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authorLoïc Hoguin <[email protected]>2017-02-18 18:26:20 +0100
committerLoïc Hoguin <[email protected]>2017-02-18 18:26:20 +0100
commita45813c60f0f983a24ea29d491b37f0590fdd087 (patch)
treec7e741ac4a684b365e70f7ff73d0c4b6e34232a7 /doc/src/guide/ws_handlers.asciidoc
parent80f8cda7ff8fe6a575b4c2eaedd8451acf4fcef3 (diff)
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Allow passing options to sub protocols
Before this commit we had an issue where configuring a Websocket connection was simply not possible without doing magic, adding callbacks or extra return values. The init/2 function only allowed setting hibernate and timeout options. After this commit, when switching to a different type of handler you can either return {module, Req, State} or {module, Req, State, Opts} where Opts is any value (as far as the sub protocol interface is concerned) and is ultimately checked by the custom handlers. A large protocol like Websocket would accept only a map there, with many different options, while a small interface like loop handlers would allow passing hibernate and nothing else. For Websocket, hibernate must be set from the websocket_init/1 callback, because init/2 executes in a separate process. Sub protocols now have two callbacks: one with the Opts value, one without. The loop handler code was largely reworked and simplified. It does not need to manage a timeout or read from the socket anymore, it's the job of the protocol code. A lot of unnecessary stuff was therefore removed. Websocket compression must now be enabled from the handler options instead of per listener. This means that a project can have two separate Websocket handlers with different options. Compression is still disabled by default, and the idle_timeout value was changed from inifnity to 60000 (60 seconds), as that's safer and is also a good value for mobile devices.
Diffstat (limited to 'doc/src/guide/ws_handlers.asciidoc')
-rw-r--r--doc/src/guide/ws_handlers.asciidoc9
1 files changed, 5 insertions, 4 deletions
diff --git a/doc/src/guide/ws_handlers.asciidoc b/doc/src/guide/ws_handlers.asciidoc
index 011aa31..2c38b87 100644
--- a/doc/src/guide/ws_handlers.asciidoc
+++ b/doc/src/guide/ws_handlers.asciidoc
@@ -60,13 +60,13 @@ be:
init(Req, State) ->
case cowboy_req:parse_header(<<"sec-websocket-protocol">>, Req) of
undefined ->
- {ok, Req, State};
+ {cowboy_websocket, Req, State};
Subprotocols ->
case lists:keymember(<<"mqtt">>, 1, Subprotocols) of
true ->
Req2 = cowboy_req:set_resp_header(<<"sec-websocket-protocol">>,
<<"mqtt">>, Req),
- {ok, Req2, State};
+ {cowboy_websocket, Req2, State};
false ->
{stop, Req, State}
end
@@ -210,12 +210,13 @@ than needed.
The `init/2` callback can set the timeout to be used
for the connection. For example, this would make Cowboy
-close connections idle for more than 60 seconds:
+close connections idle for more than 30 seconds:
[source,erlang]
----
init(Req, State) ->
- {cowboy_websocket, Req, State, 60000}.
+ {cowboy_websocket, Req, State, #{
+ idle_timeout => 30000}}.
----
This value cannot be changed once it is set. It defaults to