Improves error handling (foreground still needs testing).

add-on/src/addon/javascript/background.js

@@ -125,6 +125,18 @@ var listeners = [function (message, returnValue) {
         case "CommandQuit":
             returnValue = quit();
             break;
+        case "CommandError":
+            console.error("Error message", message);
+            if (message.forward)
+            {
+                returnValue = queryTab(message);
+            }
+            else
+            {
+                throw new TypeError("This is a background test");
+                returnValue = false;
+            }
+            break;
         }
     }
     else if (message == "quit")
@@ -202,7 +214,19 @@ interfacePort.onMessage.addListener((message) => {
         console.log("Sending ", returnValue)
         interfacePort.postMessage(returnValue);
     }).catch(error => {
-        console.error("Error in evaluating message: ", error)
+//        console.error("Error in evaluating message: ", error);
+        interfacePort.postMessage({
+            "messageNum": message.messageNum,
+            "message": {
+                "type": "edu.regis.universeplayer.browserCommands.CommandReturn",
+                "returnValue": null,
+                "confirmation": {
+                    type: "edu.regis.universeplayer.browserCommands.CommandConfirmation",
+                    message: "Error in executing request",
+                    errorCode: JSON.parse(JSON.stringify(error, Object.getOwnPropertyNames(error)))
+                }
+            }
+        });
     });
 });
 

add-on/src/addon/javascript/foreground.js

@@ -30,6 +30,9 @@ function handleMessage(message)
             return false;
         case "CommandSeek":
             return seek(message.time);
+        case "CommandError":
+            throw new TypeError("This is a foreground test");
+            return false;
         }
     }
 }

addonInter/src/main/java/edu/regis/universeplayer/addon/BrowserLink.java

@@ -5,6 +5,8 @@
 package edu.regis.universeplayer.addon;
 
 import com.google.gson.*;
+
+import edu.regis.universeplayer.browserCommands.CommandConfirmation;
 import edu.regis.universeplayer.browserCommands.MessageRunner;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -266,4 +268,10 @@ public class BrowserLink extends MessageRunner
         }
         return returnValue;
     }
+
+    @Override
+    public Object getErrorObject(Throwable e)
+    {
+        return new CommandConfirmation(e);
+    }
 }

addonInter/src/main/java/edu/regis/universeplayer/addon/ThrowableSerializer.java

@@ -21,7 +21,7 @@ public class ThrowableSerializer implements JsonSerializer<Throwable>, JsonDeser
         {
             stack.add(context.serialize(trace));
         }
-        ob.add("trace", stack);
+        ob.add("stack", stack);
         JsonArray suppressed = new JsonArray();
         for (Throwable throwable: src.getSuppressed())
         {
@@ -35,19 +35,37 @@ public class ThrowableSerializer implements JsonSerializer<Throwable>, JsonDeser
     public Throwable deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException
     {
         JsonObject ob = json.getAsJsonObject();
-        Throwable throwable = new Throwable(ob.get("message").getAsString(), context.deserialize(ob.get("cause"), typeOfT));
+        Throwable cause = context.deserialize(ob.get("cause"), typeOfT);
+        Throwable throwable;
+        if (cause == null)
+        {
+            throwable = new Throwable(ob.get("message").getAsString());
+        }
+        else
+        {
+            throwable = new Throwable(ob.get("message").getAsString(), context
+                    .deserialize(ob.get("cause"), typeOfT));
             throwable.initCause(context.deserialize(ob.get("cause"), Throwable.class));
-        JsonArray traceJson = ob.getAsJsonArray("trace");
+        }
+        JsonArray traceJson = ob.getAsJsonArray("stack");
+        if (traceJson != null)
+        {
             StackTraceElement[] trace = new StackTraceElement[traceJson.size()];
             for (int i = 0; i < trace.length; i++)
             {
-            trace[i] = context.deserialize(traceJson.get(i), StackTraceElement.class);
+                trace[i] = context
+                        .deserialize(traceJson.get(i), StackTraceElement.class);
             }
             throwable.setStackTrace(trace);
+        }
         JsonArray suppressed = ob.getAsJsonArray("suppressed");
-        for (JsonElement el: suppressed)
+        if (suppressed != null)
         {
-            throwable.addSuppressed(context.deserialize(el, Throwable.class));
+            for (JsonElement el : suppressed)
+            {
+                throwable.addSuppressed(context
+                        .deserialize(el, Throwable.class));
+            }
         }
         return throwable;
     }

browserCommands/src/main/java/edu/regis/universeplayer/browserCommands/CommandError.java

