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+==========
+Middleware
+==========
+
+.. module:: django.middleware
+ :synopsis: Django's built-in middleware classes.
+
+This document explains all middleware components that come with Django. For
+information on how how to use them and how to write your own middleware, see
+the :doc:`middleware usage guide </topics/http/middleware>`.
+
+Available middleware
+====================
+
+Cache middleware
+----------------
+
+.. module:: django.middleware.cache
+ :synopsis: Middleware for the site-wide cache.
+
+.. class:: UpdateCacheMiddleware
+
+.. class:: FetchFromCacheMiddleware
+
+Enable the site-wide cache. If these are enabled, each Django-powered page will
+be cached for as long as the :setting:`CACHE_MIDDLEWARE_SECONDS` setting
+defines. See the :doc:`cache documentation </topics/cache>`.
+
+"Common" middleware
+-------------------
+
+.. module:: django.middleware.common
+ :synopsis: Middleware adding "common" conveniences for perfectionists.
+
+.. class:: CommonMiddleware
+
+Adds a few conveniences for perfectionists:
+
+ * Forbids access to user agents in the :setting:`DISALLOWED_USER_AGENTS`
+ setting, which should be a list of strings.
+
+ * Performs URL rewriting based on the :setting:`APPEND_SLASH` and
+ :setting:`PREPEND_WWW` settings.
+
+ If :setting:`APPEND_SLASH` is ``True`` and the initial URL doesn't end
+ with a slash, and it is not found in the URLconf, then a new URL is
+ formed by appending a slash at the end. If this new URL is found in the
+ URLconf, then Django redirects the request to this new URL. Otherwise,
+ the initial URL is processed as usual.
+
+ For example, ``foo.com/bar`` will be redirected to ``foo.com/bar/`` if
+ you don't have a valid URL pattern for ``foo.com/bar`` but *do* have a
+ valid pattern for ``foo.com/bar/``.
+
+ .. versionchanged:: 1.0
+ The behavior of :setting:`APPEND_SLASH` has changed slightly in this
+ version. It didn't used to check whether the pattern was matched in
+ the URLconf.
+
+ If :setting:`PREPEND_WWW` is ``True``, URLs that lack a leading "www."
+ will be redirected to the same URL with a leading "www."
+
+ Both of these options are meant to normalize URLs. The philosophy is that
+ each URL should exist in one, and only one, place. Technically a URL
+ ``foo.com/bar`` is distinct from ``foo.com/bar/`` -- a search-engine
+ indexer would treat them as separate URLs -- so it's best practice to
+ normalize URLs.
+
+ * Sends broken link notification emails to :setting:`MANAGERS` if
+ :setting:`SEND_BROKEN_LINK_EMAILS` is set to ``True``.
+
+ * Handles ETags based on the :setting:`USE_ETAGS` setting. If
+ :setting:`USE_ETAGS` is set to ``True``, Django will calculate an ETag
+ for each request by MD5-hashing the page content, and it'll take care of
+ sending ``Not Modified`` responses, if appropriate.
+
+View metadata middleware
+------------------------
+
+.. module:: django.middleware.doc
+ :synopsis: Middleware to help your app self-document.
+
+.. class:: XViewMiddleware
+
+Sends custom ``X-View`` HTTP headers to HEAD requests that come from IP
+addresses defined in the :setting:`INTERNAL_IPS` setting. This is used by
+Django's :doc:`automatic documentation system </ref/contrib/admin/admindocs>`.
+
+GZIP middleware
+---------------
+
+.. module:: django.middleware.gzip
+ :synopsis: Middleware to serve gziped content for performance.
+
+.. class:: GZipMiddleware
+
+Compresses content for browsers that understand gzip compression (all modern
+browsers).
+
+It is suggested to place this first in the middleware list, so that the
+compression of the response content is the last thing that happens. Will not
+compress content bodies less than 200 bytes long, when the response code is
+something other than 200, JavaScript files (for IE compatibility), or
+responses that have the ``Content-Encoding`` header already specified.
+
+Conditional GET middleware
+--------------------------
+
+.. module:: django.middleware.http
+ :synopsis: Middleware handling advanced HTTP features.
+
+.. class:: ConditionalGetMiddleware
+
+Handles conditional GET operations. If the response has a ``ETag`` or
+``Last-Modified`` header, and the request has ``If-None-Match`` or
+``If-Modified-Since``, the response is replaced by an
+:class:`~django.http.HttpNotModified`.
+
+Also sets the ``Date`` and ``Content-Length`` response-headers.
+
+Reverse proxy middleware
+------------------------
+
+.. class:: SetRemoteAddrFromForwardedFor
+
+.. versionchanged:: 1.1
+
+This middleware was removed in Django 1.1. See :ref:`the release notes
+<removed-setremoteaddrfromforwardedfor-middleware>` for details.
+
+Locale middleware
+-----------------
+
+.. module:: django.middleware.locale
+ :synopsis: Middleware to enable language selection based on the request.
+
+.. class:: LocaleMiddleware
+
+Enables language selection based on data from the request. It customizes
+content for each user. See the :doc:`internationalization documentation
+</topics/i18n/index>`.
+
+Message middleware
+------------------
+
+.. module:: django.contrib.messages.middleware
+ :synopsis: Message middleware.
+
+.. class:: MessageMiddleware
+
+.. versionadded:: 1.2
+ ``MessageMiddleware`` was added.
+
+Enables cookie- and session-based message support. See the
+:doc:`messages documentation </ref/contrib/messages>`.
+
+Session middleware
+------------------
+
+.. module:: django.contrib.sessions.middleware
+ :synopsis: Session middleware.
+
+.. class:: SessionMiddleware
+
+Enables session support. See the :doc:`session documentation
+</topics/http/sessions>`.
+
+Authentication middleware
+-------------------------
+
+.. module:: django.contrib.auth.middleware
+ :synopsis: Authentication middleware.
+
+.. class:: AuthenticationMiddleware
+
+Adds the ``user`` attribute, representing the currently-logged-in user, to
+every incoming ``HttpRequest`` object. See :doc:`Authentication in Web requests
+</topics/auth>`.
+
+CSRF protection middleware
+--------------------------
+
+.. module:: django.middleware.csrf
+ :synopsis: Middleware adding protection against Cross Site Request
+ Forgeries.
+
+.. class:: CsrfMiddleware
+
+.. versionadded:: 1.0
+
+Adds protection against Cross Site Request Forgeries by adding hidden form
+fields to POST forms and checking requests for the correct value. See the
+:doc:`Cross Site Request Forgery protection documentation </ref/contrib/csrf>`.
+
+Transaction middleware
+----------------------
+
+.. module:: django.middleware.transaction
+ :synopsis: Middleware binding a database transaction to each Web request.
+
+.. class:: TransactionMiddleware
+
+Binds commit and rollback to the request/response phase. If a view function
+runs successfully, a commit is done. If it fails with an exception, a rollback
+is done.
+
+The order of this middleware in the stack is important: middleware modules
+running outside of it run with commit-on-save - the default Django behavior.
+Middleware modules running inside it (coming later in the stack) will be under
+the same transaction control as the view functions.
+
+See the :doc:`transaction management documentation </topics/db/transactions>`.