diff --git a/bin/start_hivemq b/bin/start_hivemq
index da24080b0f..535be780f0 100755
--- a/bin/start_hivemq
+++ b/bin/start_hivemq
@@ -1,3 +1,5 @@
 #!/bin/bash -e
 
+sudo systemctl stop mosquitto || true
+
 docker run -p 1883:1883 hivemq/hivemq-ce
diff --git a/udmis/etc/prod_pod.json b/udmis/etc/prod_pod.json
index 5a4b91da85..d2ea4e89d6 100644
--- a/udmis/etc/prod_pod.json
+++ b/udmis/etc/prod_pod.json
@@ -13,6 +13,7 @@
   },
   "crons": {
     "reglist": {
+      "periodic_sec": 10,
       "payload": "query/cloud:{}",
       "send_id": "${UDMI_PREFIX}udmi_control"
     }
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/core/ControlProcessor.java b/udmis/src/main/java/com/google/bos/udmi/service/core/ControlProcessor.java
index db395bca5f..d715ebc2b2 100644
--- a/udmis/src/main/java/com/google/bos/udmi/service/core/ControlProcessor.java
+++ b/udmis/src/main/java/com/google/bos/udmi/service/core/ControlProcessor.java
@@ -1,5 +1,6 @@
 package com.google.bos.udmi.service.core;
 
+import static com.google.udmi.util.JsonUtil.stringifyTerse;
 import static java.lang.String.format;
 
