# HG changeset patch
# User Sascha L. Teichmann <sascha.teichmann@intevation.de>
# Date 1308307254 0
# Node ID b972eba2ed8ade2b30a63f6e4b38426455ab07e1
# Parent  708b270dfd3077bb5db11770d8b29aa9aa03f096
Removed ComputeCallback because this was thought too complicated. Fixed issue with facets not be re-generated if same state is entered again.

flys-artifacts/branches/facets-slt@2143 c6561f87-3c4e-4783-a992-168aeb5c3f6f

diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/FLYSArtifact.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/FLYSArtifact.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/FLYSArtifact.java	Fri Jun 17 10:40:54 2011 +0000
@@ -46,13 +46,12 @@
 
 import de.intevation.flys.artifacts.cache.CacheFactory;
 
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallback.ComputeType;
 import de.intevation.flys.artifacts.model.DischargeTables;
 import de.intevation.flys.artifacts.model.RiverFactory;
 import de.intevation.flys.artifacts.model.Segment;
 
 import de.intevation.flys.artifacts.states.DefaultState;
+import de.intevation.flys.artifacts.states.DefaultState.ComputeType;
 import de.intevation.flys.artifacts.states.LocationDistanceSelect;
 
 
@@ -1092,62 +1091,62 @@
 
         logger.debug("Create ComputeCallback for state: " + current.getID());
 
-        ComputeCallback callback = current.createComputeCallback(hash(), this);
-
-        if (callback == null) {
-            logger.info("There is no data which needs to be computed.");
-            return null;
-        }
-
-        return compute(context, hash, callback, type);
+        return compute(context, hash, current, type);
     }
 
 
     public Object compute(
-        CallContext     context,
-        String          key,
-        ComputeCallback callback,
-        ComputeType     type)
-    {
-        String stateId = getCurrentStateId();
-        List<Facet> fs = facets.get(stateId);
-        if (fs == null) {
-            fs = new ArrayList<Facet>();
-            facets.put(stateId, fs);
-        }
+        CallContext   context,
+        String        key,
+        DefaultState  state,
+        ComputeType   type
+    ) {
+        String stateID = state.getID();
 
-        Cache cache = CacheFactory.getCache(COMPUTING_CACHE);
-        if (cache == null) {
+        List<Facet> fs = new ArrayList<Facet>();
+
+        try {
+            Cache cache = CacheFactory.getCache(COMPUTING_CACHE);
+
+            Object old = null;
+
+            if (cache != null) {
+                net.sf.ehcache.Element element = cache.get(key);
+                if (element != null) {
+                    logger.debug("Got computation result from cache.");
+                    old = element.getValue();
+                }
+            }
+
+            Object res;
             switch (type) {
                 case FEED:
-                    return callback.computeFeed(context, fs);
+                    res = state.computeFeed(this, key, context, fs, old);
+                    break;
+                case ADVANCE:
+                    res = state.computeFeed(this, key, context, fs, old);
+                    break;
+                default:
+                    res = null;
+            }
 
-                case ADVANCE:
-                    return callback.computeAdvance(context, fs);
+            if (cache != null && old != res && res != null) {
+                logger.debug("Store computation result to cache.");
+                net.sf.ehcache.Element element =
+                    new net.sf.ehcache.Element(key, res);
+                cache.put(element);
+            }
+
+            return res;
+        }
+        finally {
+            if (fs.isEmpty()) {
+                facets.remove(stateID);
+            }
+            else {
+                facets.put(stateID, fs);
             }
         }
-
-        net.sf.ehcache.Element element = cache.get(key);
-        if (element != null) {
-            logger.debug("Got computation values from cache.");
-            return element.getValue();
-        }
-
-        Object result = null;
-        switch (type) {
-            case FEED:
-                result = callback.computeFeed(context, fs);
-                break;
-
-            case ADVANCE:
-                result = callback.computeAdvance(context, fs);
-        }
-
-        if (result != null) {
-            cache.put(new net.sf.ehcache.Element(key, result));
-        }
-
-        return result;
     }
 
