  public String toResourceUrl(String path) {

    StringBuilder url = new StringBuilder();

    url.append(PROTOCOL).append("://").append(LOCALHOST).append(':').append(fPort).append("/"); //$NON-NLS-1$ //$NON-NLS-2$

    url.append("?").append(OP_RESOURCE).append(path); //$NON-NLS-1$



    return url.toString();

  }



  /**

   * Creates a valid URL for the given Input

   *

   * @param id The ID of the Viewer

   * @param input The Input of the Viewer

   * @return a valid URL for the given Input

   */

  public String toUrl(String id, Object input) {



    /* Handle this Case */

    if (input == null)

      return URIUtils.ABOUT_BLANK;



    StringBuilder url = new StringBuilder();

    url.append(PROTOCOL).append("://").append(LOCALHOST).append(':').append(fPort).append("/"); //$NON-NLS-1$ //$NON-NLS-2$



    /* Append the ID */

    url.append("?").append(ID).append(id); //$NON-NLS-1$



    /* Wrap into Object Array */

    if (!(input instanceof Object[]))

      input = new Object[] { input };



    /* Input is an Array of Objects */

    List<Long> news = new ArrayList<Long>();

    List<Long> bookmarks = new ArrayList<Long>();

    List<Long> newsbins = new ArrayList<Long>();

    List<Long> searchmarks = new ArrayList<Long>();

    List<Long> folders = new ArrayList<Long>();



    /* Split into BookMarks, NewsBins, SearchMarks and News */

    for (Object obj : (Object[]) input) {

      if (obj instanceof FolderNewsMarkReference)

        folders.add(getId(obj));

      else if (obj instanceof IBookMark || obj instanceof BookMarkReference)

        bookmarks.add(getId(obj));

      else if (obj instanceof INewsBin || obj instanceof NewsBinReference)

        newsbins.add(getId(obj));

      else if (obj instanceof ISearchMark || obj instanceof SearchMarkReference)

        searchmarks.add(getId(obj));

      else if (obj instanceof INews || obj instanceof NewsReference)

        news.add(getId(obj));

      else if (obj instanceof EntityGroup) {

        List<EntityGroupItem> items = ((EntityGroup) obj).getItems();

        for (EntityGroupItem item : items) {

          IEntity entity = item.getEntity();

          if (entity instanceof INews)

            news.add(getId(entity));

        }

      }

    }



    /* Append Parameter for Folders */

    appendParameters(url, folders, OP_DISPLAY_FOLDER);



    /* Append Parameter for Bookmarks */

    appendParameters(url, bookmarks, OP_DISPLAY_BOOKMARK);



    /* Append Parameter for Newsbins */

    appendParameters(url, newsbins, OP_DISPLAY_NEWSBIN);



    /* Append Parameter for SearchMarks */

    appendParameters(url, searchmarks, OP_DISPLAY_SEARCHMARK);



    /* Append Parameter for News */

    appendParameters(url, news, OP_DISPLAY_NEWS);



    return url.toString();

  }



  private void appendParameters(StringBuilder url, List<Long> ids, String op) {

    if (!ids.isEmpty()) {

      url.append("&").append(op); //$NON-NLS-1$

      for (Long id : ids)

        url.append(id).append(',');



      /* Remove the last added ',' */

      url.deleteCharAt(url.length() - 1);

    }

  }



  private Long getId(Object obj) {

    if (obj instanceof IEntity)

      return ((IEntity) obj).getId();

    else if (obj instanceof ModelReference)

      return ((ModelReference) obj).getId();



    return null;

  }



  private void listen() {



    /* Create a Job to listen for Requests */

    fServerJob = new Job("Local News Viewer Server") { //$NON-NLS-1$

      @Override

      protected IStatus run(IProgressMonitor monitor) {



        /* Listen as long not canceled */

        while (!monitor.isCanceled()) {

          BufferedReader buffReader = null;