 import java.util.Objects;
@@ -18,4 +19,10 @@ public ControlProcessor(EndpointConfiguration config) {
   private static String makeTransactionId() {
     return format("CP:%08x", Objects.hash(System.currentTimeMillis(), Thread.currentThread()));
   }
+
+  @Override
+  protected void defaultHandler(Object message) {
+    debug("Received defaulted control message type %s: %s", message.getClass().getSimpleName(),
+        stringifyTerse(message));
+  }
 }
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/core/CronJob.java b/udmis/src/main/java/com/google/bos/udmi/service/core/CronJob.java
deleted file mode 100644
index a6becfd15b..0000000000
--- a/udmis/src/main/java/com/google/bos/udmi/service/core/CronJob.java
+++ /dev/null
@@ -1,69 +0,0 @@
-package com.google.bos.udmi.service.core;
-
-import static com.google.udmi.util.GeneralUtils.ifTrueGet;
-import static com.google.udmi.util.JsonUtil.fromStringStrict;
-import static com.google.udmi.util.JsonUtil.stringifyTerse;
-
-import com.google.bos.udmi.service.messaging.impl.MessageDispatcherImpl;
-import com.google.bos.udmi.service.pod.ContainerProvider;
-import udmi.schema.EndpointConfiguration;
-import udmi.schema.Envelope;
-import udmi.schema.Envelope.SubFolder;
-import udmi.schema.Envelope.SubType;
-
-/**
- * Simple clas to manage a distributed cron execution environment.
- */
-public class CronJob extends ProcessorBase {
-
-  private static final String SELF_ID = "groot";
-  private final Envelope envelope;
-  private final Object message;
-
-  /**
-   * Create an instance with the given config.
-   */
-  public CronJob(EndpointConfiguration config) {
-    super(config);
-
-    distributorName = config.distributor;
-
-    String[] targetMessage = config.payload.split(":", 2);
-
-    String[] parts = targetMessage[0].split("/");
-    envelope = new Envelope();
-    envelope.subType = SubType.fromValue(parts[0]);
-    envelope.subFolder = SubFolder.fromValue(parts[1]);
-    envelope.deviceRegistryId = ifTrueGet(parts.length >= 3, () -> parts[3]);
-    envelope.deviceId = ifTrueGet(parts.length >= 4, () -> parts[4]);
-    envelope.gatewayId = SELF_ID + DistributorPipe.ROUTE_SEPERATOR + config.name;
-
-    Class<?> messageClass = MessageDispatcherImpl.getMessageClassFor(envelope, false);
-    String payload = ifTrueGet(targetMessage.length > 1, () -> targetMessage[1], EMPTY_JSON);
-    message = fromStringStrict(messageClass, payload);
-
-    info("Set-up cron job for %s %s/%s to %s/%s", containerId, envelope.subType, envelope.subFolder,
-        envelope.deviceRegistryId, envelope.deviceId);
-  }
-
-  public static ContainerProvider from(EndpointConfiguration config) {
-    return new CronJob(config);
-  }
-
-  @Override
-  protected void periodicTask() {
-    info("Distributing %s %s/%s to %s/%s", containerId, envelope.subType, envelope.subFolder,
-        envelope.deviceRegistryId, envelope.deviceId);
-    distributor.publish(envelope, message, containerId);
-    handleTick(envelope, message);
-  }
-
-  @Override
-  protected void defaultHandler(Object message) {
-    handleTick(getContinuation(message).getEnvelope(), message);
-  }
-
-  private void handleTick(Envelope envelope, Object message) {
-    debug("Cron Job update " + stringifyTerse(envelope) + " " + stringifyTerse(message));
-  }
-}
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/core/CronProcessor.java b/udmis/src/main/java/com/google/bos/udmi/service/core/CronProcessor.java
new file mode 100644
index 0000000000..ae1e94ffbc
--- /dev/null
+++ b/udmis/src/main/java/com/google/bos/udmi/service/core/CronProcessor.java
@@ -0,0 +1,113 @@
+package com.google.bos.udmi.service.core;
+
+import static com.google.udmi.util.GeneralUtils.CSV_JOINER;
+import static com.google.udmi.util.GeneralUtils.ifTrueGet;
+import static com.google.udmi.util.GeneralUtils.ifTrueThen;
+import static com.google.udmi.util.JsonUtil.fromStringStrict;
+import static com.google.udmi.util.JsonUtil.isoConvert;
+import static com.google.udmi.util.JsonUtil.stringifyTerse;
+
+import com.google.bos.udmi.service.messaging.impl.MessageDispatcherImpl;
+import com.google.udmi.util.JsonUtil;
+import java.time.Duration;
+import java.util.Date;
+import java.util.SortedMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.atomic.AtomicReference;
+import udmi.schema.EndpointConfiguration;
+import udmi.schema.Envelope;
+import udmi.schema.Envelope.SubFolder;
+import udmi.schema.Envelope.SubType;
+
+/**
+ * Simple clas to manage a distributed cron execution environment.
+ */
+public class CronProcessor extends ProcessorBase {
+
+  public static final String PAYLOAD_SEPARATOR = ":";
+  public static final String PATH_SEPARATOR = "/";
+  private final Envelope srcEnvelope;
+  private final Object message;
+  private final SortedMap<String, Date> received = new ConcurrentSkipListMap<>();
+  private final Duration waitAndListen;
+  private final AtomicReference<Date> previousTick = new AtomicReference<>();
+
+  /**
+   * Create an instance with the given config.
+   */
+  public CronProcessor(EndpointConfiguration config) {
+    super(config);
+
+    distributorName = config.distributor;
+    waitAndListen = Duration.ofSeconds(periodicSec / 2);
+
+    String[] targetMessage = config.payload.split(PAYLOAD_SEPARATOR, 2);
+
+    String[] parts = targetMessage[0].split(PATH_SEPARATOR, 4);
+    srcEnvelope = new Envelope();
+    srcEnvelope.subType = SubType.fromValue(parts[0]);
+    srcEnvelope.subFolder = SubFolder.fromValue(parts[1]);
+    srcEnvelope.deviceRegistryId = ifTrueGet(parts.length >= 3, () -> parts[3]);
+    srcEnvelope.deviceId = ifTrueGet(parts.length >= 4, () -> parts[4]);
+
+    Class<?> messageClass = MessageDispatcherImpl.getMessageClassFor(srcEnvelope, false);
+    String payload = ifTrueGet(targetMessage.length > 1, () -> targetMessage[1], EMPTY_JSON);
+    message = fromStringStrict(messageClass, payload);
+  }
+
+  @Override
+  protected void defaultHandler(Object message) {
+    trackPod(getContinuation(message).getEnvelope());
+  }
+
+  @Override
+  protected void periodicTask() {
+    info("Distributing %s %s/%s to %s/%s", containerId, srcEnvelope.subType, srcEnvelope.subFolder,
+        srcEnvelope.deviceRegistryId, srcEnvelope.deviceId);
+
+    Date publishTime = new Date();
+    srcEnvelope.publishTime = publishTime;
+
+    distributor.publish(srcEnvelope, message, containerId);
+
+    trackPod(srcEnvelope);
+
+    Date before = previousTick.getAndSet(publishTime);
+
+    // Wait for half the window, to make sure everybody has a chance to report in.
+    scheduleIn(waitAndListen, () -> ifTrueThen(isAmGroot(before), this::processGroot));
+  }
+
+  private boolean isAmGroot(Date cutoffTime) {
+    debug("Check grootness for %s after %s", srcEnvelope.gatewayId, isoConvert(cutoffTime));
+
+    if (cutoffTime == null) {
+      return false;
+    }
+
+    debug("Received values: " + received.size() + " " + CSV_JOINER.join(
+        received.values().stream().map(JsonUtil::isoConvert).toList()));
+    received.entrySet().removeIf(entry -> entry.getValue().before(cutoffTime));
+    debug("Received %s is groot: %s", received.firstKey(), CSV_JOINER.join(received.keySet()));
+    return srcEnvelope.gatewayId.equals(received.firstKey());
+  }
+
+  private void processGroot() {
+    debug("Publishing as %s: %s", stringifyTerse(srcEnvelope), stringifyTerse(message));
+    publish(srcEnvelope, message);
+  }
+
+  private void trackPod(Envelope envelope) {
+    debug("Pod timestamp update %s to %s", envelope.gatewayId, isoConvert(envelope.publishTime));
+    received.put(envelope.gatewayId, envelope.publishTime);
+    debug("Received values: " + received.size() + " " + CSV_JOINER.join(
+        received.values().stream().map(JsonUtil::isoConvert).toList()));
+  }
+
+  @Override
+  public void activate() {
+    super.activate();
+    srcEnvelope.gatewayId = distributor.getRouteId(containerId);
+    info("Activated cron as %s", stringifyTerse(srcEnvelope));
+  }
+}
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/core/DistributorPipe.java b/udmis/src/main/java/com/google/bos/udmi/service/core/DistributorPipe.java
index 78079333c7..cbae5445be 100644
--- a/udmis/src/main/java/com/google/bos/udmi/service/core/DistributorPipe.java
+++ b/udmis/src/main/java/com/google/bos/udmi/service/core/DistributorPipe.java
@@ -1,7 +1,6 @@
 package com.google.bos.udmi.service.core;
 
