diff --git a/Documentation/Diagrammes/diagrammes.asta b/Documentation/Diagrammes/diagrammes.asta
index 28865cbb..fd5ff37d 100644
Binary files a/Documentation/Diagrammes/diagrammes.asta and b/Documentation/Diagrammes/diagrammes.asta differ
diff --git a/Workspace/core/src/main/java/com/pqt/core/entities/messages/Field.java b/Workspace/core/src/main/java/com/pqt/core/entities/messages/Field.java
deleted file mode 100644
index a40f74cb..00000000
--- a/Workspace/core/src/main/java/com/pqt/core/entities/messages/Field.java
+++ /dev/null
@@ -1,22 +0,0 @@
-package com.pqt.core.entities.messages;
-
-import java.io.Serializable;
-
-public class Field implements Serializable{
-
-	private String header;
-	private String data;
-
-	public Field(String header, String data) {
-		this.header = header;
-		this.data = data;
-	}
-
-	public String getHeader() {
-		return header;
-	}
-
-	public String getData() {
-		return data;
-	}
-}
diff --git a/Workspace/core/src/main/java/com/pqt/core/entities/messages/Message.java b/Workspace/core/src/main/java/com/pqt/core/entities/messages/Message.java
index 26ce58f4..78080326 100644
--- a/Workspace/core/src/main/java/com/pqt/core/entities/messages/Message.java
+++ b/Workspace/core/src/main/java/com/pqt/core/entities/messages/Message.java
@@ -3,11 +3,13 @@ package com.pqt.core.entities.messages;
 import com.pqt.core.entities.members.PqtMember;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class Message {
 
-    private List<Field> fields;
+    private Map<String, String> fields;
     private MessageType type;
     private PqtMember emitter, receiver;
 
@@ -15,17 +17,27 @@ public class Message {
         this(type, emitter, receiver, null);
     }
 
-    public Message(MessageType type, PqtMember emitter, PqtMember receiver, List<Field> fields) {
+    public Message(MessageType type, PqtMember emitter, PqtMember receiver, Map<String, String> fields) {
         this.emitter = emitter;
         this.receiver = receiver;
         this.type = type;
-        this.fields = new ArrayList<>();
+        this.fields = new HashMap<>();
         if(fields!=null)
-            this.fields.addAll(fields);
+            for(String key : fields.keySet()){
+                this.fields.put(key, fields.get(key));
+            }
     }
 
-    public List<Field> getFields() {
-        return new ArrayList<>(fields);
+    public Map<String, String> getFields() {
+        return new HashMap<>(fields);
+    }
+
+    public boolean hasField(String header){
+        return fields.containsKey(header);
+    }
+
+    public String getField(String header){
+        return fields.get(header);
     }
 
     public PqtMember getEmitter() {