          Socket socket = null;

          try {



            /* Blocks until Socket accepted */

            socket = fSocket.accept();



            /* Read Incoming Message */

            buffReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            String message = buffReader.readLine();



            /* Process Message */

            if (StringUtils.isSet(message))

              safeProcess(socket, message);

          } catch (IOException e) {

            /* Ignore */

          }



          /* Cleanup */

          finally {



            /* Close the Reader */

            try {

              if (buffReader != null)

                buffReader.close();

            } catch (Exception e) {

              /* Ignore */

            }



            /* Close the Socket */

            try {

              if (socket != null)

                socket.close();

            } catch (Exception e) {

              /* Ignore */

            }

          }

        }

        return Status.OK_STATUS;

      }

    };



    /* Set as System-Job and Schedule */

    fServerJob.setSystem(true);

    fServerJob.schedule();

  }



  /* Process Message in Safe-Runnable */

  private void safeProcess(final Socket socket, final String message) {

    SafeRunner.run(new LoggingSafeRunnable() {

      public void run() throws Exception {



        /* This is a Display-Operation */

        if (isDisplayOperation(message))

          processDisplayOperation(socket, message);



        /* This is a Resource-Operation */

        else if (isResourceOperation(message))

          processResourceOperation(socket, message);



        /* This is a startup handshake */

        else

          processHandshake(message);

      }

    });

  }



  /* Process Handshake-Message */

  private void processHandshake(String message) {

    if (fHandshakeHandler != null)

      fHandshakeHandler.handle(message);

  }



  private void processResourceOperation(Socket socket, String message) {



    /* Substring to get the Parameters String */

    int start = message.indexOf(OP_RESOURCE) + OP_RESOURCE.length();

    int end = message.indexOf(' ', start);

    String parameter = message.substring(start, end);



    /* Write HTML to the Receiver */

    BufferedOutputStream outS = null;

    try {

      outS = new BufferedOutputStream(socket.getOutputStream());

      CoreUtils.copy(OwlUI.class.getResourceAsStream(parameter), outS);

    } catch (IOException e) {

      /* Ignore */

    }



    /* Cleanup */

    finally {

      if (outS != null) {

        try {

          outS.close();

        } catch (IOException e) {

          /* Ignore */

        }

      }

    }

  }



  /* Process Message by looking for operations */

  private void processDisplayOperation(Socket socket, String message) {

    List<Object> elements = new ArrayList<Object>();



    /* Substring to get the Parameters String */

    int start = message.indexOf('/');

    int end = message.indexOf(' ', start);

    String parameters = message.substring(start, end);



    /* Retrieve the ID */

    String viewerId = null;

    int idIndex = parameters.indexOf(ID);

    if (idIndex >= 0) {

      start = idIndex + ID.length();

      end = parameters.indexOf('&', start);

      if (end < 0)

        end = parameters.length();



      viewerId = parameters.substring(start, end);

    }



    /* Ask for ContentProvider of Viewer */

    ContentViewer viewer = fRegistry.get(viewerId);

    if (viewer instanceof NewsBrowserViewer && viewer.getContentProvider() != null) {

      IStructuredContentProvider newsContentProvider = (IStructuredContentProvider) viewer.getContentProvider();



      /* Look for Folders that are to displayed */

      int displayFolderIndex = parameters.indexOf(OP_DISPLAY_FOLDER);

      if (displayFolderIndex >= 0) {

        start = displayFolderIndex + OP_DISPLAY_FOLDER.length();

        end = parameters.indexOf('&', start);

        if (end < 0)

          end = parameters.length();



        StringTokenizer tokenizer = new StringTokenizer(parameters.substring(start, end), ",");//$NON-NLS-1$

        while (tokenizer.hasMoreElements()) {

          FolderReference ref = new FolderReference(Long.valueOf((String) tokenizer.nextElement()));

          elements.addAll(Arrays.asList(newsContentProvider.getElements(ref)));