 
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/ComputeCallback.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/ComputeCallback.java	Fri Jun 17 09:19:43 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,20 +0,0 @@
-package de.intevation.flys.artifacts.model;
-
-import java.util.List;
-
-import de.intevation.artifacts.CallContext;
-
-import de.intevation.artifactdatabase.state.Facet;
-
-
-public interface ComputeCallback {
-
-    public enum ComputeType {
-        FEED, ADVANCE
-    }
-
-    Object computeAdvance(CallContext context, List<Facet> facets);
-
-    Object computeFeed(CallContext context, List<Facet> facets);
-}
-// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/ComputeCallbackAdapter.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/ComputeCallbackAdapter.java	Fri Jun 17 09:19:43 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,23 +0,0 @@
-package de.intevation.flys.artifacts.model;
-
-import java.util.List;
-
-import de.intevation.artifacts.CallContext;
-
-import de.intevation.artifactdatabase.state.Facet;
-
-
-public class ComputeCallbackAdapter implements ComputeCallback {
-
-    @Override
-    public Object computeAdvance(CallContext context, List<Facet> facets) {
-        return null;
-    }
-
-
-    @Override
-    public Object computeFeed(CallContext context, List<Facet> facets) {
-        return null;
-    }
-}
-// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/DurationCurveFacet.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/DurationCurveFacet.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/DurationCurveFacet.java	Fri Jun 17 10:40:54 2011 +0000
@@ -8,7 +8,8 @@
 import de.intevation.artifactdatabase.state.DefaultFacet;
 
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback.ComputeType;
+
+import de.intevation.flys.artifacts.states.DefaultState.ComputeType;
 
 
 public class DurationCurveFacet extends DefaultFacet {
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java	Fri Jun 17 10:40:54 2011 +0000
@@ -8,8 +8,8 @@
 import de.intevation.artifactdatabase.state.DefaultFacet;
 
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback.ComputeType;
 
+import de.intevation.flys.artifacts.states.DefaultState.ComputeType;
 
 public class WaterlevelFacet extends DefaultFacet {
 
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/ComputedDischargeCurveState.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/ComputedDischargeCurveState.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/ComputedDischargeCurveState.java	Fri Jun 17 10:40:54 2011 +0000
@@ -10,8 +10,6 @@
 
 import de.intevation.flys.artifacts.FLYSArtifact;
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallbackAdapter;
 import de.intevation.flys.artifacts.model.FacetTypes;
 import de.intevation.flys.artifacts.model.WaterlevelFacet;
 import de.intevation.flys.artifacts.model.WQKms;
@@ -36,43 +34,45 @@
 
 
     @Override
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
-        final WINFOArtifact winfo = (WINFOArtifact) flys;
-
-        return new ComputeCallbackAdapter() {
-
-            @Override
-            public Object computeAdvance(
-                CallContext context,
-                List<Facet> facets)
-            {
-                WQKms res = winfo.getComputedDischargeCurveData();
+    public Object computeAdvance(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        WINFOArtifact winfo = (WINFOArtifact)artifact;
 
-                if (res == null) {
-                    logger.debug("No results given.");
-                    return null;
-                }
-
-                Object[] args = new Object[] {
-                    winfo.getRiver().getName(),
-                    res.getName()
-                };
+        WQKms res;
 
-                String name = Resources.getMsg(
-                    context.getMeta(),
-                    "chart.computed.discharge.curve.curve.label",
-                    "",
-                    args);
+        if (old instanceof WQKms []) {
+            res = ((WQKms [])old)[0];
+        }
+        else {
+            res = winfo.getComputedDischargeCurveData();
 
-                Facet q = new WaterlevelFacet(0, COMPUTED_DISCHARGE_Q, name);
+            if (res == null) {
+                logger.debug("No results given.");
+                return null;
+            }
+        }
 
-                facets.add(q);
+        Object[] args = new Object[] {
+            winfo.getRiver().getName(),
+            res.getName()
+        };
 
-                return new WQKms[] { res };
-            }
-        };
+        String name = Resources.getMsg(
+            context.getMeta(),
+            "chart.computed.discharge.curve.curve.label",
+            "",
+            args);
+
+        Facet q = new WaterlevelFacet(0, COMPUTED_DISCHARGE_Q, name);
+
+        facets.add(q);
+
+        return new WQKms[] { res };
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DefaultState.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DefaultState.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DefaultState.java	Fri Jun 17 10:40:54 2011 +0000
@@ -4,6 +4,7 @@
 import java.util.Iterator;
 import java.util.Locale;
 import java.util.Map;
+import java.util.List;
 
 import org.apache.log4j.Logger;
 