@@ -0,0 +1,44 @@
+package edu.regis.universeplayer.browserCommands;
+
+/**
+ * A debugging command that instructs the browser to throw an error.
+ */
+public class CommandError implements BrowserCommand
+{
+    private boolean forward;
+
+    /**
+     * Creates an error command.
+     *
+     * @param forward - Determines where the error should be thrown. If true, it
+     *                will be thrown from the website tab. If false, it will be
+     *                thrown by the addon background script.
+     */
+    public CommandError(boolean forward)
+    {
+        this.forward = forward;
+    }
+
+    /**
+     * Checks whether the error will be thrown from the foreground or background
+     * script.
+     *
+     * @return True if the error will be thrown from the foreground script,
+     * false if it will be thrown from the background.
+     */
+    public boolean isForeground()
+    {
+        return this.forward;
+    }
+
+    /**
+     * Obtains the name of the command.
+     *
+     * @return The command name.
+     */
+    @Override
+    public String getCommandName()
+    {
+        return "error";
+    }
+}

browserCommands/src/main/java/edu/regis/universeplayer/browserCommands/MessageHandler.java

@@ -99,17 +99,27 @@ public class MessageHandler implements Runnable, MessageSerializer
                         {
                             numBuffer.clear();
                             numBuffer.put(message[0]);
+                            try
+                            {
                                 messageOb = this.deserializeObject(message[1]);
-                            messageResponse = this.triggerListeners(messageOb);
+                            }
+                            catch (IOException | ClassNotFoundException e)
+                            {
+                                logger.error("Could not read message", e);
+                                messageOb = this.getErrorObject(e);
+                            }
+                            messageResponse = this
+                                    .triggerListeners(messageOb);
                             synchronized (this.messageResponses)
                             {
                                 numBuffer.clear();
-                                this.messageResponses.put(numBuffer.getInt(), messageResponse);
+                                this.messageResponses.put(numBuffer
+                                        .getInt(), messageResponse);
                             }
                         }
                     }
                 }
-                catch (IOException | ClassNotFoundException e)
+                catch (IOException e)
                 {
                     logger.error("Could not retrieve message", e);
                     running = false;

browserCommands/src/main/java/edu/regis/universeplayer/browserCommands/MessageSerializer.java

@@ -37,7 +37,8 @@ public interface MessageSerializer
      *
      * @param message - The message received.
      * @return An object.
-     * @throws IOException            If there is an error in parsing the message.
+     * @throws IOException            If there is an error in parsing the
+     *                                message.
      * @throws ClassNotFoundException If the object is not recognized
      */
     default Object deserializeObject(byte[] message) throws IOException, ClassNotFoundException
@@ -55,7 +56,8 @@ public interface MessageSerializer
      * Writes a message to the output stream.
      *
      * @param out        - The output stream to write to.
-     * @param messageNum - The ID of the message being sent. This will help keep track of responses.
+     * @param messageNum - The ID of the message being sent. This will help keep
+     *                   track of responses.
      * @param message    - The actual message contents to write.
      * @throws IOException Thrown when an exception occures
      */
@@ -119,7 +121,8 @@ public interface MessageSerializer
         readLength = in.read(lengthBuffer.array());
         if (readLength == 0)
         {
-            getLogger().error("Malformed message, could not get message length.");
+            getLogger()
+                    .error("Malformed message, could not get message length.");
             return null;
         }
         message = new byte[lengthBuffer.getInt()];
@@ -129,9 +132,21 @@ public interface MessageSerializer
         readLength = in.read(message);
         if (readLength < message.length)
         {
-            getLogger().warn("Message shorter than reported (expected {} bytes, got {} bytes)", message.length, readLength);
+            getLogger()
+                    .warn("Message shorter than reported (expected {} bytes, got {} bytes)", message.length, readLength);
         }
         getLogger().trace("Reading message");
-        return new byte[][] {messageNum, message};
+        return new byte[][]{messageNum, message};
+    }
+
+    /**
+     * This method is called when an error in deserialization occurs.
+     *
+     * @param e - The error thrown.
+     * @return An object to return to listeners in the event of a read error.
+     */
+    default Object getErrorObject(Throwable e)
+    {
+        return e;
     }
 }

interface/src/main/java/edu/regis/universeplayer/browser/BrowserPlayer.java

@@ -12,6 +12,7 @@ import edu.regis.universeplayer.browserCommands.*;
 import edu.regis.universeplayer.data.InternetSong;
 import edu.regis.universeplayer.data.PlaybackEvent;
 import edu.regis.universeplayer.data.Song;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -28,7 +29,8 @@ import java.util.concurrent.*;
  */
 public class BrowserPlayer implements Player<InternetSong>, UpdateListener
 {
-    private static final Logger logger = LoggerFactory.getLogger(BrowserPlayer.class);
+    private static final Logger logger = LoggerFactory
+            .getLogger(BrowserPlayer.class);
 
     private final LinkedList<PlaybackListener> listeners = new LinkedList<>();
 
