diff --git a/src/main/java/com/epita/guereza/App.java b/src/main/java/com/epita/guereza/App.java
index df18d7f..aa44be5 100644
--- a/src/main/java/com/epita/guereza/App.java
+++ b/src/main/java/com/epita/guereza/App.java
@@ -3,6 +3,7 @@
 import com.epita.eventbus.EventBusClient;
 import com.epita.eventbus.EventMessage;
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -48,4 +49,13 @@ protected void retryIn(final int seconds, Runnable consumer) {
         executor.schedule(consumer, seconds, TimeUnit.SECONDS);
         executor.shutdownNow();
     }
+
+    protected Object mappingObject(EventBusClient.Message message) {
+        try {
+            Class c = ClassLoader.getSystemClassLoader().loadClass(message.getMessageType());
+            return new ObjectMapper().readValue(message.getContent(), c);
+        } catch (Exception e) {
+            return null;
+        }
+    }
 }
diff --git a/src/main/java/com/epita/guereza/CrawlerApp.java b/src/main/java/com/epita/guereza/CrawlerApp.java
index 825c064..679fad8 100644
--- a/src/main/java/com/epita/guereza/CrawlerApp.java
+++ b/src/main/java/com/epita/guereza/CrawlerApp.java
@@ -41,17 +41,13 @@ private void storeUrls(final String[] urls) {
     public void run() {
         eventBus.subscribe(subscribeUrl, msg -> {
             if (msg != null) {
-                try {
-                    Class c = ClassLoader.getSystemClassLoader().loadClass(msg.getMessageType());
-                    String url = (String)new ObjectMapper().readValue(msg.getContent(), c);
+                String url = (String)mappingObject(msg);
+                if (url != null) {
                     LOGGER.info("Receive url: {}", url);
                     final String[] urls = crawlAndExtract(url);
                     storeUrls(urls);
-                } catch (Exception e) {
-                    e.printStackTrace();
                 }
 
-
                 requestNextUrl();
             } else {
                 retryIn(30, this::requestNextUrl);
diff --git a/src/main/java/com/epita/guereza/IndexerApp.java b/src/main/java/com/epita/guereza/IndexerApp.java
index e26f38b..96f942a 100644
--- a/src/main/java/com/epita/guereza/IndexerApp.java
+++ b/src/main/java/com/epita/guereza/IndexerApp.java
@@ -50,8 +50,11 @@ private void requestNextUrl() {
     public void run() {
         eventBus.subscribe(subscribeUrl, msg -> {
             if (msg != null) {
-                LOGGER.info("Receive url: {}", msg.getContent());
-                indexAndPublish(msg.getContent());
+                String url = (String)mappingObject(msg);
+                if (url != null) {
+                    LOGGER.info("Receive url: {}", url);
+                    indexAndPublish(url);
+                }
 
                 requestNextUrl();
             } else {