PSGI::Extensions - PSGI extensions
The PSGI environment MAY include the following additional extensions. They are
OPTIONAL and applications and middleware components SHOULD check if they exist
in the environment before using the functionality provided.
- "psgix.io": The raw IO socket to access
the client connection to do low-level socket operations. This is only
available in PSGI servers that run as an HTTP server, and should be used
when (and only when) you want to jailbreak out of PSGI abstraction,
to implement protocols over HTTP such as BOSH or WebSocket.
- "psgix.input.buffered": A boolean which
is true if the HTTP request body (for POST or PUT requests) is buffered
using a temporary filehandle or PerlIO in
"psgi.input". When this is set,
applications or middleware components can safely
"read" from
"psgi.input" without worrying about
non-blocking I/O and then can call
"seek" to rewind the input for the
transparent access.
- "psgix.logger": A code reference to log
messages. The code reference is passed one argument as a hash reference
that represents a message to be logged. The hash reference MUST include at
least two keys: "level" and
"message" where
"level" MUST be one of the following
strings: "debug",
"info",
"warn",
"error" and
"fatal".
"message" SHOULD be a plain string or a
scalar variable that stringifies.
- "psgix.session": A hash reference for
storing and retrieving session data. Updates made on this hash reference
SHOULD be persisted by middleware components and SHOULD be restored in the
succeeding requests. How to persist and restore session data, as well as
how to identify the requesting clients are implementation specific.
"psgix.session.options": A
hash reference to tell Middleware components how to manipulate session
data after the request. Acceptable keys and values are implementation
specific.
- "psgix.harakiri": A boolean which is
true if the PSGI server supports harakiri mode, that kills a worker
(typically a forked child process) after the current request is complete.
"psgix.harakiri.commit": A
boolean which is set to true by the PSGI application or middleware when
it wants the server to kill the worker after the current request.
- "psgix.cleanup" - A boolean flag
indicating whether a PSGI server supports cleanup handlers. Absence of the
key assumes false (i.e. unsupported). Middleware and applications MUST
check this key before utilizing the cleanup handlers.
"psgix.cleanup.handlers" -
Array reference to stack callback handlers. This reference MUST be
initialized as an empty array reference by the servers. Applications can
register the callbacks by simply push()ing a code reference to
this array reference. Callbacks will be called once a request is
complete, and will receive $env as its first
argument, and return value of the callbacks will be simply ignored. An
exception thrown inside callbacks MAY also be ignored.
If the server also supports
"psgix.harakiri", it SHOULD implement
in a way that cleanup handlers run before harakiri checker, so that the
cleanup handlers can commit the harakiri flag.
Copyright Tatsuhiko Miyagawa, 2009-2011.
This document is licensed under the Creative Commons license
by-sa.