@@ -68,7 +70,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandLoadSong(song.location)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandLoadSong(song.location)));
         }
         catch (IOException e)
         {
@@ -85,7 +88,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            QueryFuture<Void> future = new ForwardedFuture(getBrowser().sendObject(new CommandQuit()));
+            QueryFuture<Void> future = new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandQuit()));
             return future;
         }
         catch (IOException e)
@@ -134,7 +138,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PLAY)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PLAY)));
         }
         catch (IOException e)
         {
@@ -148,7 +153,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PAUSE)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PAUSE)));
         }
         catch (IOException e)
         {
@@ -162,7 +168,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PAUSE)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandSetPlayback(CommandSetPlayback.Playback.PAUSE)));
         }
         catch (IOException e)
         {
@@ -179,7 +186,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandLoadSong((URL) null)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandLoadSong((URL) null)));
         }
         catch (IOException e)
         {
@@ -193,7 +201,8 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
     {
         try
         {
-            return new ForwardedFuture(getBrowser().sendObject(new CommandSeek(time)));
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandSeek(time)));
         }
         catch (IOException e)
         {
@@ -290,6 +299,27 @@ public class BrowserPlayer implements Player<InternetSong>, UpdateListener
         return null;
     }
 
+    /**
+     * Causes the browser to throw an error
+     *
+     * @param forward - Whether the error should be thrown from the foreground
+     *                script or the background script.
+     * @return
+     */
+    public QueryFuture<Void> throwError(boolean forward)
+    {
+        try
+        {
+            return new ForwardedFuture(getBrowser()
+                    .sendObject(new CommandError(forward)));
+        }
+        catch (IOException e)
+        {
+            logger.error("Could not send message", e);
+            return null;
+        }
+    }
+
     @Override
     public void onUpdate(Object object, MessageRunner runner)
     {

interface/src/main/java/edu/regis/universeplayer/player/Interface.java

@@ -7,6 +7,8 @@ package edu.regis.universeplayer.player;
 import edu.regis.universeplayer.Player;
 import edu.regis.universeplayer.browser.Browser;
 import edu.regis.universeplayer.browser.BrowserPlayer;
+import edu.regis.universeplayer.browserCommands.CommandError;
+import edu.regis.universeplayer.browserCommands.QueryFuture;
 import edu.regis.universeplayer.data.InternetSong;
 import edu.regis.universeplayer.data.Queue;
 import edu.regis.universeplayer.data.*;
@@ -28,9 +30,11 @@ import java.util.Collection;
 import java.util.Locale;
 import java.util.ResourceBundle;
 import java.util.Set;
+import java.util.concurrent.ExecutionException;
 
 /**
- * The Interface class serves as the primary GUI that the player interacts with.
+ * The Interface class serves as the primary GUI that the player interacts
+ * with.
  *
  * @author William Hubbard
  * @version 0.1
@@ -40,7 +44,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
     //    static {
 //        Locale.setDefault(new Locale("es", "ES"));
 //    }
-    private static final Logger logger = LoggerFactory.getLogger(Interface.class);
+    private static final Logger logger = LoggerFactory
+            .getLogger(Interface.class);
     private static final ResourceBundle langs = ResourceBundle
             .getBundle("lang.interface", Locale.getDefault());
 
@@ -119,8 +124,10 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
                 inter.players.add(browserPlayer = new BrowserPlayer());
                 logger.debug("Sending ping");
                 browser.sendObject("ping");
-                Runtime.getRuntime().addShutdownHook(new Thread(browserPlayer::close));
+                Runtime.getRuntime()
-                Player.REGISTERED_PLAYERS.put(InternetSong.class, browserPlayer);
+                       .addShutdownHook(new Thread(browserPlayer::close));
+                Player.REGISTERED_PLAYERS
+                        .put(InternetSong.class, browserPlayer);
 
 //                LinkedList<Future<Object>> pingRequests = new LinkedList<>();
 //                for (int i = 0; i < 20; i++)
@@ -155,7 +162,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         {
             logger.error("Could not open browser background", e);
             JOptionPane
-                    .showMessageDialog(inter != null && inter.isVisible() ? inter : null, e, langs
+                    .showMessageDialog(inter != null && inter
+                            .isVisible() ? inter : null, e, langs
                             .getString("error.generic"), JOptionPane.ERROR_MESSAGE);
         }
     }
@@ -221,7 +229,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
             {
                 if (!commDir.getParentFile().mkdir())
                 {
-                    logger.error("Could not create shared directory {}", commDir.getParent());
+                    logger.error("Could not create shared directory {}", commDir
+                            .getParent());
                 }
             }
             if (!commDir.exists())
@@ -262,7 +271,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
     {
         AbstractAction action;
 
