--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/Calculation.java	Fri Jun 10 10:10:04 2011 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/Calculation.java	Fri Jun 10 12:38:08 2011 +0000
@@ -6,10 +6,14 @@
 import java.util.List;
 import java.util.ArrayList;
 
+import java.io.Serializable;
+
 public class Calculation
+implements   Serializable
 {
-    public static class Problem {
-
+    public static class Problem 
+    implements          Serializable
+    {
         protected Double km;
         protected String msg;
 
@@ -59,6 +63,10 @@
         return problems != null && !problems.isEmpty();
     }
 
+    public int numProblems() {
+        return problems != null ? problems.size() : 0;
+    }
+
     public List<Problem> getProblems() {
         return problems;
     }