started an NMEA wind receiver implementation by adding some Javadoc

Change-Id: I81ad85ef64bf34cfb38772f69e9a535bee3c6bec

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

@@ -0,0 +1,45 @@
+package com.sap.sailing.nmeaconnector;
+
+import net.sf.marineapi.nmea.event.SentenceListener;
+import net.sf.marineapi.nmea.io.SentenceReader;
+import net.sf.marineapi.nmea.sentence.DateSentence;
+import net.sf.marineapi.nmea.sentence.MWVSentence;
+import net.sf.marineapi.nmea.sentence.SentenceId;
+import net.sf.marineapi.nmea.sentence.TimeSentence;
+
+/**
+ * A stateful receiver that consumes sentences from an NMEA {@link SentenceReader}
+ * 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>
+ * 
+ * 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,
+ * it is not entirely clear in all cases if those angles have the magnetic declination
+ * already corrected. Only with {@link SentenceId#MWD} sentences does this become clear,
+ * and a value for the magnetic declination could be inferred. For now, we will assume
+ * that {@link SentenceId#MWV} values really provide angles based on true north if
+ * {@link MWVSentence#isTrue()} is {@code true}.<p>
+ * 
+ * This receiver assumes that the sentences do not necessarily have to be entirely
+ * time-synchronous. But different sentence types can provide "hints" as to the timing.
+ * GPS fixes (@link SentenceId#GGA} and other position fixes {@link SentenceId#GLL} have
+ * time of day but no date information. Other messages such as {@link SentenceId#RMC} and
+ * {@link SentenceId#ZDA} contain date and optionally time zone information. When analyzing
+ * the entire sequence, under certain assumptions such as fixes with time information being
+ * less than 24h apart from each other and with at least one {@link DateSentence} per day
+ * it is possible to combine {@link TimeSentence}s with the last date information into
+ * a full {@link TimePoint}.<p>
+ * 
+ * In order to also work in streaming mode and to provide {@link Wind} fixes as soon as
+ * all data relevant for a wind fix has been received, this receiver won't wait for the
+ * next timing information to interpolate, but instead the last timing data received
+ * before the wind measurement will be used for the {@link Wind} fix.
+ * 
+ * @author Axel Uhl (d043530)
+ *
+ */
+public interface NMEAWindReceiver {
+
+}

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

@@ -1,10 +1,13 @@
 package com.sap.sailing.nmeaconnector;
 
-import java.io.Reader;
+import java.io.InputStream;
 
 import com.sap.sailing.domain.common.Wind;
 import com.sap.sailing.nmeaconnector.impl.NmeaFactoryImpl;
 
+import net.sf.marineapi.nmea.sentence.MWVSentence;
+import net.sf.marineapi.nmea.sentence.ZDASentence;
+
 public interface NmeaFactory {
     static NmeaFactory INSTANCE = new NmeaFactoryImpl();
     
@@ -19,11 +22,11 @@ public interface NmeaFactory {
      * is relative to "true north" which we can only believe; it means that the instrument needs to have an understanding
      * of the magnetic declination at the time and position of the measurement.
      * 
-     * @param reader
+     * @param inputStream
      *            will be consumed up to its end but will not be closed; the caller remains responsible for closing the
-     *            reader.
+     *            input stream.
      * @return a sequence of {@link Wind} objects as extracted from the NMEA 0183 sentences found in the contents of the
      *         {@code reader}; never {@code null}, but possibly empty
      */
-    Iterable<Wind> readWind(Reader reader);
+    Iterable<Wind> readWind(InputStream inputStream);
 }

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

@@ -0,0 +1,7 @@
+package com.sap.sailing.nmeaconnector.impl;
+
+import com.sap.sailing.nmeaconnector.NMEAWindReceiver;
+
+public class NMEAWindReceiverImpl implements NMEAWindReceiver {
+
+}

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

@@ -1,6 +1,6 @@
 package com.sap.sailing.nmeaconnector.impl;
 
-import java.io.Reader;
+import java.io.InputStream;
 
 import com.sap.sailing.domain.common.Wind;
 import com.sap.sailing.nmeaconnector.NmeaFactory;
@@ -14,7 +14,7 @@ public class NmeaFactoryImpl implements NmeaFactory {
     }
 
     @Override
-    public Iterable<Wind> readWind(Reader reader) {
+    public Iterable<Wind> readWind(InputStream inputStream) {
         // TODO Auto-generated method stub
         return null;
     }