        }

      }



      /* Look for BookMarks that are to displayed */

      int displayBookMarkIndex = parameters.indexOf(OP_DISPLAY_BOOKMARK);

      if (displayBookMarkIndex >= 0) {

        start = displayBookMarkIndex + OP_DISPLAY_BOOKMARK.length();

        end = parameters.indexOf('&', start);

        if (end < 0)

          end = parameters.length();



        StringTokenizer tokenizer = new StringTokenizer(parameters.substring(start, end), ",");//$NON-NLS-1$

        while (tokenizer.hasMoreElements()) {

          BookMarkReference ref = new BookMarkReference(Long.valueOf((String) tokenizer.nextElement()));

          elements.addAll(Arrays.asList(newsContentProvider.getElements(ref)));

        }

      }



      /* Look for NewsBins that are to displayed */

      int displayNewsBinsIndex = parameters.indexOf(OP_DISPLAY_NEWSBIN);

      if (displayNewsBinsIndex >= 0) {

        start = displayNewsBinsIndex + OP_DISPLAY_NEWSBIN.length();

        end = parameters.indexOf('&', start);

        if (end < 0)

          end = parameters.length();



        StringTokenizer tokenizer = new StringTokenizer(parameters.substring(start, end), ",");//$NON-NLS-1$

        while (tokenizer.hasMoreElements()) {

          NewsBinReference ref = new NewsBinReference(Long.valueOf((String) tokenizer.nextElement()));

          elements.addAll(Arrays.asList(newsContentProvider.getElements(ref)));

        }

      }



      /* Look for SearchMarks that are to displayed */

      int displaySearchMarkIndex = parameters.indexOf(OP_DISPLAY_SEARCHMARK);

      if (displaySearchMarkIndex >= 0) {

        start = displaySearchMarkIndex + OP_DISPLAY_SEARCHMARK.length();

        end = parameters.indexOf('&', start);

        if (end < 0)

          end = parameters.length();



        StringTokenizer tokenizer = new StringTokenizer(parameters.substring(start, end), ",");//$NON-NLS-1$

        while (tokenizer.hasMoreElements()) {

          SearchMarkReference ref = new SearchMarkReference(Long.valueOf((String) tokenizer.nextElement()));

          elements.addAll(Arrays.asList(newsContentProvider.getElements(ref)));

        }

      }



      /* Look for News that are to displayed */

      int displayNewsIndex = parameters.indexOf(OP_DISPLAY_NEWS);

      if (displayNewsIndex >= 0) {

        start = displayNewsIndex + OP_DISPLAY_NEWS.length();

        end = parameters.indexOf('&', start);

        if (end < 0)

          end = parameters.length();



        StringTokenizer tokenizer = new StringTokenizer(parameters.substring(start, end), ",");//$NON-NLS-1$

        while (tokenizer.hasMoreElements()) {

          NewsReference ref = new NewsReference(Long.valueOf((String) tokenizer.nextElement()));

          elements.addAll(Arrays.asList(newsContentProvider.getElements(ref)));

        }

      }

    }



    /* Reply to the Socket */

    reply(socket, viewerId, elements.toArray());

  }



  /* Create HTML out of the Elements and reply to the Socket */

  private void reply(Socket socket, String viewerId, Object[] elements) {



    /* Only responsible for Viewer-Concerns */

    if (viewerId == null)

      return;



    /* Retrieve Viewer */

    ContentViewer viewer = fRegistry.get(viewerId);



    /* Might be bad timing */

    if (viewer == null)

      return;



    /* Ask for sorted Elements */

    NewsBrowserLabelProvider labelProvider = (NewsBrowserLabelProvider) viewer.getLabelProvider();

    Object[] children = new Object[0];

    if (viewer instanceof NewsBrowserViewer)

      children = ((NewsBrowserViewer) viewer).getFlattendChildren(elements);