@@ -19,11 +20,14 @@
 import de.intevation.artifacts.common.utils.XMLUtils;
 
 import de.intevation.artifactdatabase.ProtocolUtils;
+
 import de.intevation.artifactdatabase.data.StateData;
+
 import de.intevation.artifactdatabase.state.AbstractState;
+import de.intevation.artifactdatabase.state.Facet;
 
 import de.intevation.flys.artifacts.FLYSArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
+
 import de.intevation.flys.artifacts.resources.Resources;
 
 
@@ -35,6 +39,9 @@
     /** The logger that is used in this class.*/
     private static Logger logger = Logger.getLogger(DefaultState.class);
 
+    public static enum ComputeType {
+        FEED, ADVANCE
+    }
 
     protected StateData getData(FLYSArtifact artifact,  String name) {
         return artifact.getData(name);
@@ -257,10 +264,23 @@
         return null;
     }
 
+    public Object computeAdvance(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context, 
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        return null;
+    }
 
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
+    public Object computeFeed(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
         return null;
     }
 }
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DischargeLongitudinalSection.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DischargeLongitudinalSection.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DischargeLongitudinalSection.java	Fri Jun 17 10:40:54 2011 +0000
@@ -10,8 +10,6 @@
 
 import de.intevation.flys.artifacts.FLYSArtifact;
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallbackAdapter;
 import de.intevation.flys.artifacts.model.FacetTypes;
 import de.intevation.flys.artifacts.model.WaterlevelFacet;
 import de.intevation.flys.artifacts.model.WQKms;
@@ -26,65 +24,66 @@
 
 
     @Override
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
-        final WINFOArtifact winfo = (WINFOArtifact) flys;
-
-        return new ComputeCallbackAdapter() {
-
-            @Override
-            public Object computeAdvance(
-                CallContext context,
-                List<Facet> facets)
-            {
-                WQKms res[] = winfo.getDischargeLongitudinalSectionData();
-
-                if (res == null) {
-                    logger.debug("No results given.");
-                    return null;
-                }
-
-                for (int i = 0; i < res.length; i++) {
-                    String nameW = null;
-                    String nameQ = null;
+    public Object computeAdvance(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        WQKms [] res;
 
-                    if (winfo.isQ()) {
-                        nameQ = res[i].getName();
-                        nameW = "W(" + nameQ + ")";
-                    }
-                    else {
-                        nameW = res[i].getName();
-                        nameQ = "Q(" + nameQ + ")";
-                    }
-
-                    Facet w = new WaterlevelFacet(
-                        i, DISCHARGE_LONGITUDINAL_W, nameW);
-
-                    Facet q = new WaterlevelFacet(
-                        i, DISCHARGE_LONGITUDINAL_Q, nameQ);
-
-                    facets.add(w);
-                    facets.add(q);
+        WINFOArtifact winfo = (WINFOArtifact)artifact;
 
-                    if (res[i] instanceof WQCKms) {
-                        // TODO DO i18n
-
-                        String nameC = nameW.replace(
-                            "Benutzerdefiniert",
-                            "Benutzerdefiniert [korrigiert]");
+        if (old instanceof WQCKms []) {
+            res = (WQCKms [])old;
+        }
+        else {
+            res = winfo.getDischargeLongitudinalSectionData();
 
-                        Facet c = new WaterlevelFacet(
-                            i, DISCHARGE_LONGITUDINAL_C, nameC);
+            if (res == null) {
+                logger.debug("No results given.");
+                return null;
+            }
+        }
 
-                        facets.add(c);
-                    }
-                }
+        for (int i = 0; i < res.length; i++) {
+            String nameW = null;
+            String nameQ = null;
 
-                return res;
+            if (winfo.isQ()) {
+                nameQ = res[i].getName();
+                nameW = "W(" + nameQ + ")";
             }
-        };
+            else {
+                nameW = res[i].getName();
+                nameQ = "Q(" + nameQ + ")";
+            }
 
