wamp_service

TODO: still needs generalization and refactoring especially opts.

A boilerplate WAMP micro service infrastructure for developing basic micro service with WAMP support. This micro service registers to procedures: com.example.add2 and com.leapsight.echo. The first one is intended to be used with crossbar example application.

This allows register procedures and subscriptions in a declarative way and abstract actual wamp complexity from service implementation. If more complex feature of the WAMP protocol is needed it should be handled by the service.

Configuration

The micro service has several configurations in sys.config:

 %% service conf
 {wamp_service,
  [
   {callee_dispatcher,
    [
     %% wamp opts
     {hostname, "localhost"},
     {port, 18082},
     {realm, <<"com.magenta.test">>},
     {encoding, json},
     {reconnect, true},
     %% service callbacks
     {callbacks,
      [
       {procedure, <<"com.example.add2">>, {wamp_service_example, add}},
       {procedure, <<"com.example.echo">>, {wamp_service_example, echo}},
       {procedure, <<"com.example.multiple">>, {wamp_service_example, multiple_results}},
       {procedure, <<"com.example.circular">>, {wamp_service_example, circular}},
       {procedure, <<"com.example.circular_service_error">>, {wamp_service_example, circular_service_error}},
       {procedure, <<"com.example.unknown_error">>, {wamp_service_example, unknown_error}},
       {procedure, <<"com.example.notfound_error">>, {wamp_service_example, notfound_error}},
       {procedure, <<"com.example.validation_error">>, {wamp_service_example, validation_error}},
       {procedure, <<"com.example.service_error">>, {wamp_service_example, service_error}},
       {procedure, <<"com.example.authorization_error">>, {wamp_service_example, authorization_error}},
       {procedure, <<"com.example.timeout">>, {wamp_service_example, timeout}},
       {subscription, <<"com.example.onhello">>, {wamp_service_example, onhello}},
       {subscription, <<"com.example.onadd">>, {wamp_service_example, onadd}}
      ]}
    ]
   },
   {caller_service,
    [
     %% wamp opts
     {hostname, "localhost"},
     {port, 18082},
     {realm, <<"com.magenta.test">>},
     {encoding, json},
     {reconnect, true}
    ]
   }
  ]},

The worker args are the usual connection options plus service callbacks definitions, for each callback it will be added a procedure or subscription with the given URI and the handler given by the tuple `{module, function}. Finally the reconnect options are the attempts to retry to reconnect and initial exponential backoff.

Build

$ rebar3 compile

Test

In order to test you must start a wamp broker, for example bondy for testing.

Or using docker

$ docker run --rm -it -p 18080:18080 -p 18081:18081 -p 18082:18082 --name bondy registry.gitlab.com/leapsight/bondy:latest

Start the erlang shell:

$ rebar3 auto

In the Erlang shell start the micro service:

application:start(wamp_service).

To test the micro service and published procedures on the same shell or a new one:

wamp_service:call(<<"com.example.echo">>, ["Hello wamp!"], #{<<"security">> => #{<<"groups">> => [<<"admin">>]}}).
wamp_service:call(<<"com.example.add2">>, [1, 1], #{}).
wamp_service:call(<<"com.example.error">>, [], #{}). % error test
wamp_service:publish(<<"com.example.onhello">>, [<<"Hello wamp!">>], #{}).
wamp_service:publish(<<"com.example.onadd">>, [1, 2], #{}).

The call function return either the result or an error result, see maybe_call for variants automatically raising an error().

You can also register or unregister procedure or subscription dynamically in the following way:

wamp_service:unregister(<<"com.example.echo">>).
wamp_service:register(procedure, <<"com.example.echo">>, fun(X, _Opts) -> X end).

Developing a new Service

In order to create a new service you should use the rebar3 template basic_service_template.

Volume test

application:start(wamp_service).
lists:foreach(fun(N) ->
                spawn(fun() ->
                        T1 = erlang:system_time(millisecond),
                        N1 = N + 1,
                        {ok, N1} = wamp_service:call(<<"com.example.add2">>, [N, 1], #{<<"trace_id">> => N}),
                        io:format("~p -> ~p~n", [N, erlang:system_time(millisecond) - T1])
                      end)
             end, lists:seq(1, 1000)).