 import static com.google.udmi.util.GeneralUtils.deepCopy;
-import static com.google.udmi.util.GeneralUtils.friendlyStackTrace;
 import static com.google.udmi.util.JsonUtil.stringifyTerse;
 import static java.lang.String.format;
 
@@ -41,12 +40,15 @@ public DistributorPipe(EndpointConfiguration config) {
   @Override
   protected void defaultHandler(Object message) {
     Envelope envelope = getContinuation(message).getEnvelope();
+    debug("Handling distribution from " + stringifyTerse(envelope));
     try {
       String[] routeId = envelope.gatewayId.split(ROUTE_SEPERATOR, 2);
       if (clientId.equals(routeId[0])) {
+        debug("Rejecting loopback client " + clientId);
         return;
       }
       Object component = UdmiServicePod.getComponent(routeId[1]);
+      debug("Routing result to " + component.getClass().getSimpleName());
       if (component instanceof ProcessorBase processorBase) {
         processorBase.processMessage(envelope, message);
       } else {
@@ -63,14 +65,17 @@ protected void defaultHandler(Object message) {
   public void publish(Envelope rawEnvelope, Object message, String source) {
     try {
       Envelope envelope = deepCopy(rawEnvelope);
-      String routeId = format("%s%s%s", clientId, ROUTE_SEPERATOR, source);
+      String routeId = getRouteId(source);
       debug("Distributing %s for %s/%s as %s", message.getClass().getSimpleName(),
           envelope.deviceRegistryId, envelope.deviceId, routeId);
       envelope.gatewayId = routeId;
-      super.publish(envelope, message);
+      publish(envelope, message);
     } catch (Exception e) {
-      error("Error distributing update: " + friendlyStackTrace(e));
+      throw new RuntimeException("Error distributing update", e);
     }
   }
 
