--- a/flys-artifacts/ChangeLog	Tue Apr 19 12:31:07 2011 +0000
+++ b/flys-artifacts/ChangeLog	Tue Apr 19 12:33:39 2011 +0000
@@ -1,3 +1,11 @@
+2011-04-19  Ingo Weinzierl <ingo@intevation.de>
+
+	* src/main/java/de/intevation/flys/artifacts/services/MainValuesService.java:
+	  New. This service returns an XML document that includes the main values
+	  of a gauge based on a river name, a start and an end point.
+
+	* doc/conf/conf.xml: Registered the MainValuesService.
+
 2011-04-19  Ingo Weinzierl <ingo@intevation.de>
 
 	* src/main/java/de/intevation/flys/artifacts/model/MainValuesFactory.java:

--- a/flys-artifacts/doc/conf/conf.xml	Tue Apr 19 12:31:07 2011 +0000
+++ b/flys-artifacts/doc/conf/conf.xml	Tue Apr 19 12:33:39 2011 +0000
@@ -28,6 +28,10 @@
                 name="distanceinfo"
                 service="de.intevation.flys.artifacts.services.DistanceInfoService"
                 description="Returns a list of distances supported by a specific river.">de.intevation.artifactdatabase.DefaultServiceFactory</service-factory>
+            <service-factory
+                name="mainvalues"
+                service="de.intevation.flys.artifacts.services.MainValuesService"
+                description="Returns the main values of a river's gauge based on a start and end point of the river.">de.intevation.artifactdatabase.DefaultServiceFactory</service-factory>
         </service-factories>
 
