--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/states/WQFixing.java	Wed May 22 18:10:48 2013 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/states/WQFixing.java	Wed May 22 18:32:51 2013 +0200
@@ -8,6 +8,8 @@
 package org.dive4elements.river.artifacts.states;
 
 import org.dive4elements.artifacts.Artifact;
+import org.dive4elements.river.artifacts.D4EArtifact;
+import org.dive4elements.river.artifacts.model.RangeWithValues;
 
 import org.apache.log4j.Logger;
 
@@ -20,13 +22,28 @@
     /** The logger used in this state.*/
     private static Logger logger = Logger.getLogger(WQFixing.class);
 
+    /** Simple sanity check if values are positive numbers **/
     @Override
     public boolean validate(Artifact artifact)
     throws IllegalArgumentException
     {
         logger.debug("WQFixing.validate");
-        // A check for positive values is already done by the client
-        // all positive values are valid
+
+        RangeWithValues[] rwvs = extractInput(getData((D4EArtifact) artifact, "wq_values"));
+
+        if (rwvs == null) {
+            throw new IllegalArgumentException("error_missing_wq_data");
+        }
+
+        for (RangeWithValues rwv: rwvs) {
+            double[] values = rwv.getValues();
+            for (double val: values) {
+                if (val <= 0) {
+                    throw new IllegalArgumentException("error_validate_positive");
+                }
+            }
+        }
+
         return true;
     }