diff --git a/docs/conf-sessions.rst b/docs/conf-sessions.rst
index 09a978694..dea5a351b 100644
--- a/docs/conf-sessions.rst
+++ b/docs/conf-sessions.rst
@@ -76,6 +76,12 @@ the global lock (the value can be set using the option ``<option
 name="global_number" value ="XXX"/>`` and by setting `maxnumber=N` in
 ``<arrivalphase>``).
 
+**Since version 1.5.2**, you can wait for a 'bidi' ack. If your protocol is bidirectionnal (e.g. xmpp, websocket, ...), you can wait until the server sends some data, and the code that handle this data exits the ``think`` state.
+
+.. code-block:: xml
+
+   <thinktime value="wait_bidi"></thinktime> -
+
 HTTP
 ^^^^
 
diff --git a/examples/jabber_starttls.xml.in b/examples/jabber_starttls.xml.in
index 8e46ac69c..35ef4c008 100644
--- a/examples/jabber_starttls.xml.in
+++ b/examples/jabber_starttls.xml.in
@@ -50,9 +50,10 @@
 
     <thinktime value="5"></thinktime>
 
-    <request> <jabber type="starttls" ack="no_ack" /> </request>
-    <thinktime value="3"></thinktime>
+    <request> <jabber type="starttls" ack="bidi_ack" /> </request>
     <request> <jabber type="connect" ack="local"></jabber> </request>
+    <!-- needed -->
+    <thinktime value="3"></thinktime>
 
    <transaction name="authenticate">
      <request> <jabber type="auth_sasl" ack="local"></jabber></request>
diff --git a/src/tsung/ts_amqp.erl b/src/tsung/ts_amqp.erl
index 3ae0c17b2..dd67181ab 100644
--- a/src/tsung/ts_amqp.erl
+++ b/src/tsung/ts_amqp.erl
@@ -263,7 +263,7 @@ parse_bidi(<<>>, State=#state_rcv{acc = [], session = AMQPSession}) ->
     AckBuf = AMQPSession#amqp_session.ack_buf,
     NewAMQPSession = AMQPSession#amqp_session{ack_buf = <<>>},
     ?DebugF("ack buf: ~p~n", [AckBuf]),
-    {confirm_ack_buf(AckBuf), State#state_rcv{session = NewAMQPSession}};
+    {confirm_ack_buf(AckBuf), State#state_rcv{session = NewAMQPSession},think};
 parse_bidi(Data, State=#state_rcv{acc = [], session = AMQPSession}) ->
     ?DebugF("parse bidi data: ~p ~p~n", [size(Data), Data]),
     Protocol = AMQPSession#amqp_session.protocol,
@@ -271,7 +271,7 @@ parse_bidi(Data, State=#state_rcv{acc = [], session = AMQPSession}) ->
     case decode_frame(Protocol, Data) of
         {error, _Reason} ->
             ?DebugF("decode error: ~p~n", [_Reason]),
-            {nodata, State};
+            {nodata, State, think};
         {ok, heartbeat, Left} ->
             ?DebugF("receive bidi: ~p~n", [heartbeat]),
             HB = list_to_binary(rabbit_binary_generator:build_heartbeat_frame()),
@@ -286,7 +286,7 @@ parse_bidi(Data, State=#state_rcv{acc = [], session = AMQPSession}) ->
             parse_bidi(Left, State#state_rcv{session = NewAMQPSession});
         {incomplete, Left} ->
             ?DebugF("incomplete frame: ~p~n", [Left]),
-            {confirm_ack_buf(AckBuf), State#state_rcv{acc = Left}}
+            {confirm_ack_buf(AckBuf), State#state_rcv{acc = Left},think}
     end;
 parse_bidi(Data, State=#state_rcv{acc = Acc, datasize = DataSize,
                                   session = AMQPSession}) ->
diff --git a/src/tsung/ts_client.erl b/src/tsung/ts_client.erl
index 1d3a33941..26eabd731 100644
--- a/src/tsung/ts_client.erl
+++ b/src/tsung/ts_client.erl
@@ -297,20 +297,25 @@ handle_info2({gen_ts_transport, Socket, Data}, think,State=#state_rcv{
     ts_mon:add({ sum, size_rcv, size(Data)}),
     Proto = State#state_rcv.protocol,
     ?LOG("Data received from socket (bidi) in state think~n",?INFO),
-    NewState = case Type:parse_bidi(Data, State) of
-                   {nodata, State2} ->
+    {NextAction, NewState} = case Type:parse_bidi(Data, State) of
+                   {nodata, State2, Action} ->
                        ?LOG("Bidi: no data ~n",?DEB),
                        ts_mon:add({count, async_unknown_data_rcv}),
-                       State2;
-                   {Data2, State2} ->
+                       {Action, State2};
+                   {Data2, State2, Action} ->
                        ts_mon:add([{ sum, size_sent, size(Data2)},{count, async_data_sent}]),
                        ts_mon:sendmes({State#state_rcv.dump, self(), Data2}),
                        ?LOG("Bidi: send data back to server~n",?DEB),
                        send(Proto,Socket,Data2,Host,Port), %FIXME: handle errors ?
-                       State2
+                       {Action, State2}
                end,
     NewSocket = (NewState#state_rcv.protocol):set_opts(NewState#state_rcv.socket, [{active, once}]),
-    {next_state, think, NewState#state_rcv{socket=NewSocket}};
+    case NextAction of
+        think ->
+            {next_state, think, NewState#state_rcv{socket=NewSocket}};
+        continue  ->
+            handle_next_action(NewState#state_rcv{socket=NewSocket})
+    end;
 % bidi is false, but parse is also false: continue even if we get data
 handle_info2({gen_ts_transport, Socket, Data}, think, State = #state_rcv{request=Req} )
   when (Req#ts_request.ack /= parse) ->
@@ -823,6 +828,8 @@ handle_next_request(Request, State) ->
                                                send_timestamp= Now,
                                                timestamp= Now },
                     case Request#ts_request.ack of
+                        bidi_ack ->
+                            {next_state, think, NewState};
                         no_ack ->
                             {PTimeStamp, _} = update_stats_noack(NewState),
                             handle_next_action(NewState#state_rcv{ack_done=true, page_timestamp=PTimeStamp});
@@ -1163,8 +1170,7 @@ handle_data_msg(closed,State) ->
     {State,[]};
 
 %% ack = global
-handle_data_msg(Data,State=#state_rcv{request=Req,datasize=OldSize})
-  when Req#ts_request.ack==global ->
+handle_data_msg(Data,State=#state_rcv{request=Req,datasize=OldSize}) when Req#ts_request.ack==global ->
     %% FIXME: we do not report size now (but after receiving the
     %% global ack), the size stats may be not very accurate.
     %% FIXME: should we set buffer and parse for dynvars ?
diff --git a/src/tsung/ts_jabber.erl b/src/tsung/ts_jabber.erl
index 510878bdb..5dabeb863 100644
--- a/src/tsung/ts_jabber.erl
+++ b/src/tsung/ts_jabber.erl
@@ -176,7 +176,7 @@ parse_bidi(Data,  State) ->
         _Else ->
             Acc
         end
-    end, {nodata, State}, BidiElements).
+    end, {nodata, State, think}, BidiElements).
 
 presence_bidi(RcvdXml, State)->
     {match,SubMatches} = re:run(RcvdXml,"<presence[^>]*subscribe[\"\'][^>]*>",[global]),
@@ -191,14 +191,14 @@ message_bidi(RcvdXml, State) ->
             Mega = list_to_integer(MegaS),
             Secs = list_to_integer(SecsS),
             Micro = list_to_integer(MicroS),
-            Latency = timer:now_diff(erlang:now(), {Mega, Secs, Micro}),
+            Latency = timer:now_diff(?NOW, {Mega, Secs, Micro}),
             ts_mon:add({ sample, xmpp_msg_latency, Latency / 1000});
         _ ->
             ignore
     end,
-    {nodata, State}.
+    {nodata, State, think}.
 
-starttls_bidi(_RcvdXml, #state_rcv{socket= Socket}=State)->
+starttls_bidi(_RcvdXml, #state_rcv{socket= Socket, send_timestamp=SendTime}=State)->
     ssl:start(),
     Req = subst(State#state_rcv.request#ts_request.param, State#state_rcv.dynvars),
     Opt = lists:filter(fun({_,V}) -> V /= undefined end, 
@@ -208,7 +208,9 @@ starttls_bidi(_RcvdXml, #state_rcv{socket= Socket}=State)->
                        {cacertfile,Req#jabber.cacertfile}]),
     {ok, SSL} = ts_ssl:connect(Socket, Opt),
     ?LOGF("Upgrading to TLS : ~p",[SSL],?INFO),
-    {nodata, State#state_rcv{socket=SSL,protocol=ts_ssl}}.
+    Latency = ts_utils:elapsed(SendTime, ?NOW),
+    ts_mon:add({ sample, xmpp_starttls, Latency}),
+    {nodata, State#state_rcv{socket=SSL,protocol=ts_ssl}, continue}.
 
 %%----------------------------------------------------------------------
 %% Function: bidi_resp/4
@@ -219,6 +221,7 @@ starttls_bidi(_RcvdXml, #state_rcv{socket= Socket}=State)->
 %%          State (record)
 %% Returns:    Data (binary)
 %%             NewState (record)
+%%             think|continue
 %%----------------------------------------------------------------------
 %% subscribed: Complete a pending subscription request
 bidi_resp(subscribed,RcvdXml,SubMatches,State) ->
@@ -238,10 +241,10 @@ bidi_resp(subscribed,RcvdXml,SubMatches,State) ->
     end,"",SubMatches),
     case lists:flatten(JoinedXml) of
         "" ->
-            {nodata,State};
+            {nodata,State, think};
         _ ->
             ?LOGF("RESPONSE TO SEND : ~s~n",[JoinedXml],?DEB),
-            {list_to_binary(JoinedXml),State}
+            {list_to_binary(JoinedXml),State, think}
     end.
 
 %%
diff --git a/src/tsung/ts_jabber_common.erl b/src/tsung/ts_jabber_common.erl
index fa0d963ac..694d323ad 100644
--- a/src/tsung/ts_jabber_common.erl
+++ b/src/tsung/ts_jabber_common.erl
@@ -451,7 +451,7 @@ auth_sasl_bind(#jabber{username=Name,passwd=Passwd,domain=Domain, resource=Resou
 %%----------------------------------------------------------------------
 auth_sasl_bind(_Username, _Passwd, _Domain, Resource) ->
  list_to_binary(["<iq type='set' id='",ts_msg_server:get_id(list),
-                 "' ><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>",
+                 "'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>",
                  "<resource>",Resource,"</resource>",
                  "</bind></iq>"]).
 
@@ -468,7 +468,7 @@ auth_sasl_session(#jabber{username=Name,passwd=Passwd,domain=Domain})->
 %%----------------------------------------------------------------------
 auth_sasl_session(_Username, _Passwd, _Domain) ->
  list_to_binary(["<iq type='set' id='",ts_msg_server:get_id(list),
-"' ><session xmlns='urn:ietf:params:xml:ns:xmpp-session' /></iq>"]).
+"'><session xmlns='urn:ietf:params:xml:ns:xmpp-session'/></iq>"]).
 
 %%----------------------------------------------------------------------
 %% Func: registration/1
diff --git a/src/tsung/ts_ldap.erl b/src/tsung/ts_ldap.erl
index 90129b77d..3c0e0d25d 100644
--- a/src/tsung/ts_ldap.erl
+++ b/src/tsung/ts_ldap.erl
@@ -80,7 +80,7 @@ dump(A,B)->
     ts_plugin:dump(A,B).
 
 parse_bidi(A, B) ->
-    ts_plugin:dump(A,B).
+    ts_plugin:parse_bidi(A,B).
 