-        this.actions.put("refresh", action = new AbstractAction(langs.getString("actions.refresh"))
+        this.actions.put("refresh", action = new AbstractAction(langs
+                .getString("actions.refresh"))
         {
             @Override
             public void actionPerformed(ActionEvent e)
@@ -302,7 +312,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         });
         action.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_E);
 
-        this.actions.put("exit", action = new AbstractAction(langs.getString("actions.exit"))
+        this.actions.put("exit", action = new AbstractAction(langs
+                .getString("actions.exit"))
         {
             @Override
             public void actionPerformed(ActionEvent e)
@@ -316,7 +327,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         });
         action.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_X);
 
-        this.actions.put("logs", action = new AbstractAction(langs.getString("actions.logs"))
+        this.actions.put("logs", action = new AbstractAction(langs
+                .getString("actions.logs"))
         {
             @Override
             public void actionPerformed(ActionEvent e)
@@ -330,9 +342,114 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
                 }
             }
         });
-        action.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_F12, 0));
+        action.putValue(Action.ACCELERATOR_KEY, KeyStroke
+                .getKeyStroke(KeyEvent.VK_F12, 0));
 
-        this.actions.put("about", action = new AbstractAction(langs.getString("actions.about"))
+        this.actions.put("debug.error", action =
+                new AbstractAction(langs.getString("actions.debug.error"))
+                {
+                    @Override
+                    public void actionPerformed(ActionEvent e)
+                    {
+                        if (this.isEnabled())
+                        {
+                            new SwingWorker<Void, Void>()
+                            {
+                                /**
+                                 * Computes
+                                 * a
+                                 * result,
+                                 * or
+                                 * throws
+                                 * an
+                                 * exception
+                                 * if
+                                 * unable
+                                 * to
+                                 * do
+                                 * so.
+                                 *
+                                 * <p>
+                                 * Note
+                                 * that
+                                 * this
+                                 * method
+                                 * is
+                                 * executed
+                                 * only
+                                 * once.
+                                 *
+                                 * <p>
+                                 * Note:
+                                 * this
+                                 * method
+                                 * is
+                                 * executed
+                                 * in
+                                 * a
+                                 * background
+                                 * thread.
+                                 *
+                                 * @return the computed result
+                                 * @throws Exception if unable to compute a result
+                                 */
+                                @Override
+                                protected Void doInBackground() throws Exception
+                                {
+                                    Interface.this.players.stream()
+                                                          .filter(p -> p instanceof BrowserPlayer)
+                                                          .map(p -> (BrowserPlayer) p)
+                                                          .findFirst()
+                                                          .ifPresentOrElse(p -> {
+                                                              logger.debug("Throwing " +
+                                                                      "error");
+                                                              QueryFuture<Void> command = p
+                                                                      .throwError((false));
+                                                              try
+                                                              {
+                                                                  if (!command
+                                                                          .getConfirmation()
+                                                                          .wasSuccessful())
+                                                                  {
+                                                                      logger.error("Could not run command",
+                                                                              command.getConfirmation()
+                                                                                     .getError());
+                                                                      JOptionPane
+                                                                              .showMessageDialog(Interface.this,
+                                                                                      command.getConfirmation()
+                                                                                             .getError(),
+                                                                                      command.getConfirmation()
+                                                                                             .getMessage(),
+                                                                                      JOptionPane.ERROR_MESSAGE);
+                                                                  }
+                                                              }
+                                                              catch (ExecutionException | InterruptedException executionException)
+                                                              {
+                                                                  logger.error("Error" +
+                                                                          " creating " +
+                                                                          "debug " +
+                                                                          "message", executionException);
+                                                                  JOptionPane
+                                                                          .showMessageDialog(Interface.this, executionException
+                                                                                  .getMessage(), langs
+                                                                                  .getString(
+                                                                                          "error.command"), JOptionPane.ERROR_MESSAGE);
+                                                              }
+                                                          }, () -> JOptionPane
+                                                                  .showMessageDialog(Interface.this, langs
+                                                                          .getString("error.browser.null"), langs
+                                                                          .getString("error.debug.error"), JOptionPane.ERROR_MESSAGE));
+                                    return null;
+                                }
+                            }.execute();
+                        }
+                    }
+                });
+        action.putValue(Action.ACCELERATOR_KEY, KeyStroke
+                .getKeyStroke(KeyEvent.VK_F12, 0));
+
+        this.actions.put("about", action = new AbstractAction(langs
+                .getString("actions.about"))
         {
             @Override
             public void actionPerformed(ActionEvent e)
@@ -345,7 +462,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         });
 
         this.actions
-                .put("view.all", action = new AbstractAction(langs.getString("actions.view.all"))
+                .put("view.all", action = new AbstractAction(langs
+                        .getString("actions.view.all"))
                 {
                     @Override
                     public void actionPerformed(ActionEvent e)
@@ -521,7 +639,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
     protected void constructWindow()
     {
         JMenuBar toolbar;
-        JMenu fileMenu, viewMenu, collectionsMenu, playbackMenu, helpMenu;
+        JMenu fileMenu, viewMenu, collectionsMenu, playbackMenu, helpMenu,
+                debugMenu;
 
         this.setTitle(langs.getString("title"));
         this.getContentPane().setLayout(new BorderLayout());
@@ -569,6 +688,10 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         helpMenu.setMnemonic(KeyEvent.VK_H);
         toolbar.add(helpMenu);
 
