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|
= cowboy_middleware(3)
== Name
cowboy_middleware - Middlewares
== Description
The module `cowboy_middleware` defines a callback interface for
Cowboy middlewares.
Middlewares process the request sequentially in the order they
are configured.
== Callbacks
Middlewares implement the following interface:
[source,erlang]
----
execute(Req, Env)
-> {ok, Req, Env}
| {suspend, module(), atom(), [any()]}
| {stop, Req}
Req :: cowboy_req:req()
Env :: cowboy_middleware:env()
----
The `execute/2` is the only callback that needs to be
implemented. It must execute the middleware and return
with instructions for Cowboy.
ok::
Cowboy should continue processing the request using the
returned Req object and environment.
suspend::
Cowboy will hibernate the process. When resuming, Cowboy
will apply the returned module, function and arguments.
stop::
Cowboy will stop middleware execution. No other middleware
will be executed. This effectively ends the processing of
the request.
// @todo No need to return the Req when stopping. Fix in 3.0.
== Types
=== env()
[source,erlang]
----
env() :: #{atom() => any()}
----
Middleware environment.
A new environment is created for every request. The initial
environment contained the user configured environment values
(like `dispatch` for example) plus the `listener` value which
contains the name of the listener for this connection.
Middlewares may modify the environment as necessary.
== Changelog
* *2.0*: The `env` type is now a map instead of a proplist.
* *1.0*: Behavior introduced.
== See also
link:man:cowboy(7)[cowboy(7)]
|
