# Erlang Websocket Client
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## Existing features
1. Client to Server Masking
2. OTP compliant
3. Callback-driven behaviour
3. Handshake validation
4. TCP and SSL support
5. Handling of text, binary, ping, pong, and close frames
6. Handling of continuation frames
7. Automated ping/pong and keepalive
## Usage
For basic usage, see `examples/sample_ws_handler.erl`:
```erlang
-module(sample_ws_handler).
-behaviour(websocket_client).
-export([
start_link/0,
init/1,
onconnect/2,
ondisconnect/2,
websocket_handle/3,
websocket_info/3,
websocket_terminate/3
]).
start_link() ->
crypto:start(),
ssl:start(),
websocket_client:start_link("wss://echo.websocket.org", ?MODULE, []).
init([]) ->
{once, 2}.
onconnect(_WSReq, State) ->
websocket_client:cast(self(), {text, <<"message 1">>}),
{ok, State}.
ondisconnect({remote, closed}, State) ->
{reconnect, State}.
websocket_handle({pong, _}, _ConnState, State) ->
{ok, State};
websocket_handle({text, Msg}, _ConnState, 5) ->
io:format("Received msg ~p~n", [Msg]),
{close, <<>>, "done"};
websocket_handle({text, Msg}, _ConnState, State) ->
io:format("Received msg ~p~n", [Msg]),
timer:sleep(1000),
BinInt = list_to_binary(integer_to_list(State)),
{reply, {text, <<"hello, this is message #", BinInt/binary >>}, State + 1}.
websocket_info(start, _ConnState, State) ->
{reply, {text, <<"erlang message received">>}, State}.
websocket_terminate(Reason, _ConnState, State) ->
io:format("Websocket closed in state ~p wih reason ~p~n",
[State, Reason]),
ok.
```
The above code will send messages to the echo server that count up
from 1 through 4. It will also print all replies from the server:
```
Received msg <<"this is message 1">>
Received msg <<"hello, this is message #2">>
Received msg <<"hello, this is message #3">>
Received msg <<"hello, this is message #4">>
```
This client implements a cowboy like `websocket_client_handler` to
interact with a websocket server. Currently, it can connect via tcp or
ssl via the `ws` and `wss` protocols. It can also send and receive
contiguous text or binary websocket frames.
## TODO
The client has been significantly reworked, now backed by `gen_fsm`. There may still be bugs.
Please report them.
1. Stop using `verify_none` by default
2. Add more complete testing - preferably based on / using Autobahn.