diff --git a/update-berths.pl b/update-berths.pl
index 931aec2..d35cc5b 100755
--- a/update-berths.pl
+++ b/update-berths.pl
@@ -7,6 +7,9 @@ use Net::MQTT::Simple;
 use JSON;
 use Data::Dumper;
 
+$| = 1 if $ENV{DEBUG};
+my $mqtt;
+
 sub assert($;$) {
     my ($required, $message) = @_;
     unless ($required) {
@@ -36,17 +39,67 @@ sub handle($$) {
     };
 
     if ($data) {
-        _debug( Dumper($data) );
+        # _debug( "[$topic] " . summary($data) );
+        foreach (@{$data}) {
+            process_message($_);
+        }
     } else {
         _error("Got invalid JSON data from $topic: $json");
     }
 }
 
+sub summary($) {
+    my $json = shift;
+    my $str = sprintf("Data blob containing %d messages", scalar @{$json});
+    return $str;
+}
+
+sub process_message($) {
+    # CA => "Step",
+    # CB => "Cancel",
+    # CC => "Interpose",
+    # CT => "Heartbeat",
+    my $msg = shift;
+    my $type = (keys %$msg)[0];
+    my %inner = %{$msg->{$type}};
+    if($type eq "CA_MSG") {
+        clear_berth($inner{area_id}, $inner{from});
+        set_berth($inner{area_id}, $inner{to}, $inner{descr});
+
+        # "STEP: $inner{area_id} $inner{to} := $inner{descr} at $inner{time}\n";
+    } elsif($type eq 'CB_MSG') {
+        clear_berth($inner{area_id}, $inner{from});
+        # "CLEAR: $inner{area_id} $inner{from} at $inner{time}\n";
+    } elsif($type eq 'CC_MSG') {
+        set_berth($inner{area_id}, $inner{to}, $inner{descr});
+        # "INTERPOSE: $inner{area_id} $inner{to} := $inner{descr} at $inner{time}\n";
+    } else {
+        # print "SKIPPING MESSAGE\n";
+    }
+}
+
+sub set_berth($$$) {
+    my ($area, $berth, $occupant) = @_;
+    publish("berths/$area/$berth", $occupant);
+}
+
+sub clear_berth($$) {
+    my ($area, $berth) = @_;
+    publish(sprintf("berths/%s/%s", $area||"-", $berth || "-"), "-");
+}
+
+sub publish($$) {
+    my ($topic, $message) = @_;
+    # _debug("$ENV{MQTT_PUBLISH_BASE}/$topic <-- $message");
+    $mqtt->retain("$ENV{MQTT_PUBLISH_BASE}/$topic", $message);
+}
+
 ### Check required environement variables are present
 foreach (
     qw(
         MQTT_SERVER
         MQTT_MONITOR
+        MQTT_PUBLISH_BASE
     )
 ) {
     assert($ENV{$_}, "`$_' not available");
@@ -54,7 +107,7 @@ foreach (
 
 ## Connect to MQTT
 _debug("Connecting to mqtt://$ENV{MQTT_SERVER}/$ENV{MQTT_MONITOR}");
-my $mqtt = Net::MQTT::Simple->new($ENV{MQTT_SERVER}) or die "Failed to connect to mqtt://$ENV{MQTT_SERVER}";
+$mqtt = Net::MQTT::Simple->new($ENV{MQTT_SERVER}) or die "Failed to connect to mqtt://$ENV{MQTT_SERVER}";
 
 $mqtt->subscribe(
     "$ENV{MQTT_MONITOR}" => sub {