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minor #3653 Http cache validation rewording (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
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Http cache validation rewording

Hiya guys!

This comes after #3596.

I realized that the sentence on the notes was a bid hard to read. I also removed a usage of
the word "client" right before this, so I can use the word "cache" instead (meaning, I want
the user to be thinking about the reverse proxy, not a user's browser cache - that's valid,
but not the typical use-case).

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | -

Thanks!

Commits
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a7cdfe9 [#3596] Tweaking language on HTTP cache
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weaverryan committed Mar 19, 2014
2 parents 0fb2c5f + a7cdfe9 commit 7c0c5d1565a186dfa6be4d65c84d1e8eadf4b540
Showing with 11 additions and 13 deletions.
  1. +11 −13 book/http_cache.rst
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@@ -526,11 +526,9 @@ the application whether or not the cached response is still valid. If the
cache *is* still valid, your application should return a 304 status code
and no content. This tells the cache that it's ok to return the cached response.
Under this model, you mainly save bandwidth as the representation is not
sent twice to the same client (a 304 response is sent instead). But if you
design your application carefully, you might be able to get the bare minimum
data needed to send a 304 response and save CPU also (see below for an implementation
example).
Under this model, you only save CPU if you're able to determine that the
cached response is still valid by doing *less* work than generating the whole
page again (see below for an implementation example).
.. tip::
@@ -578,10 +576,10 @@ automatically sets the ``Response`` status code to 304.
.. note::
The ``If-None-Match`` request header equals the ``ETag`` header of the
last response sent to the client for the particular resource. This is
how the client and server communicate with each other and decide whether
or not the resource has been updated since it was cached.
The cache sets the ``If-None-Match`` header on the request to the ``ETag``
of the original cached response before sending the request back to the
app. This is how the cache and server communicate with each other and
decide whether or not the resource has been updated since it was cached.
This algorithm is simple enough and very generic, but you need to create the
whole ``Response`` before being able to compute the ETag, which is sub-optimal.
@@ -646,10 +644,10 @@ the ``Response`` will be set to a 304 status code.
.. note::
The ``If-Modified-Since`` request header equals the ``Last-Modified``
header of the last response sent to the client for the particular resource.
This is how the client and server communicate with each other and decide
whether or not the resource has been updated since it was cached.
The cache sets the ``If-Modified-Since`` header on the request to the ``Last-Modified``
of the original cached response before sending the request back to the
app. This is how the cache and server communicate with each other and
decide whether or not the resource has been updated since it was cached.
.. index::
single: Cache; Conditional get

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