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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/manual/cowboy_websocket.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/manual/cowboy_websocket.asciidoc')
-rw-r--r--doc/src/manual/cowboy_websocket.asciidoc66
1 files changed, 38 insertions, 28 deletions
diff --git a/doc/src/manual/cowboy_websocket.asciidoc b/doc/src/manual/cowboy_websocket.asciidoc
index 73f5e72..b728edf 100644
--- a/doc/src/manual/cowboy_websocket.asciidoc
+++ b/doc/src/manual/cowboy_websocket.asciidoc
@@ -10,31 +10,6 @@ The module `cowboy_websocket` implements Websocket
as a Ranch protocol. It also defines a callback interface
for handling Websocket connections.
-== Options
-
-[source,erlang]
-----
-opts() :: #{
- websocket_compress := boolean()
-}
-----
-
-Configuration for the Websocket protocol.
-
-This configuration is passed to Cowboy when starting listeners
-using `cowboy:start_clear/4` or `cowboy:start_tls/4` functions.
-
-It can be updated without restarting listeners using the
-Ranch functions `ranch:get_protocol_options/1` and
-`ranch:set_protocol_options/2`.
-
-The default value is given next to the option name:
-
-websocket_compress (false)::
- Whether to enable the Websocket frame compression
- extension. Frames will only be compressed for the
- clients that support this extension.
-
== Callbacks
Websocket handlers must implement the following callback
@@ -44,9 +19,7 @@ interface:
----
init(Req, State)
-> {cowboy_websocket, Req, State}
- | {cowboy_websocket, Req, State, hibernate}
- | {cowboy_websocket, Req, State, timeout()}
- | {cowboy_websocket, Req, State, timeout(), hibernate}
+ | {cowboy_websocket, Req, State, Opts}
websocket_init(State) -> CallResult %% optional
websocket_handle(InFrame, State) -> CallResult
@@ -56,6 +29,7 @@ terminate(Reason, undefined, State) -> ok %% optional
Req :: cowboy_req:req()
State :: any()
+Opts :: cowboy_websocket:opts()
InFrame :: {text | binary | ping | pong, binary()}
OutFrame :: cow_ws:frame()
Info :: any()
@@ -152,6 +126,42 @@ timeout::
{error, Reason}::
A socket error ocurred.
+== Types
+
+=== opts()
+
+[source,erlang]
+----
+opts() :: #{
+ compress => boolean(),
+ idle_timeout => timeout()
+}
+----
+
+Websocket handler options.
+
+This configuration is passed to Cowboy from the `init/2`
+function:
+
+[source,erlang]
+----
+init(Req, State) ->
+ Opts = #{compress => true},
+ {cowboy_websocket, Req, State, Opts}.
+----
+
+The default value is given next to the option name:
+
+compress (false)::
+ Whether to enable the Websocket frame compression
+ extension. Frames will only be compressed for the
+ clients that support this extension.
+
+idle_timeout (60000)::
+ Time in milliseconds that Cowboy will keep the
+ connection open without receiving anything from
+ the client.
+
== Changelog
* *2.0*: The Req object is no longer passed to Websocket callbacks.