+            Facet w = new WaterlevelFacet(
+                i, DISCHARGE_LONGITUDINAL_W, nameW);
+
+            Facet q = new WaterlevelFacet(
+                i, DISCHARGE_LONGITUDINAL_Q, nameQ);
+
+            facets.add(w);
+            facets.add(q);
+
+            if (res[i] instanceof WQCKms) {
+                // TODO DO i18n
+
+                String nameC = nameW.replace(
+                    "Benutzerdefiniert",
+                    "Benutzerdefiniert [korrigiert]");
+
+                Facet c = new WaterlevelFacet(
+                    i, DISCHARGE_LONGITUDINAL_C, nameC);
+
+                facets.add(c);
+            }
+        }
+
+        return res;
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DurationCurveState.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DurationCurveState.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/DurationCurveState.java	Fri Jun 17 10:40:54 2011 +0000
@@ -10,8 +10,6 @@
 
 import de.intevation.flys.artifacts.FLYSArtifact;
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallbackAdapter;
 import de.intevation.flys.artifacts.model.DurationCurveFacet;
 import de.intevation.flys.artifacts.model.FacetTypes;
 import de.intevation.flys.artifacts.model.WQDay;
@@ -35,50 +33,51 @@
 
 
     @Override
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
-        final WINFOArtifact winfo = (WINFOArtifact) flys;
-
-        return new ComputeCallbackAdapter() {
-
-            @Override
-            public Object computeAdvance(
-                CallContext context,
-                List<Facet> facets)
-            {
-                WQDay res = winfo.getDurationCurveData();
-
-                if (res == null) {
-                    logger.debug("No results given.");
-                    return null;
-                }
+    public Object computeAdvance(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        WINFOArtifact winfo = (WINFOArtifact)artifact;
 
-                Object[] args = new Object[] {
-                    winfo.getRiver().getName()
-                };
-
-                String nameW = Resources.getMsg(
-                    context.getMeta(),
-                    "chart.duration.curve.curve.w",
-                    "",
-                    args);
+        WQDay res;
 
-                String nameQ = Resources.getMsg(
-                    context.getMeta(),
-                    "chart.duration.curve.curve.q",
-                    "",
-                    args);
+        if (old instanceof WQDay []) {
+            res = ((WQDay [])old)[0];
+        }
+        else {
+            res = winfo.getDurationCurveData();
+            if (res == null) {
+                logger.debug("No results given.");
+                return null;
+            }
+        }
 
-                Facet w = new DurationCurveFacet(0, DURATION_W, nameW);
-                Facet q = new DurationCurveFacet(0, DURATION_Q, nameQ);
+        Object[] args = new Object[] {
+            winfo.getRiver().getName()
+        };
 
-                facets.add(w);
-                facets.add(q);
+        String nameW = Resources.getMsg(
+            context.getMeta(),
+            "chart.duration.curve.curve.w",
+            "",
+            args);
 
-                return new WQDay[] { res };
-            }
-        };
+        String nameQ = Resources.getMsg(
+            context.getMeta(),
+            "chart.duration.curve.curve.q",
+            "",
+            args);
+
+        Facet w = new DurationCurveFacet(0, DURATION_W, nameW);
+        Facet q = new DurationCurveFacet(0, DURATION_Q, nameQ);
+
+        facets.add(w);
+        facets.add(q);
+
+        return new WQDay[] { res };
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/LocationDistanceSelect.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/LocationDistanceSelect.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/LocationDistanceSelect.java	Fri Jun 17 10:40:54 2011 +0000
@@ -1,6 +1,7 @@
 package de.intevation.flys.artifacts.states;
 
 import java.util.List;
+import java.util.Map;
 
 import org.apache.log4j.Logger;
 
@@ -21,9 +22,9 @@
 
 import de.intevation.flys.artifacts.FLYSArtifact;
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallbackAdapter;
+
 import de.intevation.flys.artifacts.model.RiverFactory;
+
 import de.intevation.flys.artifacts.resources.Resources;
 