+        debugMenu = new JMenu(langs.getString("menu.debug.title"));
+        debugMenu.setMnemonic(KeyEvent.VK_D);
+        helpMenu.add(debugMenu);
+
         fileMenu.add(new JMenuItem(actions.get("refresh")));
 
         fileMenu.add(actions.get("addExternal"));
@@ -590,6 +713,9 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
 
         helpMenu.add(new JMenuItem(actions.get("logs")));
 
+        helpMenu.add(debugMenu);
+        debugMenu.add(new JMenuItem(actions.get("debug.error")));
+
         helpMenu.add(new JMenuItem(actions.get("about")));
 
         this.setJMenuBar(toolbar);
@@ -606,15 +732,18 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         ((SortingFocusTraversalPolicy) this.getFocusTraversalPolicy())
                 .setImplicitDownCycleTraversal(true);
         this.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, Set
-                .of(AWTKeyStroke.getAWTKeyStroke(KeyEvent.VK_DOWN, 0), AWTKeyStroke
+                .of(AWTKeyStroke
+                        .getAWTKeyStroke(KeyEvent.VK_DOWN, 0), AWTKeyStroke
                         .getAWTKeyStroke(KeyEvent.VK_RIGHT, 0)));
         this.setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, Set
-                .of(AWTKeyStroke.getAWTKeyStroke(KeyEvent.VK_UP, 0), AWTKeyStroke
+                .of(AWTKeyStroke
+                        .getAWTKeyStroke(KeyEvent.VK_UP, 0), AWTKeyStroke
                         .getAWTKeyStroke(KeyEvent.VK_LEFT, 0)));
         this.setFocusTraversalKeys(KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, Set
                 .of(AWTKeyStroke.getAWTKeyStroke(KeyEvent.VK_TAB, 0)));
         this.setFocusTraversalKeys(KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS, Set
-                .of(AWTKeyStroke.getAWTKeyStroke(KeyEvent.VK_TAB, KeyEvent.SHIFT_DOWN_MASK)));
+                .of(AWTKeyStroke
+                        .getAWTKeyStroke(KeyEvent.VK_TAB, KeyEvent.SHIFT_DOWN_MASK)));
     }
 
     @Override
@@ -752,7 +881,8 @@ public class Interface extends JFrame implements SongDisplayListener, ComponentL
         else
         {
             int index = -1;
-            Component[] children = ((Container) e.getComponent()).getComponents();
+            Component[] children = ((Container) e.getComponent())
+                    .getComponents();
             for (int i = 0, l = children.length; index == -1 && i < l; i++)
             {
                 if (children[i] == e.getOppositeComponent())

interface/src/main/java/edu/regis/universeplayer/player/PlayerControls.java

@@ -8,31 +8,42 @@ import edu.regis.universeplayer.PlaybackInfo;
 import edu.regis.universeplayer.PlaybackListener;
 import edu.regis.universeplayer.PlaybackStatus;
 import edu.regis.universeplayer.Player;
+import edu.regis.universeplayer.browserCommands.CommandConfirmation;
+import edu.regis.universeplayer.browserCommands.CommandReturn;
+import edu.regis.universeplayer.browserCommands.QueryFuture;
 import edu.regis.universeplayer.data.PlaybackEvent;
 import edu.regis.universeplayer.data.Queue;
 import edu.regis.universeplayer.data.Song;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import javax.swing.*;
+
 import java.awt.*;
 import java.awt.event.FocusAdapter;
 import java.awt.event.FocusEvent;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.util.LinkedList;
+import java.util.Locale;
+import java.util.ResourceBundle;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ForkJoinPool;
 
 /**
- * This panel contains the buttons necessary for controlling the playback of audio.
+ * This panel contains the buttons necessary for controlling the playback of
+ * audio.
  *
  * @author William Hubbard
  * @version 0.1
  */
 public class PlayerControls extends JPanel implements Queue.SongChangeListener, PlaybackListener
 {
-    private static final Logger logger = LoggerFactory.getLogger(PlayerControls.class);
+    private static final Logger logger = LoggerFactory
+            .getLogger(PlayerControls.class);
+    private static final ResourceBundle langs = ResourceBundle
+            .getBundle("lang.interface", Locale.getDefault());
     private final ImageIcon PLAY_ICON, PAUSE_ICON;
 
