Rails - Jul 2005 - Detecting cached files on the client ...

Hey everybody,

Is it possible to detect whether dynamically generated data, such as
an image or a pdf, is already cached in the client? This would be data
that is *not* saved on the server''s filesystem. I suppose this would
be a Javascript issue, and it might be off-topic, and I apologize if
so. I just wanted to see if anyone else was doing this with Rails and
where I could find an answer.

Thanks in advance for any help,
Greg

It is possible.

Look at http://wiki.rubyonrails.com/rails/show/HowtoSendFiles which  
has an example querying the If-Modified-Since HTTP header (sent by  
the browser) and sending a "304 Not Modified" response header.

Read up on this at: http://www.w3.org/Protocols/rfc2616/rfc2616- 
sec10.html, Section 10.3.5

Google for "304 not modified" for more info.

Thomas

Am 26.07.2005 um 21:29 schrieb Greg McClure:
> Hey everybody,
>
> Is it possible to detect whether dynamically generated data, such as
> an image or a pdf, is already cached in the client? This would be data
> that is *not* saved on the server''s filesystem. I suppose this
would
> be a Javascript issue, and it might be off-topic, and I apologize if
> so. I just wanted to see if anyone else was doing this with Rails and
> where I could find an answer.
>
> Thanks in advance for any help,
> Greg
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Thomas Fuchs wrote:
> It is possible.
>
> Look at http://wiki.rubyonrails.com/rails/show/HowtoSendFiles which  
> has an example querying the If-Modified-Since HTTP header (sent by  
> the browser) and sending a "304 Not Modified" response header.
>
> Read up on this at: http://www.w3.org/Protocols/rfc2616/rfc2616- 
> sec10.html, Section 10.3.5
>
> Google for "304 not modified" for more info.
>
Another good link is: 
http://fishbowl.pastiche.org/2002/10/21/http_conditional_get_for_rss_hackers

What I want to know is if you do a caches_page or a caches_action to 
generate this file, does the server (Apache or lighttpd) automatically 
work correctly for the If-Modified-Since headers?
> Thomas
>
> Am 26.07.2005 um 21:29 schrieb Greg McClure:
>
>> Hey everybody,
>>
>> Is it possible to detect whether dynamically generated data, such as
>> an image or a pdf, is already cached in the client? This would be data
>> that is *not* saved on the server''s filesystem. I suppose this
would
>> be a Javascript issue, and it might be off-topic, and I apologize if
>> so. I just wanted to see if anyone else was doing this with Rails and
>> where I could find an answer.
>>
>> Thanks in advance for any help,
>> Greg
>> _______________________________________________
>> Rails mailing list
>> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>>
>
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>