+  public String getRouteId(String source) {
+    return format("%s%s%s", clientId, ROUTE_SEPERATOR, source);
+  }
 }
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/pod/ContainerBase.java b/udmis/src/main/java/com/google/bos/udmi/service/pod/ContainerBase.java
index ebe85cb170..fd9165b9a9 100644
--- a/udmis/src/main/java/com/google/bos/udmi/service/pod/ContainerBase.java
+++ b/udmis/src/main/java/com/google/bos/udmi/service/pod/ContainerBase.java
@@ -15,6 +15,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.udmi.util.JsonUtil;
 import java.io.PrintStream;
+import java.time.Duration;
 import java.util.Arrays;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
@@ -157,6 +158,11 @@ private void periodicTaskWrapper() {
   }
 
   protected void periodicTask() {
+    if (scheduledExecutor != null && !scheduledExecutor.isShutdown()) {
+      debug("Shutting down unused scheduled executor");
+      scheduledExecutor.shutdown();
+      return;
+    }
     throw new IllegalStateException("Unexpected periodic task execution");
   }
 
@@ -225,6 +231,10 @@ public void activate() {
     });
   }
 
+  protected void scheduleIn(Duration duration, Runnable task) {
+    scheduledExecutor.schedule(task, duration.getSeconds(), TimeUnit.SECONDS);
+  }
+
   public void debug(String format, Object... args) {
     debug(format(format, args));
   }
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/pod/UdmiServicePod.java b/udmis/src/main/java/com/google/bos/udmi/service/pod/UdmiServicePod.java
index c7106bb3ed..60b50db18c 100644
--- a/udmis/src/main/java/com/google/bos/udmi/service/pod/UdmiServicePod.java
+++ b/udmis/src/main/java/com/google/bos/udmi/service/pod/UdmiServicePod.java
@@ -7,7 +7,6 @@
 import static com.google.udmi.util.GeneralUtils.friendlyStackTrace;
 import static com.google.udmi.util.GeneralUtils.ifNotNullGet;
 import static com.google.udmi.util.GeneralUtils.ifNotNullThen;
-import static com.google.udmi.util.GeneralUtils.ifNotNullThrow;
 import static com.google.udmi.util.JsonUtil.loadFileStrictRequired;
 import static java.lang.String.format;
 import static java.util.Objects.requireNonNull;
@@ -15,7 +14,7 @@
 import com.google.bos.udmi.service.access.IotAccessProvider;
 import com.google.bos.udmi.service.core.BridgeProcessor;
 import com.google.bos.udmi.service.core.ControlProcessor;
-import com.google.bos.udmi.service.core.CronJob;
+import com.google.bos.udmi.service.core.CronProcessor;
 import com.google.bos.udmi.service.core.DistributorPipe;
 import com.google.bos.udmi.service.core.ProcessorBase;
 import com.google.bos.udmi.service.core.ReflectProcessor;
@@ -63,10 +62,10 @@ public UdmiServicePod(String[] args) {
     try {
       checkState(args.length == 1, "expected exactly one argument: configuration_file");
 
+      ifNotNullThen(podConfiguration.distributors, dist -> dist.forEach(this::createDistributor));
+      ifNotNullThen(podConfiguration.iot_access, access -> access.forEach(this::createAccess));
       ifNotNullThen(podConfiguration.flows, flows -> flows.forEach(this::createFlow));
       ifNotNullThen(podConfiguration.bridges, bridges -> bridges.forEach(this::createBridge));
-      ifNotNullThen(podConfiguration.iot_access, access -> access.forEach(this::createAccess));
-      ifNotNullThen(podConfiguration.distributors, dist -> dist.forEach(this::createDistributor));
       ifNotNullThen(podConfiguration.crons, dist -> dist.forEach(this::createCron));
     } catch (Exception e) {
       throw new RuntimeException("Fatal error instantiating pod " + CSV_JOINER.join(args), e);
@@ -184,7 +183,7 @@ private static void setConfigName(EndpointConfiguration config, String name) {
 
   private void createCron(String name, EndpointConfiguration config) {
     setConfigName(config, name);
-    putComponent(name, () -> ProcessorBase.create(CronJob.class, makeConfig(config)));
+    putComponent(name, () -> ProcessorBase.create(CronProcessor.class, makeConfig(config)));
   }
 
   private void createDistributor(String name, EndpointConfiguration config) {