diff --git a/src/NodeHeizung.h b/src/NodeHeizung.h
index 9abde7c..5f00e10 100644
--- a/src/NodeHeizung.h
+++ b/src/NodeHeizung.h
@@ -7,7 +7,7 @@
 #include "patrix/sensor/DHT22.h"
 #include "patrix/sensor/Max6675Sensor.h"
 
-class NodeHeizung final : public Node {
+class NodeHeizung final : public Node<100, 14> {
 
   const unsigned long MAX_AGE_SECONDS = 10;
 
diff --git a/src/NodeTest.h b/src/NodeTest.h
index 959a326..a8e8c54 100644
--- a/src/NodeTest.h
+++ b/src/NodeTest.h
@@ -1,12 +1,14 @@
 #ifndef NODE_TEST_H
 #define NODE_TEST_H
 
+#include <AsyncWebSocket.h>
+
 #include "patrix/Node.h"
 #include "patrix/sensor/Dallas.h"
 #include "patrix/sensor/DallasSensor.h"
 #include "patrix/sensor/DHT22.h"
 
-class NodeTest final : public Node {
+class NodeTest final : public Node<100, 4> {
 
   const unsigned long MAX_AGE_SECONDS = 10;
 
diff --git a/src/patrix/Cache.h b/src/patrix/Cache.h
new file mode 100644
index 0000000..c6630e9
--- /dev/null
+++ b/src/patrix/Cache.h
@@ -0,0 +1,82 @@
+#ifndef CACHE_H
+#define CACHE_H
+
+#include "log.h"
+
+template<size_t ENTRY_COUNT, size_t VALUE_COUNT>
+class Cache {
+
+public:
+
+  struct Entry {
+
+    time_t timestamp;
+
+    double data[VALUE_COUNT];
+
+  };
+
+private:
+
+  Entry entries[ENTRY_COUNT];
+
+  Entry *r = entries;
+
+  Entry *w = entries;
+
+  void clearWriteEntry() {
+    for (double& value: r->data) {
+      value = 0;
+    }
+  }
+
+  Entry *findEntry(time_t timestamp) {
+    if (w->timestamp == timestamp) {
+      return w;
+    }
+    auto wNext = (w + 1 - entries) % ENTRY_COUNT + entries;
+    if (w->timestamp == 0) {
+      w->timestamp = timestamp;
+      clearWriteEntry();
+    } else if (wNext != r) {
+      w = wNext;
+      w->timestamp = timestamp;
+      clearWriteEntry();
+    } else {
+      return nullptr;
+    }
+    return w;
+  }
+
+public:
+
+  void put(const time_t timestamp, const int valueIndex, const double value) {
+    if (valueIndex >= VALUE_COUNT) {
+      error("Cache.put: valueIndex to big for valueCount: valueIndex=%d, valueCount=%d", valueIndex, VALUE_COUNT);
+      return;
+    }
+    Entry *entry = findEntry(timestamp);
+    if (entry == nullptr) {
+      warn("Cache full!");
+      return;
+    }
+    entry->data[valueIndex] = value;
+  }
+
+  Entry *read() {
+    if (w != r || r->timestamp != 0) {
+      return r;
+    }
+    return nullptr;
+  }
+
+  void skip() {
+    if (w != r || w->timestamp != 0) {
+      r->timestamp = 0;
+      r = (r + 1 - entries) % ENTRY_COUNT + entries;
+    }
+  }
+
+};
+
+#endif
diff --git a/src/patrix/Node.h b/src/patrix/Node.h
index 3bf3f9e..a365d08 100644
--- a/src/patrix/Node.h
+++ b/src/patrix/Node.h
@@ -1,33 +1,38 @@
 #ifndef NODE_H
 #define NODE_H
 
+#include "Cache.h"
+#include "clock.h"
 #include "sensor/Sensor.h"
 
+template<size_t ENTRY_COUNT, size_t VALUE_COUNT>
 class Node {
 
+  Cache<ENTRY_COUNT, VALUE_COUNT> cache;
+
 public:
 
