started adding WindListener pattern to NMEAWindReceiver

Change-Id: Idbdd0b205370f32a3282a418fc9600d226a6313a

java/com.sap.sailing.nmeaconnector/src/com/sap/sailing/nmeaconnector/NMEAWindReceiver.java

@@ -1,5 +1,9 @@
 package com.sap.sailing.nmeaconnector;
 
+import com.sap.sailing.domain.common.Wind;
+import com.sap.sailing.domain.tracking.WindListener;
+import com.sap.sse.common.TimePoint;
+
 import net.sf.marineapi.nmea.event.SentenceListener;
 import net.sf.marineapi.nmea.io.SentenceReader;
 import net.sf.marineapi.nmea.sentence.DateSentence;
@@ -12,7 +16,9 @@ import net.sf.marineapi.nmea.sentence.TimeSentence;
  * for which it acts as a {@link SentenceListener} for sentences providing information
  * about wind measurements, date/time reference, location of measurements and data
  * that may be required to convert apparent wind speeds and angles into true wind
- * speeds and directions.<p>
+ * speeds and directions. Clients can {@link #addWindListener(WindListener) register}
+ * as a {@link WindListener} and receive {@link WindListener#windDataReceived} callbacks
+ * whenever a {@link Wind} fix was assembled out of the various NMEA sentences.<p>
  * 
  * The NMEA 0183 protocol specifies that a {@link SentenceId#MWV} sentence may provide
  * "true" (relative to true north) or "relative" (relative to bow) wind angles. However,
@@ -41,5 +47,7 @@ import net.sf.marineapi.nmea.sentence.TimeSentence;
  *
  */
 public interface NMEAWindReceiver {
-
+    void addWindListener(WindListener listener);
+    
+    void removeWindListener(WindListener listener);
 }

java/com.sap.sailing.nmeaconnector/src/com/sap/sailing/nmeaconnector/impl/NMEAWindReceiverImpl.java

@@ -1,7 +1,32 @@
 package com.sap.sailing.nmeaconnector.impl;
 
+import java.util.concurrent.ConcurrentHashMap;
+
+import com.sap.sailing.domain.common.Wind;
+import com.sap.sailing.domain.tracking.WindListener;
 import com.sap.sailing.nmeaconnector.NMEAWindReceiver;
 
 public class NMEAWindReceiverImpl implements NMEAWindReceiver {
+    private final ConcurrentHashMap<WindListener, WindListener> listeners;
+    
+    public NMEAWindReceiverImpl() {
+        super();
+        this.listeners = new ConcurrentHashMap<>();
+    }
 
+    @Override
+    public void addWindListener(WindListener listener) {
+        listeners.put(listener, listener);
+    }
+
+    @Override
+    public void removeWindListener(WindListener listener) {
+        listeners.remove(listener);
+    }
+
+    private void notifyListeners(Wind wind) {
+        for (WindListener listener : listeners.values()) {
+            listener.windDataReceived(wind);
+        }
+    }
 }