    /* Write HTML to the Receiver */

    BufferedWriter writer = null;

    try {

      boolean portable = Controller.getDefault().isPortable();

      writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));



      if (Application.IS_WINDOWS && portable)

        writer.append("HTTP/1.1 205 OK").append(CRLF); //$NON-NLS-1$

      else

        writer.append("HTTP/1.1 200 OK").append(CRLF); //$NON-NLS-1$



      synchronized (RFC_1123_DATE) {

        writer.append("Date: ").append(RFC_1123_DATE.format(new Date())).append(CRLF); //$NON-NLS-1$

      }



      writer.append("Server: RSSOwl Local Server").append(CRLF); //$NON-NLS-1$

      writer.append("Content-Type: text/html; charset=UTF-8").append(CRLF); //$NON-NLS-1$

      writer.append("Connection: close").append(CRLF); //$NON-NLS-1$

      writer.append("Expires: 0").append(CRLF); //$NON-NLS-1$

      writer.write(CRLF);



      /* Begin HTML */

      writer.write("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">\n"); //$NON-NLS-1$



      /* Windows only: Mark of the Web */

      if (Application.IS_WINDOWS) {

        writer.write(IE_MOTW);

        writer.write("\n"); //$NON-NLS-1$

      }



      writer.write("<html>\n  <head>\n"); //$NON-NLS-1$



      /* Append Base URI if available */

      String base = getBase(children);

      if (base != null) {

        writer.write("  <base href=\""); //$NON-NLS-1$

        writer.write(base);

        writer.write("\">"); //$NON-NLS-1$

      }



      writer.write("\n  <title></title>"); //$NON-NLS-1$

      writer.write("\n  <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\n"); //$NON-NLS-1$



      /* CSS */

      labelProvider.writeCSS(writer);



      /* Open Body */

      writer.write("  </head>\n  <body id=\"owlbody\">\n"); //$NON-NLS-1$



      /* Output each Element as HTML */

      for (int i = 0; i < children.length; i++) {

        String html = unicodeToEntities(labelProvider.getText(children[i], i));

        writer.write(html);

      }



      /* End HTML */

      writer.write("\n  </body>\n</html>"); //$NON-NLS-1$

    } catch (IOException e) {

      /* Ignore */

    }



    /* Cleanup */

    finally {

      if (writer != null) {

        try {

          writer.close();

        } catch (IOException e) {

          /* Ignore */

        }

      }

    }

  }



  /* Find BASE-Information from Elements */

  private String getBase(Object elements[]) {

    for (Object object : elements) {

      if (object instanceof INews) {

        INews news = (INews) object;



        /* Base-Information explicitly set */

        if (news.getBase() != null)

          return news.getBase().toString();



        /* Use Feed's Link as fallback */

        return news.getFeedLinkAsText();

      }

    }



    return null;

  }



  private String unicodeToEntities(String str) {

    StringBuilder strBuf = new StringBuilder();



    /* For each character */

    for (int i = 0; i < str.length(); i++) {

      char ch = str.charAt(i);



      /* This is a non ASCII, non Whitespace character */

      if (!((ch >= 0x0020) && (ch <= 0x007e)) && !Character.isWhitespace(ch)) {

        strBuf.append("&#x"); //$NON-NLS-1$

        String hex = Integer.toHexString(ch & 0xFFFF);



        if (hex.length() == 2)

          strBuf.append("00"); //$NON-NLS-1$



        strBuf.append(hex).append(";"); //$NON-NLS-1$

      }



      /* This is an ASCII character */

      else {

        strBuf.append(ch);

      }

    }

    return strBuf.toString();

  }



  /**

   * @return the port used by this server.

   */

  public int getPort() {

    return SOCKET_PORT;

  }



  /**

   * @return the host used by this server.

   */

  public String getHost() {

    return LOCALHOST;

  }

}