Controller Callbacks

[OpenStack Infra]

https://review.openstack.org/34948
commit 76ca383da1f52687cd439c31ff1cc561a6e75dcc
Author: David Hadas <email address hidden>
Date: Fri Jun 28 22:20:33 2013 +0300

    Controller Callbacks

    A callback mechanism was added to allow middleware to register
    callbacks from a/c/o controllers allowing easier core swift
    extendiability by middleware.

    The callback takes the form:
          resp = controller_callback(req, resp)

    Any middleware using the callback mechanism should chain
    its callback to previous callbacks - i.e. it is tasked to
    call any other callback it replaces when adding itself.

    DocImpact

    Bug: #1195861
    Change-Id: I7ef756cb7030e1189a0ba74da5b3cf689969b2c6

[Tom Fifield (fifieldt)]

Nice doc in the patch. good for ops guide customising chapter

[Tom Fifield (fifieldt)]

I think this is fine where it is in the swift devref, and doesn't need to go in the ops guide