[Zope] Image Caching

[Peter Sabaini]

http://www.mnot.net/cache_docs/

is a good resource on caching, http headers necessary etc. 

cheers, peter.

On Wed, 12 Jun 2002, Dieter Maurer wrote:

> Smith, Neil writes:
>  > I seem to remember having read something in the list before about problems
>  > with caching of images, but I can't find it again.
>  > 
>  > Is there anything that would cause an image used multiple times on the page
>  > not to be read from the cache?
>  > 
>  > I have a form that uses JavaScript to display itself, such that it can do a
>  > sort of tabbed interface and add new lines to the form without going back to
>  > the server.  This contains a  number of very small images that are
>  > frequently repeated to build up the borders of the tabs etc.
>  > 
>  > This works well when used on the LAN, but I've now found that when used
>  > across the internet, when the form redisplays itself, it takes forever to
>  > build up the graphics, and you can see each individual image being slowly
>  > loaded.  I'd thought it would have got the images from the cache.
> There are many, many parameters that control caching.
> See the HTTP/1.1 spec for details.
> 
> Maybe, you have caching disabled in your browser?
> 
> The spec tells that many responses must not be cached:
> 
>   *  responses to requests with a query string
>   *  responses to post requests
>   *  responses to requests that require authorization (usually not implemented)
>   *  responses with corresponding cache control headers
>   *  responses lacking a "Modified" and "Etag" header
>   *  ....
> 
> difficult to tell what case prevents caching for you.
> 
> 
> Dieter
> 
> 
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