This change simplifies a little more the sub protocols mechanism.
Aliases have been removed. The renaming of loop handlers as long
polling handlers has been reverted.
Plain HTTP handlers now simply do their work in the init/2
callback. There is no specific code for them.
Loop handlers now follow the same return value as Websocket,
they use ok to continue and shutdown to stop.
Terminate reasons for all handler types have been documented.
The terminate callback is now appropriately called in all cases
(or should be).
Behaviors for all handler types have been moved in the module
that implement them. This means that cowboy_handler replaces
the cowboy_http_handler behavior, and similarly cowboy_loop
replaces cowboy_loop_handler, cowboy_websocket replaces
cowboy_websocket_handler. Finally cowboy_rest now has the
start of a behavior in it and will have the full list of
optional callbacks defined once Erlang 18.0 gets released.
The guide has been reorganized and should be easier to follow.
This set of changes is the first step to simplify the
writing of handlers, by removing some extraneous
callbacks and making others optional.
init/3 is now init/2, its first argument being removed.
rest_init/2 and rest_terminate/2 have been removed.
websocket_init/3 and websocket_terminate/3 have been removed.
terminate/3 is now optional. It is called regardless of
the type of handler, including rest and websocket.
The return value of init/2 changed. It now returns
{Mod, Req, Opts} with Mod being either one of the four
handler type or a custom module. It can also return extra
timeout and hibernate options.
The signature for sub protocols has changed, they now
receive these extra timeout and hibernate options.
Loop handlers are now implemented in cowboy_long_polling,
and will be renamed throughout the project in a future commit.
Changes include:
* Much simplified route configuration.
* Etag generation is now enabled by default.
* Web mimetypes are now detected by default. A bigger list of
mimetypes can be detected without any additional library.
* Mimetypes can no longer be specified as a list. Copying this
list for new connections is too costy. You can easily convert
it into a function and pass that function to the handler instead.
* You can however specify a single hardcoded mimetype. Mostly
useful when serving a single file, like an index.html file,
to avoid extra operations.
* Specifying a path as a list of tokens is not possible anymore.
Use either a binary or a string.
* Using a private directory will not work if the application
was not started properly. Cowboy will not attempt to find
the location of this directory if the VM doesn't know it,
as this caused issues in some setups.
* Overall the code has been much simplified and clarified,
and of course has now been documented.