+  Node() : cache() {
+    //
+  }
+
   virtual ~Node() = default;
 
-  void toJson(const JsonObject& json) {
-    auto index = 0;
-    Sensor *sensor;
-    while ((sensor = getSensor(index++)) != nullptr) {
-      sensor->toJson(json[sensor->getName()].to<JsonObject>());
-    }
-  }
-
-  void send(const bool mqtt, const bool websocket) {
-    JsonDocument json;
-    toJson(json.to<JsonObject>());
-    mqttPublish(String(WiFiClass::getHostname()) + "/json", json, mqtt, websocket);
-  }
-
   void loop() {
     loopBeforeSensors();
-    const auto changed = loopSensors();
-    if (changed) {
-      send(true, true);
+    loopSensors();
+    cacheSend();
+  }
+
+  void websocketSendOne(AsyncWebSocketClient *client) {
+    auto sensorIndex = 0;
+    Sensor *sensor;
+    while ((sensor = this->getSensor(sensorIndex++)) != nullptr) {
+      auto valueIndex = 0;
+      Value *value;
+      while ((value = sensor->getValue(valueIndex++)) != nullptr) {
+        client->text(value->toJson(true));
+      }
     }
   }
 
@@ -39,16 +44,48 @@ public:
 
 private:
 
-  bool loopSensors() {
-    auto changed = false;
-    auto index = 0;
+  void loopSensors() {
+    const auto timestamp = time(nullptr);
+    auto cacheIndex = 0;
+    auto sensorIndex = 0;
     Sensor *sensor;
-    while ((sensor = getSensor(index++)) != nullptr) {
-      if (sensor->loop()) {
-        changed = true;
+    while ((sensor = getSensor(sensorIndex++)) != nullptr) {
+      auto valueIndex = 0;
+      Value *value;
+      while ((value = sensor->getValue(valueIndex++)) != nullptr) {
+        if (value->loop()) {
+          cache.put(timestamp, cacheIndex++, value->getCurrentValue());
+        }
       }
     }
-    return changed;
+  }
+
+  void cacheSend() {
+    const auto entry = cache.read();
+    if (entry == nullptr) {
+      return;
+    }
+
+    auto cacheIndex = 0;
+    auto sensorIndex = 0;
+    Sensor *sensor;
+    while ((sensor = getSensor(sensorIndex++)) != nullptr) {
+      auto valueIndex = 0;
+      Value *value;
+      while ((value = sensor->getValue(valueIndex++)) != nullptr) {
+        const auto v = entry->data[cacheIndex++];
+        const auto t = entry->timestamp;
+        if (isCorrectTime(t) && !isnan(v)) {
+          auto json = value->toJson(t, v, false);
+          if (mqttPublish(value->name + "/persist", json, NO_RETAIN)) {
+            entry->data[cacheIndex++] = NAN;
+          } else {
+            return;
+          }
+        }
+      }
+    }
+    cache.skip();
   }
 
 };
diff --git a/src/patrix/http.cpp b/src/patrix/http.cpp
index 9bcf311..f01b08c 100644
--- a/src/patrix/http.cpp
+++ b/src/patrix/http.cpp
@@ -2,10 +2,10 @@
 
 #include <ESPAsyncWebServer.h>
 
+#include "INDEX_HTML.h"
 #include "log.h"
 #include "main.h"
 #include "system.h"
-#include "INDEX_HTML.h"
 
 AsyncWebServer server(80);
 
@@ -31,7 +31,7 @@ void httpSetup() {
     switch (type) {
       case WS_EVT_CONNECT:
         t = "CONNECT";
-        node.send(false, true); // TODO this currently sends to ALL
+        node.websocketSendOne(client);
         break;
       case WS_EVT_DISCONNECT:
         t = "DISCONNECT";
@@ -62,6 +62,6 @@ void httpLoop() {
   ws.cleanupClients();
 }
 
