Not working with AutobahnPython client, any ideas?

[mriehl]

Hi,

I'm trying to use a variant of the simple router with the python autobahn client. The websocket connection upgrade works, but the simple router does not reply to the clients WAMP HELLO message:

2014-09-02 11:48:34+0200 [WampWebSocketClientProtocol,client] received HTTP status line in opening handshake : HTTP/1.1 101 Switching Protocols
2014-09-02 11:48:34+0200 [WampWebSocketClientProtocol,client] received HTTP headers in opening handshake : {u'connection': u'Upgrade', u'upgrade': u'websocket', u'sec-websocket-protocol': u'wamp.2.json.batched', u'sec-websocket-accept': u'zE8eNRgwuukgfNNzweN+kOauVCg='}
2014-09-02 11:48:34+0200 [WampWebSocketClientProtocol,client] TX WAMP HELLO Message (realm = realm1, roles = [<autobahn.wamp.role.RolePublisherFeatures instance at 0x7f73dda7cdd0>, <autobahn.wamp.role.RoleSubscriberFeatures instance at 0x7f73dda7ce18>, <autobahn.wamp.role.RoleCallerFeatures instance at 0x7f73dda7ce60>, <autobahn.wamp.role.RoleCalleeFeatures instance at 0x7f73dda7cea8>], authmethods = None, authid = None)
2014-09-02 11:48:34+0200 [WampWebSocketClientProtocol,client] TX Frame to 172.17.0.3:8080 : fin = True, rsv = 0, opcode = 1, mask = ebdc4880, length = 78, repeat_length = None, chopsize = None, sync = False, payload = [1,"realm1",{"roles":{"subscriber":{},"publisher":{},"caller":{},"callee":{}}}]
2014-09-02 11:48:34+0200 [WampWebSocketClientProtocol,client] TX Octets to 172.17.0.3:8080 : sync = False, octets = 81ceebdc4880b0ed64a292bd2cf4c9f033a299b324e598fe72fbc9af3de298bf3ae989b93aa2d1a735acc9ac3de287b53be88eae6aba90a164a288bd24ec8eae6aba90a164a288bd24ec8eb96aba90a135fdb6c4
# no response from server

Do you have an idea what the problem could be?

[mriehl]

Found the problem.

The AutobahnPython client asks for

[<<"wamp.2.json.batched">>,
 <<"wamp.2.json">>]

by default as a transfer protocol.

And then you have lines 51pp in erwa_ws_handler.erl with

  case lists:nth(1,Protocols) of
      ?WSMSGPACK ->
        Req2  = cowboy_req:set_resp_header(?SUBPROTHEADER,?WSMSGPACK,Req1),
        {ok,Req2,#state{enc=msgpack}};
      ?WSMSGPACK_BATCHED ->
        Req2  = cowboy_req:set_resp_header(?SUBPROTHEADER,?WSMSGPACK_BATCHED,Req1),
        {ok,Req2,#state{enc=msgpack_batched}};
      ?WSJSON ->
        Req2  = cowboy_req:set_resp_header(?SUBPROTHEADER,?WSJSON,Req1),
        {ok,Req2,#state{enc=json}};
      ?WSJSON_BATCHED ->
        Req2  = cowboy_req:set_resp_header(?SUBPROTHEADER,?WSJSON_BATCHED,Req1),
        {ok,Req2,#state{enc=json_batched}};
      _ ->
        {shutdown,Req1}

So this takes the first offered protocol (json batched) and tries to use that. Unfortunately the wamp part does not support batched json and simply ignores the requests.

[bwegh]

Hi, Thank you for the Feedback.

Which wamp Part does not support batched mode? Python Autobahn or Erwa? As Erwa should work, if not please let me know.

Cheers, Bas

[mriehl]

Hi @bwegh ,

actually erwa doesn't fully support batched json if I understand it correctly. The websocket_init code supports it (?WSJSON_BATCHED in erwa_ws_handler.erl:61) but then websocket_handle silently skips everything that is not json or msgpack encoded:

websocket_handle({text, Data}, Req, #state{enc=json}=State) ->
  {ok,NewState} = handle_wamp(Data,State),
  {ok,Req,NewState};
websocket_handle({binary, Data}, Req, #state{enc=msgpack}=State) ->
  {ok,NewState} = handle_wamp(Data,State),
  {ok,Req,NewState};
websocket_handle(_Data, Req, State) ->
  {ok, Req, State}.

As you can see this will only dispatch to handle_wamp if enc=json or enc=msgpack and ignore it otherwise.