 /**
@@ -299,18 +300,28 @@
 
 
     @Override
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
-        final WINFOArtifact winfo = (WINFOArtifact) flys;
+    public Object computeFeed(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        WINFOArtifact winfo = (WINFOArtifact)artifact;
 
-        return new ComputeCallbackAdapter() {
+        Map<String, double [][]> res;
 
-            @Override
-            public Object computeFeed(CallContext context, List<Facet> facets) {
-                return winfo.getDischargeCurveData();
-            }
-        };
+        if (old instanceof Map<?, ?>) {
+            res = (Map<String, double [][]>)old;
+        }
+        else {
+            res = winfo.getDischargeCurveData();
+        }
+
+        // TODO: Generate facets!
+
+
+        return res;
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :
diff -r 708b270dfd30 -r b972eba2ed8a flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/WaterlevelState.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/WaterlevelState.java	Fri Jun 17 09:19:43 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/states/WaterlevelState.java	Fri Jun 17 10:40:54 2011 +0000
@@ -15,8 +15,6 @@
 
 import de.intevation.flys.artifacts.FLYSArtifact;
 import de.intevation.flys.artifacts.WINFOArtifact;
-import de.intevation.flys.artifacts.model.ComputeCallback;
-import de.intevation.flys.artifacts.model.ComputeCallbackAdapter;
 import de.intevation.flys.artifacts.model.FacetTypes;
 import de.intevation.flys.artifacts.model.WaterlevelFacet;
 import de.intevation.flys.artifacts.model.WQKms;
@@ -42,53 +40,52 @@
 
 
     @Override
-    public ComputeCallback createComputeCallback(
-        String hash, FLYSArtifact flys)
-    {
-        logger.debug("Create waterlevel ComputeCallback.");
-
-        final WINFOArtifact winfo = (WINFOArtifact) flys;
-
-        return new ComputeCallbackAdapter() {
-
-            @Override
-            public Object computeAdvance(
-                CallContext context,
-                List<Facet> facets)
-            {
-                WQKms[] res = winfo.getWaterlevelData();
-
-                if (res == null) {
-                    logger.debug("No results given.");
-                    return null;
-                }
+    public Object computeAdvance(
+        FLYSArtifact artifact,
+        String       hash,
+        CallContext  context,
+        List<Facet>  facets, 
+        Object       old
+    ) {
+        WINFOArtifact winfo = (WINFOArtifact)artifact;
 
-                for (int i = 0; i < res.length; i++) {
-                    String nameW = null;
-                    String nameQ = null;
-
-                    if (winfo.isQ()) {
-                        nameQ = res[i].getName();
-                        nameW = "W(" + nameQ + ")";
-                    }
-                    else {
-                        nameW = res[i].getName();
-                        nameQ = "Q(" + nameQ + ")";
-                    }
+        WQKms [] res;
 
-                    logger.debug("Create facet: " + nameW);
-                    logger.debug("Create facet: " + nameQ);
-
-                    Facet w = new WaterlevelFacet(i, LONGITUDINAL_W, nameW);
-                    Facet q = new WaterlevelFacet(i, LONGITUDINAL_Q, nameQ);
+        if (old instanceof WQKms []) {
+            res = (WQKms [])old;
+        }
+        else {
+            res = winfo.getWaterlevelData();
+            if (res == null) {
+                logger.debug("No results given.");
+                return null;
+            }
+        }
 
-                    facets.add(w);
-                    facets.add(q);
-                }
+        for (int i = 0; i < res.length; i++) {
+            String nameW = null;
+            String nameQ = null;
 
-                return res;
+            if (winfo.isQ()) {
+                nameQ = res[i].getName();
+                nameW = "W(" + nameQ + ")";
             }
-        };
+            else {
+                nameW = res[i].getName();
+                nameQ = "Q(" + nameQ + ")";
+            }
+
+            logger.debug("Create facet: " + nameW);
+            logger.debug("Create facet: " + nameQ);
+
+            Facet w = new WaterlevelFacet(i, LONGITUDINAL_W, nameW);
+            Facet q = new WaterlevelFacet(i, LONGITUDINAL_Q, nameQ);
+
+            facets.add(w);
+            facets.add(q);
+        }
+
+        return res;
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :