06e74355c0
Has some stuff that aren't in master yet, and lacks a lot more that is already in master.
1.1 KiB
Handlers
Purpose
Handlers are Erlang modules that represent a resource.
Handlers must process the request and send a reply. The nature of the reply will vary between handlers.
Different kinds of handlers can be combined in a single module. This allows a module to handle both websocket and long-polling code in a single place, for example.
Protocol upgrades
Cowboy features many different handlers: HTTP handlers, loop handlers,
websocket handlers, REST handlers and static handlers. All of them
have a common entry point: the init/3 function.
By default, Cowboy considers your handler to be an HTTP handler.
To switch to a different protocol, like, for example, Websocket,
you must perform a protocol upgrade. This is done by returning
a protocol upgrade tuple at the end of init/3.
The following snippet upgrades the handler to my_protocol.
init(_Any, _Req, _Opts) ->
{upgrade, protocol, my_protocol}.
The my_protocol module will be used for further processing of the
request. It requires only one callback, upgrade/4.
@todo Describe upgrade/4 when the middleware code gets pushed.