-void httpPublish(char *payload) {
+void websocketSendAll(const String& payload) {
   ws.textAll(payload);
 }
diff --git a/src/patrix/http.h b/src/patrix/http.h
index e4c0a70..2b9aaf2 100644
--- a/src/patrix/http.h
+++ b/src/patrix/http.h
@@ -1,10 +1,12 @@
 #ifndef HTTP_H
 #define HTTP_H
 
+#include <Arduino.h>
+
 void httpSetup();
 
 void httpLoop();
 
-void httpPublish(char *payload);
+void websocketSendAll(const String& payload);
 
 #endif
diff --git a/src/patrix/main.cpp b/src/patrix/main.cpp
index 88cb7af..b4f77b4 100644
--- a/src/patrix/main.cpp
+++ b/src/patrix/main.cpp
@@ -7,9 +7,13 @@
 #include "mqtt.h"
 #include "wifi.h"
 
+// ReSharper disable CppUnusedIncludeDirective
 #include "sensor/DallasSensor.h"
 #include "sensor/DHT22.h"
 #include "sensor/Max6675Sensor.h"
+// ReSharper restore CppUnusedIncludeDirective
+
+// ReSharper disable CppUseAuto
 
 #ifdef NODE_TEST
 NodeTest node = NodeTest();
@@ -19,6 +23,8 @@ NodeTest node = NodeTest();
 NodeHeizung node = NodeHeizung();
 #endif
 
+// ReSharper restore CppUseAuto
+
 void setup() {
   logSetup();
   bootDelay();
diff --git a/src/patrix/main.h b/src/patrix/main.h
index 21fb2c8..029fda3 100644
--- a/src/patrix/main.h
+++ b/src/patrix/main.h
@@ -1,8 +1,10 @@
 #ifndef MAIN_H
 #define MAIN_H
 
-#include "NodeTest.h"
+// ReSharper disable CppUnusedIncludeDirective
 #include "NodeHeizung.h"
+#include "NodeTest.h"
+// ReSharper restore CppUnusedIncludeDirective
 
 #ifdef NODE_TEST
 extern NodeTest node;
diff --git a/src/patrix/mqtt.cpp b/src/patrix/mqtt.cpp
index aba8e98..d5ae64d 100644
--- a/src/patrix/mqtt.cpp
+++ b/src/patrix/mqtt.cpp
@@ -3,7 +3,6 @@
 #include <PubSubClient.h>
 #include <WiFi.h>
 
-#include "http.h"
 #include "log.h"
 #include "wifi.h"
 
@@ -47,19 +46,6 @@ void mqttLoop() {
   }
 }
 
-bool mqttPublish(const String& topic, const double value, const bool retained) {
-  return mqtt.publish(topic.c_str(), String(value).c_str(), retained);
-}
-
-
-bool mqttPublish(const String& topic, const JsonDocument& json, const bool mqttSend, const bool websocketSend) {
-  char buffer[512];
-  serializeJson(json, buffer);
-  if (websocketSend) {
-    httpPublish(buffer);
-  }
-  if (mqttSend) {
-    return mqtt.publish(topic.c_str(), buffer);
-  }
-  return true;
+bool mqttPublish(const String& topic, const String& payload, const Retain retain) {
+  return mqtt.publish(topic.c_str(), payload.c_str(), retain == RETAIN);
 }
diff --git a/src/patrix/mqtt.h b/src/patrix/mqtt.h
index a7f52af..1549a22 100644
--- a/src/patrix/mqtt.h
+++ b/src/patrix/mqtt.h
@@ -1,12 +1,14 @@
 #ifndef MQTT_H
 #define MQTT_H
 
-#include <ArduinoJson.h>
+#include <AsyncWebSocket.h>
+
+enum Retain {
+  NO_RETAIN, RETAIN
+};
 
 void mqttLoop();
 
-bool mqttPublish(const String& topic, const double value, bool retained);
-
-bool mqttPublish(const String& topic, const JsonDocument& json, bool mqtt, bool websocketSend);
+bool mqttPublish(const String& topic, const String& payload, Retain retain);
 