     </factories>

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/services/MainValuesService.java	Tue Apr 19 12:33:39 2011 +0000
@@ -0,0 +1,316 @@
+package de.intevation.flys.artifacts.services;
+
+import java.util.List;
+
+import org.apache.log4j.Logger;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+
+import org.hibernate.Session;
+
+import de.intevation.artifacts.CallMeta;
+
+import de.intevation.artifactdatabase.DefaultService;
+
+import de.intevation.artifacts.common.ArtifactNamespaceContext;
+import de.intevation.artifacts.common.utils.XMLUtils;
+import de.intevation.artifacts.common.utils.XMLUtils.ElementCreator;
+
+import de.intevation.flys.backend.SessionHolder;
+import de.intevation.flys.model.Gauge;
+import de.intevation.flys.model.MainValue;
+import de.intevation.flys.model.MainValueType;
+import de.intevation.flys.model.NamedMainValue;
+import de.intevation.flys.model.Range;
+import de.intevation.flys.model.River;
+
+import de.intevation.flys.artifacts.model.MainValuesFactory;
+import de.intevation.flys.artifacts.model.RiverFactory;
+
+
+/**
+ * This service returns the main values of a river's gauge based on the start
+ * and end point of the river.
+ *
+ * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
+ */
+public class MainValuesService extends DefaultService {
+
+    /** The logger that is used by this service.*/
+    private static Logger logger = Logger.getLogger(MainValuesService.class);
+
+
+    /** The XPath that points to the river definition of the incoming request.*/
+    public static final String XPATH_RIVER = "/art:mainvalues/art:river/text()";
+
+    /** The XPath that points to the start definition of the incoming request.*/
+    public static final String XPATH_START = "/art:mainvalues/art:end/text()";
+
+    /** The XPath that points to the end definition of the incoming request.*/
+    public static final String XPATH_END = "/art:mainvalues/art:start/text()";
+
+    /**
+     * The default constructor.
+     */
+    public MainValuesService() {
+    }
+
+
+    public Document process(
+        Document data,
+        Object   context,
+        CallMeta callMeta)
+    {
+        logger.debug("MainValuesService.process");
+
+        try {
+            River river     = getRequestedRiver(data);
+            double[] minmax = getRequestedStartEnd(data, river);
+            Gauge gauge     = river.determineGauge(minmax[0], minmax[1]);
+
+            List<MainValue> mainValues = getMainValues(river, gauge);
+
+            return buildDocument(river, gauge, mainValues, context);
+        }
+        catch (NullPointerException npe) {
+            logger.error("Could not process the request.");
+            logger.error(npe, npe);
+
+            return XMLUtils.newDocument();
+        }
+    }
+
+
+    /**
+     * This method extracts the river from the incoming request. If no river
+     * string was found or no river is found in the database based on this
+     * string a NullPointerException is thrown.
+     *
+     * @param data The incoming request data.
+     *
+     * @return the River object.
+     */
+    protected River getRequestedRiver(Document data)
+    throws    NullPointerException
+    {
+        logger.debug("MainValuesService.getRiver");
+
+        String riverStr = XMLUtils.xpathString(
+            data, XPATH_RIVER, ArtifactNamespaceContext.INSTANCE);
+
+        if (riverStr == null || riverStr.trim().length() == 0) {
+            throw new NullPointerException("No river found in the request.");
+        }
+
+        River river = RiverFactory.getRiver(riverStr);
+
+        if (river == null) {
+            throw new NullPointerException("No such river found: " + riverStr);
+        }
+
+        return river;
+    }
+
+
+    /**
+     * This method extracts the start and end point from incoming request
+     * document and returns both values in an array. If no start and end strings
+     * are found in the document, the min/max values of the <i>river</i> are
+     * returned.
+     *
+     * @param data The incoming request data.
+     * @param river The river of the request.
+     *
+     * @return the start and end point.
+     */
+    protected double[] getRequestedStartEnd(Document data, River river) {
+        logger.debug("MainValuesService.getStartEnd");
+
+        String startStr = XMLUtils.xpathString(
+            data, XPATH_START, ArtifactNamespaceContext.INSTANCE);
+
+        String endStr = XMLUtils.xpathString(
+            data, XPATH_END, ArtifactNamespaceContext.INSTANCE);
+
+        try {
+            double start = Double.parseDouble(startStr);
+            double end   = Double.parseDouble(endStr);
+
+            logger.debug("Found start: " + start);
+            logger.debug("Found end: " + end);
+
+            return new double[] { start, end };
+        }
+        catch (NumberFormatException nfe) {
+            logger.warn(nfe, nfe);
+
+            return river.determineMinMaxDistance();
+        }
+    }
+
+
+    /**
+     * This method creates the result document that includes the main values of
+     * the specified <i>gauge</i>.
+     *
+     * @param river The river.
+     * @param gauge The gauge.
+     *
+     * @return a document that includes the main values of the specified river
+     * at the specified gauge.
+     */
+    protected List<MainValue> getMainValues(River river, Gauge gauge)
+    throws    NullPointerException
+    {
+        if (logger.isDebugEnabled()) {
+            logger.debug("MainValuesService.buildMainValues");
+            logger.debug("River: " + river.getName());
+            logger.debug("Gauge: " + gauge.getName());
+        }
+
+        Session session = SessionHolder.acquire();
+        try {
+            List<MainValue> mainValues = MainValuesFactory.getMainValues(gauge);
+
+            if (mainValues == null || mainValues.isEmpty()) {
+                throw new NullPointerException("No main values found.");
+            }
+
+            logger.debug(mainValues.size() + " main values found.");
+
+            return mainValues;
+        }
+        finally {
+            session.close();
+            SessionHolder.release();
+        }
+    }
+
+
+    protected Document buildDocument(
+        River           river,
+        Gauge           gauge,
+        List<MainValue> mainValues,
+        Object          context)
+    {
+        logger.debug("MainValuesService.buildDocument");
+
+        Document doc = XMLUtils.newDocument();
+
+        ElementCreator cr = new ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        Element rootEl = cr.create("service");
+        cr.addAttr(rootEl, "name", "mainvalues");
+
+        doc.appendChild(rootEl);
+
+        appendMetaInformation(doc, rootEl, river, gauge, context);
+        appendMainValues(doc, rootEl, mainValues, context);
+
+        return doc;
+    }
+
+
+    /**
+     * This method appends some meta information to the result document.
+     * Currently, the river's and gauge's names and the gauge's range are
+     * appended.
+     *
+     * @param root The root element of the result document.
+     * @param river The river.
+     * @param gauge The gauge.
+     * @param context The context object.
+     */
+    protected void appendMetaInformation(
+        Document doc,
+        Element  root,
+        River    river,
+        Gauge    gauge,
+        Object   context)
+    {
+        logger.debug("MainValuesService.appendMetaInformation");
+
+        ElementCreator cr = new ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        Range range = gauge.getRange();
+
+        Element riverEl = cr.create("river");
+        cr.addAttr(riverEl, "name", river.getName());
+
+        Element gaugeEl = cr.create("gauge");
+        cr.addAttr(gaugeEl, "name", gauge.getName());
+        cr.addAttr(gaugeEl, "from", range.getA().toString());
+        cr.addAttr(gaugeEl, "to", range.getB().toString());
+
+        root.appendChild(riverEl);
+        root.appendChild(gaugeEl);
+    }
+
+
+    protected void appendMainValues(
+        Document        doc,
+        Element         root,
+        List<MainValue> mainValues,
+        Object          context)
+    {
+        logger.debug("MainValuesService.appendMainValues");
+
+        ElementCreator cr = new ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        Element list = cr.create("mainvalues");
+
+        for (MainValue mainValue: mainValues) {
+            Element newEl = buildMainValueElement(doc, mainValue, context);
+
+            if (newEl != null) {
+                list.appendChild(newEl);
+            }
+        }
+
+        root.appendChild(list);
+    }
+
+
+    /**
+     * This method builds a concrete mainvalue element. This element consists of
+     * three attributes: the value, its name and its type.
+     *
+     * @param doc The owner document.
+     * @param mainValue The mainvalue.
+     * @param context The context object.
+     *
+     * @return a mainvalue element.
+     */
+    protected Element buildMainValueElement(
+        Document  doc,
+        MainValue mainValue,
+        Object    context)
+    {
+        ElementCreator cr = new ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        NamedMainValue namedMainValue = mainValue.getMainValue();
+        MainValueType  mainValueType  = namedMainValue.getType();
+
+        Element el = cr.create("mainvalue");
+
+        cr.addAttr(el, "value", mainValue.getValue().toString());
+        cr.addAttr(el, "name", namedMainValue.getName());
+        cr.addAttr(el, "type", mainValueType.getName());
+
+        return el;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :