From 9a03e5087e483119cf6965fa848c84d72282a0b6 Mon Sep 17 00:00:00 2001
From: Badlop <badlop@process-one.net>
Date: Mon, 26 Nov 2007 10:15:18 +0000
Subject: [PATCH] * src/mod_echo.erl: Example function that demonstrates how to
 receive XMPP packets using Erlang's message passing mechanism (EJAB-247).

SVN Revision: 980
---
 ChangeLog        |  2 ++
 src/mod_echo.erl | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index c6a2b8e61..4558b7b9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2007-11-26  Badlop  <badlop@process-one.net>
 
+	* src/mod_echo.erl: Example function that demonstrates how to receive XMPP packets using Erlang's message passing mechanism (EJAB-247).
+
 	* src/ejabberdctl.template: Removed bashisms (EJAB-399). Set environment variables instead of passing parameters when calling erl (EJAB-421). Write erl_crash.dump in the log/ directory, with unique filename (EJAB-433).
 
 	* src/ejabberd_ctl.erl: Improvements in the help messages (EJAB-399).
diff --git a/src/mod_echo.erl b/src/mod_echo.erl
index b75929958..050677304 100644
--- a/src/mod_echo.erl
+++ b/src/mod_echo.erl
@@ -102,6 +102,7 @@ handle_info({route, From, To, Packet}, State) ->
 		"" -> jlib:make_error_reply(Packet, ?ERR_BAD_REQUEST);
 		_ -> Packet
 	end,
+    do_client_version(To, From),
     ejabberd_router:route(To, From, Packet2),
     {noreply, State};
 handle_info(_Info, State) ->
@@ -128,3 +129,50 @@ code_change(_OldVsn, State, _Extra) ->
 %%--------------------------------------------------------------------
 %%% Internal functions
 %%--------------------------------------------------------------------
+
+%% ejabberd provides a method to receive XMPP packets using Erlang's 
+%% message passing mechanism. 
+%%
+%% The packets received by ejabberd are sent
+%% to the local destination process by sending an Erlang message.
+%% This means that you can receive XMPP stanzas in an Erlang process 
+%% using Erlang's Receive, as long as this process is registered in
+%% ejabberd as the process which handles the destination JID.
+%%
+%% This example function is called when a client queries the echo service.
+%% This function then sends a query to the client, and waits 5 seconds to
+%% receive an answer. The answer will only be accepted if it was sent
+%% using exactly the same JID. We add a (mostly) random resource to
+%% try to guarantee that the received response matches the request sent.
+%% Finally, the received response is printed in the ejabberd log file.
+do_client_version(From, To) ->
+    ToS = jlib:jid_to_string(To),
+    %% It is important to identify this process and packet
+    Random_resource = integer_to_list(random:uniform(100000)),
+    From2 = From#jid{resource = Random_resource,
+		     lresource = Random_resource},
+    
+    %% Build an iq:query request
+    Packet = {xmlelement, "iq",
+	      [{"to", ToS}, {"type", "get"}],
+	      [{xmlelement, "query", [{"xmlns", ?NS_VERSION}], []}]},
+    
+    %% Send the request 
+    ejabberd_router:route(From2, To, Packet), 
+    
+    %% Wait to receive the response
+    %% It is very important to only accept a packet which is the 
+    %% response to the request that he sent
+    Els = receive {route, To, From2, IQ} ->
+		  {xmlelement, "query", _, List} = xml:get_subtag(IQ, "query"),
+		  List
+	  after 5000 -> % Timeout in miliseconds: 5 seconds
+		  []
+	  end,
+    Values = [{Name, Value} || {xmlelement,Name,[],[{xmlcdata,Value}]} <- Els],
+    
+    %% Print in log
+    Values_string1 = [io_lib:format("~n~s: ~p", [N, V]) || {N, V} <- Values],
+    Values_string2 = lists:concat(Values_string1),
+    ?INFO_MSG("Information of the client: ~s~s", [ToS, Values_string2]).
+