public final static String INTENT_TASKID = "taskId";

    public final static String INTENT_TASK = "task";

    public static final String PREF_DOWNLOADED = "downloaded";

    public static final int MSG_CANCEL = 0;

    public static final int MSG_UNREGISTER_CLIENT = 2;

    public final static int MSG_ADDTASK = 4;

    public static final int NOTIFICATION_PROCESSING = 0;

    public static final int NOTIFICATION_DONE = 1;

    private DownloadAsyncTask asyncExecutor;

    private DownloadHandler handler = new DownloadHandler();

    private final Messenger messenger = new Messenger(handler);

    private NotificationManager nM;

    private RemoteViews contentView;

    private LinkedList<DownloadTask> downloadTasks = new LinkedList<DownloadTask>();

    private DownloadTask currentTask = null;

    public class DownloadHandler extends Handler{

        public void handleMessage(Message msg){

            if(msg.obj != null){

                DownloadPackage pack = (DownloadPackage) msg.obj;

                DownloadTask task = null;

                Messenger replyToMessenger = msg.replyTo;

                for(DownloadTask _task : downloadTasks){

                    if(_task.getPackage().equals(pack)){

                        task = _task;

                        break;

                    }

                }

                switch(msg.what){

                case MSG_ADDTASK:

                    if(task == null){

                        task = new DownloadTask(pack);

                        downloadTasks.add(task);

                    }

                    task.addClient(replyToMessenger);

                    runNextTask();

                    return;

                case MSG_CANCEL:

                    if(task != null && task.getPackage().equals(pack) && task.getStatus() == TASK_STATE.PENDING){

                        downloadTasks.remove(task);

                    }

                    if(currentTask != null && currentTask.getPackage().equals(pack)){//TODO synchronization problem?

                        asyncExecutor.cancel(false);

                    }

                    return;

                case MSG_UNREGISTER_CLIENT:

                    if(task != null){

                        task.removeClient(replyToMessenger);

                    }

                    return;

                }

            }

        }

    }

    public void onCreate(){

        super.onCreate();

        nM = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

    }

    public IBinder onBind(Intent intent) {

        return messenger.getBinder();

    }

    private void runNextTask(){

        if(asyncExecutor == null){//if (task isnt running right now) ...

            currentTask = downloadTasks.poll();

            if(currentTask != null){

                asyncExecutor = new DownloadAsyncTask(currentTask);

                asyncExecutor.execute(currentTask.getPackage());

            }

        }

    }

    public void onDestroy(){

        super.onDestroy();

        asyncExecutor.cancel(false);

    }

    class DownloadTask {

        private final DownloadPackage pack;

        private TASK_STATE status = TASK_STATE.PENDING;

        private Notification progressNotification, doneNotification;

        //I expect little to no removeClient calls that's why we go for a list rather than a map

        private final List<Messenger> clients;

        public DownloadTask(DownloadPackage _pack){

            pack = _pack;

            clients = new LinkedList<Messenger>();

        }

        public void addClient(Messenger messenger){

            clients.add(messenger);

        }

        public void removeClient(Messenger messenger){

            clients.remove(messenger);

        }

        public DownloadPackage getPackage(){

            return pack;

        }

        public TASK_STATE getStatus(){

            return status;

        }

        public void sendMessageToClients(Message msg){

            for(Messenger messenger : clients){

                try {

                    messenger.send(msg);

                } catch (RemoteException e) {

                    e.printStackTrace();

                }

            }

        }

        /*

         * Callbacks called from the async tasks

         */

        //Thread safe method to let clients know the processing is starting and will process int max kbytes

        public void start(int max){

            progressNotification = new Notification(R.drawable.statusbar, getString(R.string.notification_title), System.currentTimeMillis());

            progressNotification.flags |= Notification.FLAG_ONGOING_EVENT;

            contentView = new RemoteViews(getPackageName(), R.layout.notification);

            contentView.setProgressBar(R.id.notification_progress, 100, 34, false);

            progressNotification.contentView = contentView;

            PendingIntent contentIntent = PendingIntent.getActivity(DownloadService.this, 0, new Intent(DownloadService.this, DownloadListActivity.class), Intent.FLAG_ACTIVITY_NEW_TASK);

            progressNotification.contentIntent = contentIntent;

            startForeground(NOTIFICATION_PROCESSING, progressNotification);

            Message msg = Message.obtain(null, DownloadFragment.MSG_START, max, 0);

            sendMessageToClients(msg);

        }

        //periodically gets called by the ASyncTask, we can't tell for sure when it's called

        public void update(int progress, int max, String fileName){

            progress = (progress/1024);

            contentView.setProgressBar(R.id.notification_progress, max, progress, false);

            contentView.setTextViewText(R.id.progressbar_sub, String.format("%dkb/%dkb (Compressed sizes)", progress, max));

            nM.notify(NOTIFICATION_PROCESSING, progressNotification);

            sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_UPDATE, progress, max, fileName));

        }

        //Call back from the ASync task when the task has either run into an error or finished otherwise

        public void done(int result){

            switch(result){

            case DownloadAsyncTask.EXIT_SUCCESS:    sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_DONE)); break;

            case DownloadAsyncTask.EXIT_CONNERROR:  sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_FAILED, DownloadAsyncTask.EXIT_CONNERROR, 0)); break;

            case DownloadAsyncTask.EXIT_FNF:        sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_FAILED, DownloadAsyncTask.EXIT_FNF, 0)); break;

            case DownloadAsyncTask.EXIT_MD5:        sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_FAILED, DownloadAsyncTask.EXIT_MD5, 0)); break;

            case DownloadAsyncTask.EXIT_URLFAIL:    sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_FAILED, DownloadAsyncTask.EXIT_URLFAIL, 0)); break;

            case DownloadAsyncTask.EXIT_CANCELLED:  sendMessageToClients(Message.obtain(handler, DownloadFragment.MSG_DONE)); break;

            }

            stopForeground(true);

            nM.cancel(NOTIFICATION_PROCESSING);

            String title = getString(R.string.notification_title);

            doneNotification = new Notification(R.drawable.icon, title, System.currentTimeMillis());

            doneNotification.flags |= Notification.FLAG_AUTO_CANCEL;

            PendingIntent contentIntent = PendingIntent.getActivity(DownloadService.this, 0, new Intent(DownloadService.this, DownloadListActivity.class), Intent.FLAG_ACTIVITY_NEW_TASK);

            doneNotification.setLatestEventInfo(DownloadService.this, title, getString(R.string.notification_done) + pack, contentIntent);

            nM.notify(pack.getId(), doneNotification);

            asyncExecutor = null;

            runNextTask();//see if there are more tasks

        }

    }

    enum TASK_STATE{

        RUNNING, FINISHED, PENDING;

    }