     /**
@@ -72,29 +83,39 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
         buttonCont = new JPanel(buttonLayout);
         this.add(buttonCont);
 
-        this.prevButton = new JButton(Interface.getInstance().actions.get("playback.skipPrev"));
+        this.prevButton = new JButton(Interface.getInstance().actions
+                .get("playback.skipPrev"));
         this.prevButton.setText("");
         icon = new ImageIcon(this.getClass()
                                  .getResource("/gui/icons/skipPrev.png"), "Previous Button");
-        icon.setImage(icon.getImage().getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
+        icon.setImage(icon.getImage()
+                          .getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
         this.prevButton.setIcon(icon);
         this.prevButton.setPreferredSize(BUTTON_SIZE);
         buttonCont.add(this.prevButton);
 
-        this.playButton = new JButton(Interface.getInstance().actions.get("playback.toggle"));
+        this.playButton = new JButton(Interface.getInstance().actions
+                .get("playback.toggle"));
         this.playButton.setText("");
-        PAUSE_ICON = icon = new ImageIcon(this.getClass().getResource("/gui/icons/pause.png"), "Pause Button");
+        PAUSE_ICON = icon = new ImageIcon(this.getClass()
-        icon.setImage(icon.getImage().getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
+                                              .getResource("/gui/icons/pause.png"), "Pause Button");
-        PLAY_ICON = icon = new ImageIcon(this.getClass().getResource("/gui/icons/play.png"), "Play Button");
+        icon.setImage(icon.getImage()
-        icon.setImage(icon.getImage().getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
+                          .getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
+        PLAY_ICON = icon = new ImageIcon(this.getClass()
+                                             .getResource("/gui/icons/play.png"), "Play Button");
+        icon.setImage(icon.getImage()
+                          .getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
         this.playButton.setIcon(icon);
         this.playButton.setPreferredSize(BUTTON_SIZE);
         buttonCont.add(this.playButton);
 
