diff --git a/POO_Server/src/main/Main.java b/POO_Server/src/main/Main.java
new file mode 100644
index 0000000..06cc0f6
--- /dev/null
+++ b/POO_Server/src/main/Main.java
@@ -0,0 +1,5 @@
+package main;
+
+public class Main {
+
+}
diff --git a/POO_Server/src/main/ServletPresence.java b/POO_Server/src/main/ServletPresence.java
new file mode 100644
index 0000000..ce78ade
--- /dev/null
+++ b/POO_Server/src/main/ServletPresence.java
@@ -0,0 +1,41 @@
+package main;
+
+//il faut lier le serveur tomcat, voir avec K ou le prof
+import java.io.IOException;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Servlet implementation class ServletPresence
+ */
+@WebServlet("/ServletPresence")
+public class ServletPresence extends HttpServlet {
+	private static final long serialVersionUID = 1L;
+
+    /**
+     * Default constructor. 
+     */
+    public ServletPresence() {
+        // TODO Auto-generated constructor stub
+    }
+
+	/**
+	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
+	 */
+	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+		// TODO Auto-generated method stub
+		response.getWriter().append("Served at: ").append(request.getContextPath());
+	}
+
+	/**
+	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
+	 */
+	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+		// TODO Auto-generated method stub
+		doGet(request, response);
+	}
+
+}
diff --git a/POO_Server/src/messages/MauvaisTypeMessageException.java b/POO_Server/src/messages/MauvaisTypeMessageException.java
new file mode 100644
index 0000000..c7f9644
--- /dev/null
+++ b/POO_Server/src/messages/MauvaisTypeMessageException.java
@@ -0,0 +1,8 @@
+package messages;
+
+public class MauvaisTypeMessageException extends Exception {
+
+	private static final long serialVersionUID = 1L;
+
+
+}
diff --git a/POO_Server/src/messages/Message.java b/POO_Server/src/messages/Message.java
new file mode 100644
index 0000000..4afae87
--- /dev/null
+++ b/POO_Server/src/messages/Message.java
@@ -0,0 +1,69 @@
+package messages;
+
+import java.io.Serializable;
+import java.lang.instrument.Instrumentation;
+import java.util.Arrays;
+
+import messages.Message.TypeMessage;
+
+public abstract class Message implements Serializable {
+
+	public enum TypeMessage {JE_SUIS_CONNECTE, JE_SUIS_DECONNECTE, INFO_PSEUDO, TEXTE, IMAGE, FICHIER, MESSAGE_NUL}
+	protected TypeMessage type;
+	private static final long serialVersionUID = 1L;
+	private static Instrumentation inst;
+
+	public TypeMessage getTypeMessage() {
+		return this.type;
+	}
+
+	protected abstract String attributsToString();
+
+	public String toString() {
+		return this.type+"###"+this.attributsToString();
+	}	
+
+	public static Message stringToMessage(String messageString) {
+		try {
+			String[] parts = messageString.split("###");
+			switch (parts[0]) {
+			case "JE_SUIS_CONNECTE" :
+				return new MessageSysteme(TypeMessage.JE_SUIS_CONNECTE);
+				
+			case "JE_SUIS_DECONNECTE" :
+				return new MessageSysteme(TypeMessage.JE_SUIS_DECONNECTE);
+				
+			case "INFO_PSEUDO" :
+				return new MessageSysteme(TypeMessage.INFO_PSEUDO, parts[1], parts[2]);
+				
+			case "TEXTE" :
+				return new MessageTexte(TypeMessage.TEXTE, parts[1]);
+				
+			case "IMAGE" :
+				return new MessageFichier(TypeMessage.IMAGE, parts[1], parts[2]);
+				
+			case "FICHIER" :
+				return new MessageFichier(TypeMessage.FICHIER, parts[1], parts[2]);
+			}
+		} catch (MauvaisTypeMessageException e) {}
+			return null;
+	}
+
+	//tests ici
+	public static void main(String[] args) throws MauvaisTypeMessageException {		
+		Message m1 = new MessageSysteme(TypeMessage.JE_SUIS_CONNECTE);