[bwegh]

Hello @mriehl , could you please see if the latest version fixes this issue. I have right now little time for testing. Thanks a lot.

[mriehl]

Hi,

I tried the simple router example after pulling in e0edad1031c2bf83c65b28c7b5828704d6a04ce3. This now leads to another problem:

=ERROR REPORT==== 4-Sep-2014::13:01:54 ===
Error in process <0.194.0> on node 'simple_router@127.0.0.1' with exit value: {[{reason,badarg},{mfa,{erwa_ws_handler,websocket_handle,3}},{stacktrace,[{jsx_decoder,done,4,[{file,"src/jsx_decoder.erl"},{line,936}]},{erwa_protocol,'-deserialize/3-fun-0-',2,[{file,"src/erwa_protocol.erl"},{line,57}]},{lists... 

=ERROR REPORT==== 4-Sep-2014::13:01:54 ===
Ranch listener http had connection process started with cowboy_protocol:start_link/4 at <0.194.0> exit with reason: {[{reason,badarg},{mfa,{erwa_ws_handler,websocket_handle,3}},{stacktrace,[{jsx_decoder,done,4,[{file,"src/jsx_decoder.erl"},{line,936}]},{erwa_protocol,'-deserialize/3-fun-0-',2,[{file,"src/erwa_protocol.erl"},{line,57}]},{lists,foldl,3,[{file,"lists.erl"},{line,1261}]},{erwa_protocol,deserialize,3,[{file,"src/erwa_protocol.erl"},{line,57}]},{erwa_ws_handler,handle_wamp,2,[{file,"src/erwa_ws_handler.erl"},{line,105}]},{erwa_ws_handler,websocket_handle,3,[{file,"src/erwa_ws_handler.erl"},{line,73}]},{cowboy_websocket,handler_call,7,[{file,"src/cowboy_websocket.erl"},{line,589}]},{cowboy_protocol,execute,4,[{file,"src/cowboy_protocol.erl"},{line,435}]}]},{msg,{text,<<91,49,44,34,121,97,100,116,34,44,123,34,114,111,108,101,115,34,58,123,34,115,117,98,115,99,114,105,98,101,114,34,58,123,125,44,34,112,117,98,108,105,115,104,101,114,34,58,123,125,44,34,99,97,108,108,101,114,34,58,123,125,44,34,99,97,108,108,101,101,34,58,123,125,125,125,93,24>>}},{req,[{socket,#Port<0.814>},{transport,ranch_tcp},{connection,keepalive},{pid,<0.194.0>},{method,<<"GET">>},{version,'HTTP/1.1'},{peer,{{172,17,42,1},39456}},{host,<<"node1">>},{host_info,undefined},{port,8080},{path,<<"/wamp">>},{path_info,undefined},{qs,<<>>},{qs_vals,undefined},{bindings,[]},{headers,[{<<"user-agent">>,<<"AutobahnPython/0.8.15">>},{<<"host">>,<<"node1:8080">>},{<<"upgrade">>,<<"WebSocket">>},{<<"connection">>,<<"Upgrade">>},{<<"pragma">>,<<"no-cache">>},{<<"cache-control">>,<<"no-cache">>},{<<"sec-websocket-key">>,<<"1HfkAh9zkC0ievIgAfMQiQ==">>},{<<"sec-websocket-protocol">>,<<"wamp.2.json.batched">>},{<<"sec-websocket-version">>,<<"13">>}]},{p_headers,[{<<"sec-websocket-protocol">>,[<<"wamp.2.json.batched">>]},{<<"upgrade">>,[<<"websocket">>]},{<<"connection">>,[<<"upgrade">>]}]},{cookies,undefined},{meta,[{websocket_version,13},{websocket_compress,false}]},{body_state,waiting},{buffer,<<>>},{multipart,undefined},{resp_compress,false},{resp_state,done},{resp_headers,[]},{resp_body,<<>>},{onresponse,undefined}]},{state,{state,json_batched,undefined,<<>>}}],[{cowboy_protocol,execute,4,[{file,"src/cowboy_protocol.erl"},{line,435}]}]}

[bwegh]

Hi @mriehl ,

It is working for me with a javascript websocket client using json, the test checks if a batched is forced to json and it is. Could you please test with your client and confirm this.

Thanks for your feedback, Bas

[mriehl]

Hi @bwegh ,

I pulled in your changes and it works like a charm now. As long as the client supports json this is what the server forces. Thanks a lot for your help and for your work on erwa!

[bwegh]

Great to hear it is working for you. Yes at the moment erwa is enforcing json or msgpack in non batched mode.

I already opened an enhacement issue to implement the batched versions

Cheers, Bas