Author: Tristan Sloughter tristan.sloughter@gmail.com website: http://blog.erlware.org
Version: 0.0.4
- Dependencies
$ ./rebar get-deps- Compile
$ ./rebar compile- Test
$ erl +K true +A30 -pa ebin -env ERL_LIBS lib:deps -config config/sys.config
Erlang R15B03 (erts-5.9.3.1) [source] [smp:4:4] [async-threads:30] [hipe] [kernel-poll:true]
Eshell V5.9.3.1 (abort with ^G)
1> epubnub_app:start_deps().
ok
2> epubnub:publish(<<"hello_world">>, <<"hello">>).
{[1,<<"Sent">>,<<"13612809348896246">>],
{client,hackney_tcp_transport,"pubsub.pubnub.com",80,netloc,
[],#Port<0.2131>,infinity,false,5,false,nil,undefined,
connected,done,nil,normal,#Fun<hackney_request.send.2>,done,
4096,<<>>,
{1,1},
30,nil,<<"keep-ali"...>>,<<"text"...>>}}src/epn_example_client has a simple example of a gen_server subscribing to a channel. The init function takes an EPN record, created with epubsub:new() in start_link and requests to subscribe to the "hello_world" channel and sends its PID with the self() function so new messages are sent to this process.
init([EPN]) ->
{ok, PID} = epubnub_sup:subscribe(EPN, <<"hello_world">>, self()),
{ok, #state{pid=PID}}.
Since currently the subscribe loop sends the message with the bang (!) the gen_server will handle the new message in handle_info. The example simply prints out the contents of the message:
handle_info({message, Message}, State) ->
io:format("~p~n", [Message]),
{noreply, State}.
To unscribe we call the module stop function that sends an async stop message to the process. The handle_cast function handles this message and return stop telling the gen_server to go to terminate. In terminate we take the PID of the subscribed process to the epubnub unsubscribe function which sends it a terminate message and it exits.
stop() ->
gen_server:cast(?SERVER, stop).
handle_cast(stop, State) ->
{stop, normal, State}.
terminate(_Reason, #state{pid=PID}) ->
epubnub:unsubscribe(PID),
ok.