uncacheable

The only value valid in an Expires header is a HTTP date; anything else will most likely be interpreted as 'in the past', so that the representation is uncacheable.

Lightly Toasted 2010

By default, representations processed by PHP are not assigned validators, and are therefore uncacheable.

Lightly Toasted 2010

If no validator (an ETag or Last-Modified header) is present on a response, and it doesn't have any explicit freshness information, it will usually - but not always - be considered uncacheable.

Lightly Toasted 2010

So what does it mean if I have HTTP caching of strongly and weakly uncacheable data?

Popular Posts Across MetaFilter 2010

HTTP header to a representation will make it uncacheable.

Lightly Toasted 2010

These meta tags are often used in the belief that they can mark a document as uncacheable, or expire it at a certain time.

Lightly Toasted 2010

If you must know every time a page is accessed, select ONE small item on a page (or the page itself), and make it uncacheable, by giving it a suitable headers.

Lightly Toasted 2010

For example, you could refer to a 1x1 transparent uncacheable image from each page.

Lightly Toasted 2010

Next we see a bunch of "exceptions" -- regions of memory each marked as uncacheable.

Slashdot: Linux 2009

Since at least one of these headers is needed by HTTP clients to implement caching, this means that these files become uncacheable and everything from wget to apt will fully download them every time.

Planet Debian Marco d'Itri 2009