 #endif
diff --git a/src/patrix/sensor/DHT22.h b/src/patrix/sensor/DHT22.h
index b77eb99..30b2a18 100644
--- a/src/patrix/sensor/DHT22.h
+++ b/src/patrix/sensor/DHT22.h
@@ -19,7 +19,7 @@ class DHT22 final : public Sensor {
 public:
 
   DHT22(const int pin,
-        const char *name,
+        const String& name,
         const double temperatureThreshold,
         const double humidityRelativeThreshold,
         const double humidityAbsoluteThreshold,
@@ -27,9 +27,9 @@ public:
         const unsigned long overdueSeconds
   ) : Sensor(name),
       sensor(pin, DHT_TYPE_22),
-      temperature(name, "temperature", temperatureThreshold, maxAgeSeconds, overdueSeconds),
-      humidityRelative(name, "humidity/relative", humidityRelativeThreshold, maxAgeSeconds, overdueSeconds),
-      humidityAbsolute(name, "humidity/absolute", humidityAbsoluteThreshold, maxAgeSeconds, overdueSeconds) {
+      temperature(name + "/temperature", temperatureThreshold, maxAgeSeconds, overdueSeconds),
+      humidityRelative(name + "/humidity/relative", humidityRelativeThreshold, maxAgeSeconds, overdueSeconds),
+      humidityAbsolute(name + "/humidity/absolute", humidityAbsoluteThreshold, maxAgeSeconds, overdueSeconds) {
     //
   }
 
diff --git a/src/patrix/sensor/DallasSensor.h b/src/patrix/sensor/DallasSensor.h
index 191fde6..fd4c5a3 100644
--- a/src/patrix/sensor/DallasSensor.h
+++ b/src/patrix/sensor/DallasSensor.h
@@ -19,14 +19,14 @@ public:
   DallasSensor(
     Dallas& sensors,
     const uint64_t address,
-    const char *name,
+    const String& name,
     const double threshold,
     const unsigned long maxAgeSeconds,
     const unsigned long overdueSeconds
   ) : Sensor(name),
       sensors(sensors),
       address(address),
-      temperature(name, "temperature", threshold, maxAgeSeconds, overdueSeconds) {
+      temperature(name + "/temperature", threshold, maxAgeSeconds, overdueSeconds) {
     //
   }
 
diff --git a/src/patrix/sensor/Max6675Sensor.h b/src/patrix/sensor/Max6675Sensor.h
index bd9cb55..7d9260d 100644
--- a/src/patrix/sensor/Max6675Sensor.h
+++ b/src/patrix/sensor/Max6675Sensor.h
@@ -20,13 +20,13 @@ public:
     const int8_t pinMISO,
     const int8_t pinCS,
     const int8_t pinCLK,
-    const char *name,
+    const String& name,
     const double threshold,
     const unsigned long maxAgeSeconds,
     const unsigned long overdueSeconds
   ) : Sensor(name),
       sensor(pinCLK, pinCS, pinMISO),
-      temperature(name, "temperature", threshold, maxAgeSeconds, overdueSeconds) {
+      temperature(name + "/temperature", threshold, maxAgeSeconds, overdueSeconds) {
     //
   }
 
diff --git a/src/patrix/sensor/Sensor.h b/src/patrix/sensor/Sensor.h
index f18563c..50f5bbf 100644
--- a/src/patrix/sensor/Sensor.h
+++ b/src/patrix/sensor/Sensor.h
@@ -6,63 +6,20 @@
 
 class Sensor {
 
-protected:
-
-  const char *name;
-
 public:
 
-  explicit Sensor(const char *name): name(name) {
+  const String& name;
+
+  explicit Sensor(const String& name): name(name) {
     //
   }
 
   virtual ~Sensor() = default;
 