+		Message m2 = new MessageSysteme(TypeMessage.JE_SUIS_DECONNECTE);
+		Message m3 = new MessageSysteme(TypeMessage.INFO_PSEUDO, "pseudo156434518", "id236");
+		Message m4 = new MessageTexte(TypeMessage.TEXTE, "blablabla");
+		Message m5 = new MessageFichier(TypeMessage.FICHIER, "truc", ".pdf");
+		
+		
+		System.out.println(Message.stringToMessage(m1.toString()));
+		System.out.println(Message.stringToMessage(m2.toString()));
+		System.out.println(Message.stringToMessage(m3.toString()));
+		System.out.println(Message.stringToMessage(m4.toString()));
+		System.out.println(Message.stringToMessage(m5.toString()));
+		
+	}
+
+}
diff --git a/POO_Server/src/messages/MessageFichier.java b/POO_Server/src/messages/MessageFichier.java
new file mode 100644
index 0000000..aa8f0bf
--- /dev/null
+++ b/POO_Server/src/messages/MessageFichier.java
@@ -0,0 +1,33 @@
+package messages;
+
+import messages.Message.TypeMessage;
+
+public class MessageFichier extends Message {
+	
+
+	private static final long serialVersionUID = 1L;
+	private String contenu;
+	private String extension;
+
+	public MessageFichier(TypeMessage type, String contenu, String extension) throws MauvaisTypeMessageException{
+		if ((type==TypeMessage.IMAGE)||(type==TypeMessage.FICHIER)) {
+			this.type=type;
+			this.contenu=contenu;
+			this.extension=extension;
+		}
+		else throw new MauvaisTypeMessageException();
+	}
+
+	public String getContenu() {
+		return this.contenu;
+	}
+	
+	public String getExtension() {
+		return this.extension;
+	}
+
+	@Override
+	protected String attributsToString() {
+		return this.contenu+"###"+this.extension;
+	}
+}
\ No newline at end of file
diff --git a/POO_Server/src/messages/MessageSysteme.java b/POO_Server/src/messages/MessageSysteme.java
new file mode 100644
index 0000000..dcda974
--- /dev/null
+++ b/POO_Server/src/messages/MessageSysteme.java
@@ -0,0 +1,39 @@
+package messages;
+
+public class MessageSysteme extends Message {
+	
+	private static final long serialVersionUID = 1L;
+	private String pseudo;
+	private String id;
+
+	public MessageSysteme(TypeMessage type) throws MauvaisTypeMessageException{
+		if ((type==TypeMessage.JE_SUIS_CONNECTE)||(type==TypeMessage.JE_SUIS_DECONNECTE)||(type==TypeMessage.MESSAGE_NUL)) {
+			this.type=type;
+			this.pseudo="";
+			this.id="";
+		}
+		else throw new MauvaisTypeMessageException();
+	}
+	
+	public MessageSysteme(TypeMessage type, String pseudo, String id) throws MauvaisTypeMessageException {
+		if (type==TypeMessage.INFO_PSEUDO) {
+			this.type=type;
+			this.pseudo=pseudo;
+			this.id=id;
+		}
+		else throw new MauvaisTypeMessageException();
+	}
+	
+	public String getPseudo() {
+		return this.pseudo;
+	}
+	
+	public String getId() {
+		return this.id;
+	}
+
+	@Override
+	protected String attributsToString() {
+		return this.pseudo+"###"+this.id;
+	}
+}
diff --git a/POO_Server/src/messages/MessageTexte.java b/POO_Server/src/messages/MessageTexte.java
new file mode 100644
index 0000000..e5d354d
--- /dev/null
+++ b/POO_Server/src/messages/MessageTexte.java
@@ -0,0 +1,27 @@
+package messages;
+
+import messages.Message.TypeMessage;
+
+public class MessageTexte extends Message {
+	
+
+	private static final long serialVersionUID = 1L;
+	private String contenu;
+
+	public MessageTexte(TypeMessage type, String contenu) throws MauvaisTypeMessageException{
+		if (type==TypeMessage.TEXTE) {
+			this.type=type;
+			this.contenu=contenu;
+		}
+		else throw new MauvaisTypeMessageException();
+	}
+
+	public String getContenu() {
+		return this.contenu;
+	}
+
+	@Override
+	protected String attributsToString() {
+		return this.contenu;
+	}
+}
\ No newline at end of file