src/main/java/at/ac/tuwien/sbc/valesriegler/xvsm/SpaceListener.java

   1 package at.ac.tuwien.sbc.valesriegler.xvsm;
   2
   3 import java.io.Serializable;
   4 import java.util.Date;
   5 import java.util.List;
   6 import java.util.Timer;
   7 import java.util.TimerTask;
   8
   9 import org.mozartspaces.notifications.Notification;
  10 import org.mozartspaces.notifications.NotificationListener;
  11 import org.mozartspaces.notifications.Operation;
  12 import org.slf4j.Logger;
  13 import org.slf4j.LoggerFactory;
  14
  15 /**
  16  *
  17  * The SpaceListener provides the {@link NotificationListener} interface.
  18  * <p />
  19  * In {@link SpaceListener#getEntries()} a method for reading the entities, that are normally expected from the notification,
  20  * must be supplied. Thus, it's possible in {@link SpaceListener#startHandlingAbsenceOfNotifications()} to start a timer and to
  21  * execute the actions, which are normally triggered by the notification, with space objects read from {@link SpaceListener#getEntries()}.
  22  * If {@link SpaceListener#lookAround} is true the timer periodically checks if the corresponding {@link AbstractXVSMConnector#timeOflastOperation} is old enough (= the agent is idle for some time)
  23  * and possibly executes the action as a result.
  24  *
  25  * @author Gregor Riegler <gregor DOT riegler AT gmail DOT com>
  26  *
  27  */
  28 public abstract class SpaceListener implements NotificationListener {
  29         private static final Logger log = LoggerFactory
  30                         .getLogger(SpaceListener.class);
  31
  32         protected boolean lookAround = true;
  33
  34         @Override
  35         public void entryOperationFinished(Notification arg0, Operation arg1,
  36                         List<? extends Serializable> entries) {
  37                 synchronized (AbstractXVSMConnector.lockObject) {
  38                         try {
  39                                 onEntriesWritten(entries);
  40                         } catch (Exception e) {
  41 //                              e.printStackTrace();
  42                         }
  43                         AbstractXVSMConnector.timeOflastOperation = new Date().getTime();
  44                 }
  45         }
  46
  47         abstract List<? extends Serializable> getEntries() throws Exception;
  48
  49         abstract void onEntriesWritten(List<? extends Serializable> entries)
  50                         throws Exception;
  51
  52         public void startHandlingAbsenceOfNotifications() {
  53                 if(!lookAround) return;
  54
  55                 Timer timer = new Timer();
  56
  57                 timer.schedule(new SpaceTask(), 500, 3000);
  58         }
  59
  60         class SpaceTask extends TimerTask {
  61
  62                 @Override
  63                 public void run() {
  64                         long time = new Date().getTime();
  65                         if(time-3000 <= AbstractXVSMConnector.timeOflastOperation) return;
  66                         synchronized(AbstractXVSMConnector.lockObject) {
  67                                 try {
  68
  69                                                 List<? extends Serializable> entries = getEntries();
  70                                                 if(entries.size() != 0) {
  71                                                         onEntriesWritten(entries);
  72                                                 }
  73                                 } catch (Exception e) {
  74                                         log.info(e.getMessage());
  75 //                                      e.printStackTrace();
  76                                 }
  77                                 AbstractXVSMConnector.timeOflastOperation = new Date().getTime();
  78                         }
  79
  80                 }
  81         }
  82
  83 }
  84
  85
  86