diff --git a/endtoend_test.go b/endtoend_test.go
index e94b225..826e1bd 100644
--- a/endtoend_test.go
+++ b/endtoend_test.go
@@ -8,6 +8,7 @@ import (
 
 	"forge.redroom.link/yves/meowlib"
 	"forge.redroom.link/yves/meowlib/client"
+	"forge.redroom.link/yves/meowlib/server"
 )
 
 func TestEndToEnd(t *testing.T) {
@@ -112,17 +113,40 @@ func TestEndToEnd(t *testing.T) {
 		///////////////////////////////////////
 		// Simulating server side processing //
 		///////////////////////////////////////
+		var server1 server.Identity
+		server1.ServerName = intS1.ServerData.Name
+		server1.ServerKp = FriendServer1KP
+		server1.ServerDesc = intS1.ServerData.Description
+		// Unpack
+		srv_from, srv_encmsg, srv_signature, err := server1.UnpackReceived(protoPackedServerMsg)
+		// Decrypt
+		srv_clear, err := server1.AsymDecryptMessage(srv_from, srv_encmsg, srv_signature)
+		// Decode msg
+		srv_msg, err := server1.DecodeToServerMessage(srv_clear)
+		// Response : Ack received message
+		srv_fromServerMessage, err := server1.BuildSimpleAckResponseMessage(srv_msg.Uuid)
+		srv_resp, srv_respsig, err := server1.AsymEncryptMessage(srv_from, srv_fromServerMessage)
+		resp, err := server1.PackResponseMessage(srv_resp, srv_respsig)
 
 		//////////////////////////////////////////////
 		// Back to client, decoding server response //
 		//////////////////////////////////////////////
 
-		//
+		// server unpack
+
+		// server decrypt
+
+		// server decode protobuf
+
+		// user unpack
+
+		// user decrypt
 		decMess, err2 := MyFirstFriend.AsymDecryptMessage([]byte(EncMsg), EncMsgSignature)
 		if err2 != nil {
 			fmt.Println(err2.Error())
 		}
 		fmt.Println(decMess)
+		// user decode protobuf
 
 	}
 
diff --git a/pb/messages.proto b/pb/messages.proto
index ddf2088..24a35e8 100644
--- a/pb/messages.proto
+++ b/pb/messages.proto
@@ -11,7 +11,7 @@ message PackedServerMessage {
 
 // structure defining a message for a server, that will be encrypted, then sent in a "packedmessage" payload
 message ToServerMessage {
-	string type = 1; // Type 
+	string type = 1; // Type 1 : final destination / 2 : forward 
 	string from = 2 ; // My pub key for the server to send me an encrypter answer
 	bytes payload = 3 ; // optional payload for server
 
@@ -28,6 +28,7 @@ message ToServerMessage {
 	repeated PackedUserMessage messages = 5; 
 
     repeated Server knownServers = 6; 
+    
     string uuid = 7;
 
 }
@@ -83,16 +84,16 @@ message PackedUserMessage {
 
 // structure defining information that might be exchanged between two peers.
 message UserMessage {
-	string Destination = 1; 
-	string From = 2; 
-	string Type = 3; 
-	bytes Data = 4; 
+	string destination = 1; 
+	string from = 2; 
+	string type = 3; 
+	bytes data = 4; 
     message ConversationStatus {
-        string LocalUuid = 1; 
-        uint64 LocalSequence = 2 ;
-        uint64 Sent = 3 ; 
-        uint64 Received = 4; 
-        uint64 Processed = 5; 
+        string localUuid = 1; 
+        uint64 localSequence = 2 ;
+        uint64 sent = 3 ; 
+        uint64 received = 4; 
+        uint64 processed = 5; 
         ContactCard myNextIdentity = 6;
         int32  peerNextIdentityAck = 7; // version of the new peed accepted id
         }
diff --git a/server/identity.go b/server/identity.go
index 0a53f3b..6ab6c83 100644
--- a/server/identity.go
+++ b/server/identity.go
@@ -88,11 +88,15 @@ func (id *Identity) DecodeToServerMessage(toServerMessage []byte) (*meowlib.ToSe
 // Outbound processing chain
 //
 
-func (id *Identity) BuildSimpleAckResponseMessage(uuidToAck string) (fromServerMessage *meowlib.FromServerMessage, err error) {
+func (id *Identity) BuildSimpleAckResponseMessage(uuidToAck string) (fromServerMessage []byte, err error) {
 	var msg meowlib.FromServerMessage
 	msg.ServerPublicKey = id.ServerKp.Public
 	msg.UuidAck = uuidToAck
-	return &msg, nil
+	out, err := proto.Marshal(&msg)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
 }
 
 // AsymEncryptMessage prepares a message to send to a specific client contact