-        this.nextButton = new JButton(Interface.getInstance().actions.get("playback.skipNext"));
+        this.nextButton = new JButton(Interface.getInstance().actions
+                .get("playback.skipNext"));
         this.nextButton.setText("");
-        icon = new ImageIcon(this.getClass().getResource("/gui/icons/skipNext.png"), "Next Button");
+        icon = new ImageIcon(this.getClass()
-        icon.setImage(icon.getImage().getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
+                                 .getResource("/gui/icons/skipNext.png"), "Next Button");
+        icon.setImage(icon.getImage()
+                          .getScaledInstance(ICON_SIZE.width, ICON_SIZE.height, 0));
         this.nextButton.setIcon(icon);
         this.nextButton.setPreferredSize(BUTTON_SIZE);
         buttonCont.add(this.nextButton);
@@ -109,7 +130,9 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             @Override
             public void mouseClicked(MouseEvent e)
             {
-                seek((float) e.getX() / (float) e.getComponent().getWidth() * ((JProgressBar) e.getComponent()).getMaximum());
+                seek((float) e.getX() / (float) e.getComponent()
+                                                 .getWidth() * ((JProgressBar) e
+                        .getComponent()).getMaximum());
                 logger.debug("Changing time");
             }
         });
@@ -126,7 +149,8 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             public void focusGained(FocusEvent e)
             {
                 int index = -1;
-                Component[] children = ((Container) e.getComponent()).getComponents();
+                Component[] children = ((Container) e.getComponent())
+                        .getComponents();
                 for (int i = 0, l = children.length; index == -1 && i < l; i++)
                 {
                     if (children[i] == e.getOppositeComponent())
@@ -166,7 +190,26 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
         this.service.execute(() -> {
             if (this.currentPlayer != null)
             {
-                this.currentPlayer.seek(value);
+                QueryFuture<Void> command = this.currentPlayer.seek(value);
+                try
+                {
+                    if (!command.getConfirmation().wasSuccessful())
+                    {
+                        JOptionPane.showMessageDialog(this,
+                                command.getConfirmation().getError(),
+                                command.getConfirmation().getMessage(),
+                                JOptionPane.ERROR_MESSAGE);
+                        logger.error("Could not run command",
+                                command.getConfirmation().getError());
+                    }
+                }
+                catch (ExecutionException | InterruptedException e)
+                {
+                    logger.error("Could not run command", e);
+                    JOptionPane.showMessageDialog(this, e.getMessage(), langs
+                            .getString(
+                                    "error.command"), JOptionPane.ERROR_MESSAGE);
+                }
             }
         });
         this.triggerCommandListeners(PlaybackCommand.SEEK, value);
@@ -179,28 +222,49 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             {
                 if (this.currentPlayer != null)
                 {
-                    switch ((PlaybackStatus) this.currentPlayer.getStatus().get())
+                    QueryFuture<PlaybackStatus> status =
+                            this.currentPlayer.getStatus();
+                    CommandConfirmation confirmation = status.getConfirmation();
+                    if (status.getConfirmation().wasSuccessful())
                     {
-                    case PAUSED -> this.currentPlayer.play();
+                        switch (status.get())
+                        {
+                        case PAUSED -> confirmation = this.currentPlayer.play()
+                                                                    .getConfirmation();
                         case STOPPED, EMPTY -> {
                             if (Queue.getInstance().size() > 0)
                             {
-                            if (Queue.getInstance().getCurrentSong() == null)
+                                if (Queue.getInstance()
+                                         .getCurrentSong() == null)
                                 {
                                     Queue.getInstance().skipToSong(0);
                                 }
                                 else
                                 {
-                                this.currentPlayer.play();
+                                    confirmation = this.currentPlayer.play()
+                                                                     .getConfirmation();
                                 }
                             }
                         }
                         }
                     }
+                    if (confirmation != null && !confirmation.wasSuccessful())
+                    {
+                        JOptionPane.showMessageDialog(this,
+                                confirmation.getError(),
+                                confirmation.getMessage(),
+                                JOptionPane.ERROR_MESSAGE);
+                        logger.error("Could not run command",
+                                confirmation.getError());
+                    }
+                }
             }
             catch (ExecutionException | InterruptedException e)
             {
                 logger.error("Could not get current playback status", e);
+                JOptionPane.showMessageDialog(this, e.getMessage(), langs
+                        .getString(
+                                "error.command"), JOptionPane.ERROR_MESSAGE);
             }
         });
         this.triggerCommandListeners(PlaybackCommand.PLAY, null);
@@ -213,15 +277,34 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             {
                 if (this.currentPlayer != null)
                 {
-                    switch ((PlaybackStatus) this.currentPlayer.getStatus().get())
+                    QueryFuture<PlaybackStatus> status =
+                            this.currentPlayer.getStatus();
+                    CommandConfirmation confirmation = status.getConfirmation();
+                    if (status.getConfirmation().wasSuccessful())
                     {
-                    case PLAYING -> this.currentPlayer.pause();
+                        switch (status.get())
+                        {
+                        case PLAYING -> confirmation =
+                                this.currentPlayer.pause().getConfirmation();
+                        }
+                    }
+                    if (confirmation != null && !confirmation.wasSuccessful())
+                    {
+                        JOptionPane.showMessageDialog(this,
+                                confirmation.getError(),
+                                confirmation.getMessage(),
+                                JOptionPane.ERROR_MESSAGE);
+                        logger.error("Could not run command",
+                                confirmation.getError());
                     }
                 }
             }
             catch (ExecutionException | InterruptedException e)
             {
                 logger.error("Could not get current playback status", e);
+                JOptionPane.showMessageDialog(this, e.getMessage(), langs
+                        .getString(
+                                "error.command"), JOptionPane.ERROR_MESSAGE);
             }
         });
         this.triggerCommandListeners(PlaybackCommand.PAUSE, null);
@@ -237,29 +320,51 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             {
                 if (this.currentPlayer != null)
                 {
-                    switch ((PlaybackStatus) this.currentPlayer.getStatus().get())
+                    QueryFuture<PlaybackStatus> status =