-  const char *getName() const {
-    return name;
-  }
-
-  bool loop() {
-    loopBeforeValues();
-    const auto changed = loopValues();
-    if (changed) {
-      send();
-    }
-    return changed;
-  }
-
-  void send() {
-    JsonDocument json;
-    toJson(json.to<JsonObject>());
-    mqttPublish(String(name) + "/json", json, true, false);
-  }
-
-  void toJson(const JsonObject& json) {
-    auto index = 0;
-    Value *value;
-    while ((value = getValue(index++)) != nullptr) {
-      value->toJson(json[value->getName()].to<JsonObject>());
-    }
-  }
-
   virtual void loopBeforeValues() {}
 
   virtual Value *getValue(int index) = 0;
 
-private:
-
-  bool loopValues() {
-    auto changed = false;
-    auto index = 0;
-    Value *value;
-    while ((value = getValue(index++)) != nullptr) {
-      if (value->loop()) {
-        changed = true;
-      }
-    }
-    return changed;
-  }
-
 };
 
 #endif
diff --git a/src/patrix/sensor/Value.h b/src/patrix/sensor/Value.h
index eb9a6d1..9606004 100644
--- a/src/patrix/sensor/Value.h
+++ b/src/patrix/sensor/Value.h
@@ -1,16 +1,13 @@
 #ifndef VALUE_H
 #define VALUE_H
 
-#include <WiFi.h>
+#include <ArduinoJson.h>
+#include <patrix/http.h>
 #include <patrix/log.h>
 #include <patrix/mqtt.h>
 
 class Value {
 
-  const char *parent;
-
-  const char *name;
-
   double threshold;
 
   unsigned long maxAgeMillis;
@@ -29,17 +26,17 @@ class Value {
 
 public:
 
+  const String name;
+
   Value(
-    const char *parent,
-    const char *name,
+    const String& name,
     const double threshold,
     const unsigned long maxAgeSeconds,
     const unsigned long overdueSeconds
-  ) : parent(parent),
-      name(name),
-      threshold(threshold),
+  ) : threshold(threshold),
       maxAgeMillis(maxAgeSeconds * 1000),
-      overdueSeconds(overdueSeconds) {
+      overdueSeconds(overdueSeconds),
+      name(name) {
     //
   }
 
@@ -49,24 +46,9 @@ public:
     currentEpoch = time(nullptr);
   }
 
-  void toJson(const JsonObject& json) const {
-    json["value"] = currentValue;
-    json["time"] = currentEpoch;
-  }
-
-  void send() {
-    mqttPublish(String(parent) + "/" + name + "/plain", currentValue, true);
-
-    JsonDocument json;
-    toJson(json.to<JsonObject>());
-    mqttPublish(String(parent) + "/" + name + "/json", json, true, false);
-
-    markSent();
-  }
-
   bool loop() {
     if (!isnan(currentValue) && millis() - currentMillis > maxAgeMillis) {
-      warn("Value too old: %s/%s", parent, name);
+      warn("Value too old: %s", name.c_str());
       update(NAN);
     }
 
@@ -75,28 +57,33 @@ public:
     const auto dueToTime = sentInterval != 0 && sentInterval != time(nullptr) / overdueSeconds;
     const auto changed = dueToNAN || dueToThreshold || dueToTime;
     if (changed) {
-      send();
+      mqttPublish(name + "/retain", String(currentValue), RETAIN);
+      websocketSendAll(toJson(false));
+      sentValue = currentValue;
+      sentInterval = time(nullptr) / overdueSeconds;
     }
     return changed;
   }
 
-  const char *getName() const {
-    return name;
-  }
-
   double getCurrentValue() const {
     return currentValue;
   }
 
-  time_t getCurrentEpoch() const {
-    return currentEpoch;
+  String toJson(const bool addNameField) const {
+    return toJson(currentEpoch, currentValue, addNameField);
   }
 
-private:
+  String toJson(const time_t timestamp, const double value, const bool addNameField) const {
+    JsonDocument json;
+    if (addNameField) {
+      json["name"] = name.c_str();
+    }
+    json["timestamp"] = timestamp;
+    json["value"] = value;
 
-  void markSent() {
-    sentValue = currentValue;
-    sentInterval = time(nullptr) / overdueSeconds;
+    char buffer[256];
+    serializeJson(json, buffer, sizeof buffer);
+    return String(buffer);
   }
 
 };