--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/model/Calculation.java	Wed Jun 26 13:26:43 2013 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/model/Calculation.java	Wed Jun 26 13:33:15 2013 +0200
@@ -78,6 +78,21 @@
         }
 
         @Override
+        public String toString() {
+            StringBuilder sb = new StringBuilder("problem: ");
+            if (km != null) {
+                sb.append("km: ").append(km).append(' ');
+            }
+            sb.append(msg);
+            if (args != null) {
+                for (Object arg: args) {
+                    sb.append(' ').append(arg);
+                }
+            }
+            return sb.toString();
+        }
+
+        @Override
         public boolean equals(Object other) {
             if (!(other instanceof Problem)) {
                 return false;
@@ -159,6 +174,18 @@
         return problems;
     }
 
+    public String problemsToString() {
+        StringBuilder sb = new StringBuilder("[");
+        for (int i = 0, N = problems.size(); i < N; ++i) {
+            if (i > 0) {
+                sb.append(", ");
+            }
+            sb.append(problems.get(i));
+        }
+        sb.append(']');
+        return sb.toString();
+    }
+
     public void toXML(Document document, CallMeta meta) {
 
         Element root = document.createElement("problems");