[TYPO3-core] RFC #17167: Cache ExtDirect::getAPI calls

[Steffen Gebert]

>header_remove('Last-Modified');
 >
> And it seems to have helped, no more calls to ExtDirect::getAPI when
> clicking around. Only when one do a explicit "reload" of the whole
> backend, all those resources are fetched again (which caused me some
> time to figure out that it works differently between clicking around and
> hitting reload...).
>
> So I would say, we commit this follow-up (PHP 5.2 compatible). Could you
> last-check it and do it, please, Steffen? Thanks!

Hi,

I've been discussing with Stefan for a while now. He pointed me to 
Google Page Speed > Optimize Caching page [1]

 > It is important to specify one of Expires or Cache-Control max-age,
 > and one of Last-Modified or ETag, for all cacheable resources. It is
 > redundant to specify both Expires and Cache-Control: max-age, or to
 > specify both Last-Modified and ETag.
So, we should better not remove that header.

Situation is a bit weird:
 > Expires and Cache-Control: max-age. These specify the “freshness
 > lifetime” of a resource, that is, the time period during which the
 > browser can use the cached resource without checking to see if a new
 > version is available from the web server. They are "strong caching
 > headers" that apply unconditionally; that is, once they're set and
 > the resource is downloaded, the browser will not issue any GET
 > requests for the resource until the expiry date or maximum age is
 > reached.
That's the situation, we currently have. However, the browser *does* 
these requests.

Furthermore, they state
 > If the Last-Modified date is sufficiently far enough in the past,
 > chances are the browser won't refetch it.
So.. what is old enough? I tried setting the Last-Modified header to -1 
year. However, Chrome still asked the server and got a 304 response (I 
was working with static files, but for the ExtDirect thing, this would 
be a normal 200 response containing the full content).

So.. the solution we had looked pretty good.. however.. google says that 
we're doing bad things.

W.r.t the situation of being pretty close to RC1 and final: Keep it as 
is and find out during development of 4.6, whether this is good or not.

Kind regards
Steffen

-- 
[1] http://code.google.com/intl/de-DE/speed/page-speed/docs/caching.html

Steffen Gebert
TYPO3 Core Team Member

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