--- a/artifact-database/src/main/java/de/intevation/artifactdatabase/state/Facet.java	Wed Nov 23 17:17:39 2011 +0000
+++ b/artifact-database/src/main/java/de/intevation/artifactdatabase/state/Facet.java	Wed Nov 30 08:13:48 2011 +0000
@@ -1,5 +1,7 @@
 package de.intevation.artifactdatabase.state;
 
+import java.util.List;
+
 import java.io.Serializable;
 
 import org.w3c.dom.Document;
@@ -49,6 +51,32 @@
 
 
     /**
+     * Get keys for which this Facet can provide data (for other facets, not
+     * for plot).
+     *
+     * @return list of keys
+     */
+    List getDataProviderKeys();
+
+
+    /**
+     * Provide data to other facet.
+     *
+     * @param art  The artifact that this facet belongs to.
+     * @param key  the key of the requested service.
+     * @param prm  optional parameters.
+     * @param ctxt the callcontext.
+     *
+     * @return the data
+     */
+    Object provideBlackboardData(
+        Artifact art,
+        Object key,
+        Object prm,
+        CallContext ctxt);
+
+
+    /**
      * Write the internal representation of a facet to a node.
      *
      * @param doc A Document.