diff --git a/src/main/java/fr/isae/iqas/model/observation/Knowledge.java b/src/main/java/fr/isae/iqas/model/observation/Knowledge.java
index df78247f..69f619a1 100644
--- a/src/main/java/fr/isae/iqas/model/observation/Knowledge.java
+++ b/src/main/java/fr/isae/iqas/model/observation/Knowledge.java
@@ -96,6 +96,19 @@ public String toString() {
         }
     }
 
+    @Override
+    public void addTimestamp(String stepName, long timestamp) {
+        Individual obsValueInd = obsModel.getIndividual( pref.get("qoo") + "obsValue");
+        String previousValue = obsValueInd.getProperty(qooP.get("qoo:obsTimestampsValue")).getString();
+        if (previousValue.equals("")) {
+            previousValue = previousValue.concat(stepName + ":" + String.valueOf(timestamp));
+        }
+        else {
+            previousValue = previousValue.concat(";" + stepName + ":" + String.valueOf(timestamp));
+        }
+        obsValueInd.setPropertyValue(qooP.get("qoo:obsTimestampsValue"), obsModel.createLiteral(previousValue));
+    }
+
     /**
      * Getters and setters for a specific QoO attribute
      */
diff --git a/src/main/java/fr/isae/iqas/model/observation/RawData.java b/src/main/java/fr/isae/iqas/model/observation/RawData.java
index 61a23254..605809e6 100644
--- a/src/main/java/fr/isae/iqas/model/observation/RawData.java
+++ b/src/main/java/fr/isae/iqas/model/observation/RawData.java
@@ -103,12 +103,12 @@ public String getTimestamps() {
         return timestamps;
     }
 
-    public void addTimestamp(String stepName, String timestampString) {
+    public void addTimestamp(String stepName, long timestamp) {
         if (this.timestamps.equals("")) {
-            this.timestamps = this.timestamps.concat(stepName + ":" + timestampString);
+            this.timestamps = this.timestamps.concat(stepName + ":" + String.valueOf(timestamp));
         }
         else {
-            this.timestamps = this.timestamps.concat(";" + stepName + ":" + timestampString);
+            this.timestamps = this.timestamps.concat(";" + stepName + ":" + String.valueOf(timestamp));
         }
     }
 
diff --git a/src/main/java/fr/isae/iqas/pipelines/OutputPipeline.java b/src/main/java/fr/isae/iqas/pipelines/OutputPipeline.java
index 00530acc..0fe1493f 100644
--- a/src/main/java/fr/isae/iqas/pipelines/OutputPipeline.java
+++ b/src/main/java/fr/isae/iqas/pipelines/OutputPipeline.java
@@ -166,9 +166,7 @@ public Graph<FlowShape<ConsumerRecord<byte[], String>, ProducerRecord<byte[], St
                                     sensorDataObject.getString("date"),
                                     sensorDataObject.getString("value"),
                                     sensorDataObject.getString("producer"),
-                                    sensorDataObject.getString("timestamps"),
-                                    "iQAS_out",
-                                    System.currentTimeMillis());
+                                    sensorDataObject.getString("timestamps"));
 
                             if (getQooParams().size() > 0) {
                                 if (interestAttr.contains(OBS_ACCURACY)) {
@@ -193,7 +191,10 @@ public Graph<FlowShape<ConsumerRecord<byte[], String>, ProducerRecord<byte[], St
                 );
 
                 final FlowShape<RawData, ProducerRecord> rawDataToProdRecord = builder.add(
-                        Flow.of(RawData.class).map(r -> new ProducerRecord<byte[], String>(getTopicToPublish(), mapper.writeValueAsString(r)))
+                        Flow.of(RawData.class).map(r -> {
+                            r.addTimestamp("iQAS_out", System.currentTimeMillis());
+                            return new ProducerRecord<byte[], String>(getTopicToPublish(), mapper.writeValueAsString(r));
+                        })
                 );
 
                 builder.from(consumRecordToRawData.out())
@@ -218,9 +219,7 @@ public Graph<FlowShape<ConsumerRecord<byte[], String>, ProducerRecord<byte[], St
                                     sensorDataObject.getString("date"),
                                     sensorDataObject.getString("value"),
                                     producer,
-                                    sensorDataObject.getString("timestamps"),
-                                    "iQAS_out",
-                                    System.currentTimeMillis());
+                                    sensorDataObject.getString("timestamps"));
 
                             if (getQooParams().size() > 0) {
                                 if (interestAttr.contains(OBS_ACCURACY)) {
@@ -249,7 +248,10 @@ public Graph<FlowShape<ConsumerRecord<byte[], String>, ProducerRecord<byte[], St
                 );
 
                 final FlowShape<Information, ProducerRecord> infoToProdRecord = builder.add(
-                        Flow.of(Information.class).map(r -> new ProducerRecord<byte[], String>(getTopicToPublish(), mapper.writeValueAsString(r)))
+                        Flow.of(Information.class).map(r -> {
+                            r.addTimestamp("iQAS_out", System.currentTimeMillis());
+                            return new ProducerRecord<byte[], String>(getTopicToPublish(), mapper.writeValueAsString(r));
+                        })
                 );
 
                 builder.from(consumRecordToInfo.out())
@@ -274,9 +276,7 @@ else if (askedLevelFinal == KNOWLEDGE) {
                                     sensorDataObject.getString("date"),
                                     sensorDataObject.getString("value"),
                                     sensorDataObject.getString("producer"),
-                                    sensorDataObject.getString("timestamps"),
-                                    "iQAS_out",
-                                    System.currentTimeMillis());
+                                    sensorDataObject.getString("timestamps"));
 
                             if (getQooParams().size() > 0) {
                                 if (interestAttr.contains(OBS_ACCURACY)) {
@@ -320,6 +320,7 @@ else if (askedLevelFinal == KNOWLEDGE) {
                                 }
                             }
 
+                            knowledgeTemp.addTimestamp("iQAS_out", System.currentTimeMillis());
                             return new ProducerRecord<byte[], String>(getTopicToPublish(), knowledgeTemp.toString());
                         })
                 );
diff --git a/src/main/resources/web/js/script_view_request.js b/src/main/resources/web/js/script_view_request.js
index 95ca6fa3..e54a4c0c 100644
--- a/src/main/resources/web/js/script_view_request.js
+++ b/src/main/resources/web/js/script_view_request.js
@@ -246,6 +246,7 @@ $(function () {
                 }],
                 yAxes: [{
                     id: 'A',
+                    label: 'freshness (ms)',
                     type: 'linear',
                     position: 'left',
                     ticks: {
@@ -253,6 +254,7 @@ $(function () {
                     }
                 }, {
                     id: 'B',
+                    label: 'accuracy (%)',
                     type: 'linear',
                     position: 'right',
                     ticks: {