diff --git a/xCAT-server/lib/xcat/monitoring/samples/mycode.pm b/xCAT-server/lib/xcat/monitoring/samples/mycode.pm
index 26f346060..2625f3120 100644
--- a/xCAT-server/lib/xcat/monitoring/samples/mycode.pm
+++ b/xCAT-server/lib/xcat/monitoring/samples/mycode.pm
@@ -2,26 +2,51 @@
 package xCAT_monitoring::mycode;
 1;
 
-# This subroutine get called when new nodes are added into the cluster
-# or nodes are removed from the cluster.
-#
+#--------------------------------------------------------------------------------
+=head3   processTableChanges
+  This subroutine get called when new nodes are added into the cluster
+   or nodes are removed from the cluster, or a row is modified.
+    Arguments:
+      action - table action. It can be d for rows deleted, a for rows added
+                    or u for rows updated.
+      tablename - string. The name of the DB table whose data has been changed.
+      old_data - an array reference of the old row data that has been changed.
+           The first element is an array reference that contains the column names.
+           The rest of the elelments are also array references each contains
+           attribute values of a row.
+           It is set when the action is u or d.
+      new_data - a hash refernce of new row data; only changed values are present
+           in the hash.  It is keyed by column names.
+           It is set when the action is u or a.
+    Returns:
+      0
+    Comment:
+       To test, 
+        1. copy this file to /opt/xcat/lib/perl/xCAT_monitoring directory.
+        2. run regnotif /opt/xcat/lib/perl/xCAT_monitoring/mycode.pm nodelist -o a,u,d
+        3. Then change the nodelist table (add node, remove node, or change status column).
+        4. Watch /var/log/mycode.log for output.
+=cut
+#-------------------------------------------------------------------------------
 sub processTableChanges {
   my $action=shift;
   if ($action =~ /xCAT_monitoring::mycode/){
     $action=shift;
   }
+
   my $tablename=shift;
   my $old_data=shift;
   my $new_data=shift;
 
   my @nodenames=();
+  open(FILE, ">>/var/log/mycode.log") or dir ("cannot open the file\n");
+  ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime(time);
+  printf FILE "\n-----------%2d-%02d-%04d %02d:%02d:%02d-----------\n", $mon+1,$mday,$year+1900,$hour,$min,$sec;  
   if ($action eq "a") { #nodes added in the cluster
     if ($new_data) {
       push(@nodenames, $new_data->{node});
       $noderange=join(',', @nodenames);
-      open(FILE, ">>/var/log/mycode.log") or dir ("cannot open the file\n");
       print (FILE "new nodes in the cluster are: $noderange\n"); 
-      close(FILE);
     }
   }
   elsif ($action eq "d") { #nodes removed from the cluster
@@ -39,11 +64,30 @@ sub processTableChanges {
 
       if (@nodenames > 0) {
          $noderange=join(',', @nodenames);
-         open(FILE, ">>/var/log/mycode.log") or dir ("cannot open the file\n");
          print (FILE "nodes leaving the cluster are: $noderange\n");
-         close(FILE);
+      }
+    }
+  } else { #update case, assuminmg monitoring nodelist.status
+    $newstatus;
+    if ($new_data) {
+      $newstatus=$new_data->{status};
+    }
+    if ($old_data->[0]) {
+      $colnames=$old_data->[0];
+      my $m;
+      my $k;
+      for ($i=0; $i<@$colnames; ++$i) {
+        if ($colnames->[$i] eq "node") {$m=$i}
+        if ($colnames->[$i] eq "status") {$k=$i; }
+      }
+
+      for (my $j=1; $j<@$old_data; ++$j) {
+        print FILE "node=". $old_data->[$j]->[$m] . " ,";
+        print FILE "old_status=". $old_data->[$j]->[$k] . " ,";
+        print FILE "new_status=$newstatus\n";
       }
     }
   }
+  close(FILE);
   return 0;
 }