 %%----------------------------------------------------------------------
 %% Function: parse/2
diff --git a/src/tsung/ts_mqtt.erl b/src/tsung/ts_mqtt.erl
index 770c2e65c..4448e959b 100644
--- a/src/tsung/ts_mqtt.erl
+++ b/src/tsung/ts_mqtt.erl
@@ -215,7 +215,7 @@ parse_bidi(<<>>, State=#state_rcv{acc = [], session = MqttSession}) ->
     end,
     NewMqttSession = MqttSession#mqtt_session{ack_buf = <<>>},
     ?DebugF("ack buf: ~p~n", [AckBuf]),
-    {Ack, State#state_rcv{session = NewMqttSession}};
+    {Ack, State#state_rcv{session = NewMqttSession}, think};
 parse_bidi(Data, State=#state_rcv{acc = [], session = MqttSession}) ->
     AckBuf = MqttSession#mqtt_session.ack_buf,
     case mqtt_frame:decode(Data) of
@@ -239,7 +239,7 @@ parse_bidi(Data, State=#state_rcv{acc = [], session = MqttSession}) ->
                     [mqtt_frame:command_for_type(_Type), _MqttMsg]),
             parse_bidi(Left, State);
         more ->
-            {nodata, State#state_rcv{acc = Data}}
+            {nodata, State#state_rcv{acc = Data},think}
     end;
 parse_bidi(Data, State=#state_rcv{acc = Acc, datasize = DataSize}) ->
     NewSize = DataSize + size(Data),
diff --git a/src/tsung/ts_plugin.erl b/src/tsung/ts_plugin.erl
index c3abe954f..647241e07 100644
--- a/src/tsung/ts_plugin.erl
+++ b/src/tsung/ts_plugin.erl
@@ -50,10 +50,12 @@ dump(_Type,_Data) ->
     ok.
 
 %% @spec parse_bidi(Data::binary(),State::record(state_rcv)) ->
-%%   {NewData::binary()|nodata, NewState::record(state_rcv)}
+%%   {NewData::binary()|nodata, NewState::record(state_rcv), think|continue}
 %% @doc Parse a block of data from the server. No reply will be sent
 %% if the return value is nodata, otherwise the Data binary will be
-%% sent back to the server immediately.
+%% sent back to the server immediately. If the last argument is
+%% 'think', it will continue to wait; if it's 'continue', it will
+%% handle the next action (request, thinktime, ...)
 %% @end
 parse_bidi(_Data, State) ->
-    {nodata, State}.
+    {nodata, State, think}.
diff --git a/src/tsung_controller/ts_config.erl b/src/tsung_controller/ts_config.erl
index 410979718..862be4952 100644
--- a/src/tsung_controller/ts_config.erl
+++ b/src/tsung_controller/ts_config.erl
@@ -926,6 +926,8 @@ parse(Element = #xmlElement{name=option, attributes=Attrs},
 parse(Element = #xmlElement{name=thinktime, attributes=Attrs},
       Conf = #config{curid=Id, session_tab = Tab, sessions = [CurS |_]}) ->
     {RT,T} = case getAttr(Attrs, value)  of
+            "wait_bidi" ->
+                {infinity, infinity};
             "wait_global" ->
                 {wait_global,infinity};
             "%%"++Tail -> % dynamic thinktime
diff --git a/tsung-1.0.dtd b/tsung-1.0.dtd
index 9afe1889a..7c1bd5c2d 100644
--- a/tsung-1.0.dtd
+++ b/tsung-1.0.dtd
@@ -257,7 +257,7 @@ repeat | if | change_type | foreach | set_option | interaction )*>
 
 <!ELEMENT jabber (xmpp_authenticate?) >
 <!ATTLIST jabber
-    ack         (global | local | no_ack | parse) #REQUIRED
+    ack         (global | local | no_ack | parse | bidi_ack) #REQUIRED
     destination (online | offline | random | unique | previous) "random"
     id          NMTOKEN #IMPLIED
     size        NMTOKEN "0"