+                            this.currentPlayer.getStatus();
+                    CommandConfirmation confirmation = status.getConfirmation();
+                    if (status.getConfirmation().wasSuccessful())
                     {
-                    case PAUSED -> this.currentPlayer.play();
+                        switch (status.get())
-                    case PLAYING -> this.currentPlayer.pause();
+                        {
+                        case PAUSED -> confirmation = this.currentPlayer.play()
+                                                                    .getConfirmation();
+                        case PLAYING -> confirmation = this.currentPlayer.pause()
+                                                                     .getConfirmation();
                         case STOPPED, EMPTY -> {
                             if (Queue.getInstance().size() > 0)
                             {
-                            if (Queue.getInstance().getCurrentSong() == null)
+                                if (Queue.getInstance()
+                                         .getCurrentSong() == null)
                                 {
                                     Queue.getInstance().skipToSong(0);
                                 }
                                 else
                                 {
-                                this.currentPlayer.play();
+                                    confirmation = this.currentPlayer.play()
+                                                                     .getConfirmation();
                                 }
                             }
                         }
                         }
                     }
+                    if (confirmation != null && !confirmation.wasSuccessful())
+                    {
+                        JOptionPane.showMessageDialog(this,
+                                confirmation.getError(),
+                                confirmation.getMessage(),
+                                JOptionPane.ERROR_MESSAGE);
+                        logger.error("Could not run command",
+                                confirmation.getError());
+                    }
+                }
             }
             catch (ExecutionException | InterruptedException e)
             {
                 logger.error("Could not get current playback status", e);
+                JOptionPane.showMessageDialog(this, e.getMessage(), langs
+                        .getString(
+                                "error.command"), JOptionPane.ERROR_MESSAGE);
             }
         });
         this.triggerCommandListeners(PlaybackCommand.PLAY, null);
@@ -349,14 +454,37 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
         {
             if (this.currentPlayer != null)
             {
-                this.currentPlayer.stopSong();
+                this.service.execute(() -> {
+                    QueryFuture<Void> command = this.currentPlayer.stopSong();
+                    try
+                    {
+                        if (!command.getConfirmation().wasSuccessful())
+                        {
+                            JOptionPane.showMessageDialog(this,
+                                    command.getConfirmation().getError(),
+                                    command.getConfirmation().getMessage(),
+                                    JOptionPane.ERROR_MESSAGE);
+                            logger.error("Could not run command",
+                                    command.getConfirmation().getError());
+                        }
+                    }
+                    catch (ExecutionException | InterruptedException e)
+                    {
+                        logger.error("Could not get current playback status", e);
+                        JOptionPane
+                                .showMessageDialog(this, e.getMessage(), langs
+                                        .getString(
+                                                "error.command"), JOptionPane.ERROR_MESSAGE);
+                    }
+                });
             }
         }
         this.currentSong = queue.getCurrentSong();
         this.playButton.setIcon(PLAY_ICON);
         if (this.currentSong != null)
         {
-            this.currentPlayer = Player.REGISTERED_PLAYERS.get(this.currentSong.getClass());
+            this.currentPlayer = Player.REGISTERED_PLAYERS
+                    .get(this.currentSong.getClass());
             this.progress.setMaximum((int) (this.currentSong.duration / 1000));
             if (this.currentPlayer != null)
             {
@@ -364,12 +492,37 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
                 {
                     this.currentPlayer.addPlaybackListener(this);
                 }
+                this.service.execute(() -> {
+                    QueryFuture<Void> command =
                             this.currentPlayer.loadSong(this.currentSong);
+                    try
+                    {
+                        if (!command.getConfirmation().wasSuccessful())
+                        {
+                            JOptionPane.showMessageDialog(this,
+                                    command.getConfirmation().getError(),
+                                    command.getConfirmation().getMessage(),
+                                    JOptionPane.ERROR_MESSAGE);
+                            logger.error("Could not run command",
+                                    command.getConfirmation().getError());
+                        }
+                    }
+                    catch (ExecutionException | InterruptedException e)
+                    {
+                        logger.error("Could not get current playback status", e);
+                        JOptionPane
+                                .showMessageDialog(this, e.getMessage(), langs
+                                        .getString(
+                                                "error.command"), JOptionPane.ERROR_MESSAGE);
+                    }
+                });
+
 //                this.currentPlayer.play();
             }
             else
             {
-                logger.error("No logger found for song {}", this.currentSong.getClass());
+                logger.error("No logger found for song {}", this.currentSong
+                        .getClass());
             }
         }
         else
@@ -382,7 +535,8 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
     @Override
     public void onPlaybackChanged(PlaybackEvent status)
     {
-        if (status.getSource() != null && status.getSource() == this.currentPlayer)
+        if (status.getSource() != null && status
+                .getSource() == this.currentPlayer)
         {
             switch (status.getInfo().getStatus())
             {
@@ -391,7 +545,8 @@ public class PlayerControls extends JPanel implements Queue.SongChangeListener,
             case PAUSED, STOPPED, EMPTY -> this.playButton.setIcon(PLAY_ICON);
             }
             this.progress.setValue((int) status.getInfo().getPlayTime());
-            this.progress.setMaximum((int) (status.getInfo().getSong().duration / 1000));
+            this.progress.setMaximum((int) (status.getInfo()
+                                                  .getSong().duration / 1000));
         }
     }
 }

interface/src/main/resources/lang/interface.properties

@@ -14,6 +14,7 @@ menu.view.title=View
 menu.view.collections=Collections
 menu.playback.title=Playback
 menu.help.title=Help
+menu.debug.title=Debugging
 
 albumInfo.album=Album
 albumInfo.artists=Artists
@@ -42,6 +43,7 @@ actions.refresh=Refresh Song Cache
 actions.exit=Exit
 
 actions.logs=Show Logs
+actions.debug.error=Throw Error
 
 actions.about=About
 
@@ -61,4 +63,7 @@ actions.playback.skipPrev=Skip Previously
 actions.playback.skipNext=Skip Next
 
 error.generic=Error!
+error.command=Could not run command
+error.debug.error=Could not create error
 error.browser.launch=Could not open browser background
+error.browser.null=Could not find browser background