> Sections 13 - 14.9 of the RFC 2616 HTTP 1.1 specification
> 
> http://www.w3.org/Protocols/rfc2616/rfc2616.html
> 
> <snip>
> The Cache-Control general-header field is used to specify 
> directives that MUST be obeyed by all caching mechanisms 
> along the request/response chain </snip>

        sure, but with desktop boxes in the basement of every joe
sixpack, that's not going to help a lot, as these people connect without
a caching mechanism between themselves and the site. So if they pull
your sites content, the content is re-rendered. A second request will
likely hit the browsercache, but it first has to get there. A caching
mechanism on teh server avoids that re-render, it simply sends the
cached output.

                Frans.

> 
> 
> -----Original Message-----
> From: Unmoderated discussion of advanced .NET topics.
> [mailto:[EMAIL PROTECTED] On Behalf Of Frans Bouma
> Sent: 12 October 2004 12:19
> To: [EMAIL PROTECTED]
> Subject: Re: [ADVANCED-DOTNET] MiddleTier Caching was Abstracting SQL
> 
> Isn't that caching header used to control proxy server caches? I.e.:
> when 500,000 desktop boxes connect to your website, not 
> through a proxy, your pages will be rendered 500,000 times. I 
> think the poster was asking for a caching solution on the 
> webserver itself, so no matter what is used on the client 
> side (or the route to the client side) the server is not 
> under stess when the site receives a lot of requests
> 
>         Frans.
> 
> > IIS5/6 are both capable of adding a cache-control header; 
> part of the 
> > HTTP
> > 1.1 protocol - ASP.NET simply adds this header when using the 
> > OutputCache directive, to the outgoing HTTP stream - you may notice 
> > that static items, such as images etc are always cached by 
> default by 
> > the IE cache on the client.
> >
> > Using the cache-control headers it's possible to force 
> content to be 
> > cached in several locations, ranging from client, server and any 
> > intermediate point of presence server (ISP cache/proxy) in the 
> > internet.
> >
> > ASP was designed to serve dynamic content not static 
> content, such as 
> > HTML/images. It's normal practice to try and offload the serving of 
> > static content onto publishing servers i.e.
> > caching servers e.g. ISA server - therefore allowing IIS/ASP to do 
> > what it's meant to i.e. serve dynamic content.
> >
> > Each virtual dir in IIS5/6 can be set to add cache-control headers 
> > (this does not require ASP.NET and can be used for any web 
> application 
> > including VB6, PHP etc)
> >
> > You can set the cache-control header by looking at the HTTP headers 
> > tab of your vdir - it's possible to set an absolute time out, or 
> > minutes, hours, days etc
> >
> > I hope this helps, but beware caching too much content can actually 
> > degrade system performance - the machine will use a larger 
> amount of 
> > resources and may take longer to look up the cached page it may be 
> > quicker to simply regenerating it from the originating server - you 
> > should test this before employing a caching strategy.
> >
> > Regards,
> > Andrew
> >
> > Developmentor Instructor
> > Course Author
> >
> >
> > -----Original Message-----
> > From: Unmoderated discussion of advanced .NET topics.
> > [mailto:[EMAIL PROTECTED] On Behalf Of 
> Frans Bouma
> > Sent: 12 October 2004 10:28
> > To: [EMAIL PROTECTED]
> > Subject: Re: [ADVANCED-DOTNET] MiddleTier Caching was 
> Abstracting SQL
> >
> > > Frans Bouma wrote:
> > > > To save webserver power because the website gets 500,000
> > > hits per day?
> > > > Perhaps a page caching with 1 minute per page will help.
> > Often that
> > > > will give much more performance boosts than lowlevel
> > caching with a
> > > > lot of overhead.
> > > >
> > > This is what we often do, but when the cache invalidates,
> > those 500000
> > > hits are wanting to update the cache and flood the db, I am 
> > > exaggerating but you catch my drift :D Any one ideas how 
> to prevent 
> > > the flooding of the db (in a VB6 world) ?
> >
> >         If a page cache invalidates, the first request will hit the 
> > db, the second will get the cached version.
> >
> >         But you can also use the system used by for example 
> slashdot.
> > Say your webserver farm can render ALL the pages you want 
> caching for 
> > in 10 seconds. This means that if you re-render all these 
> pages every 
> > 20 seconds, your system will perform nicely no matter how many hits 
> > your system gets, although performance can degrade a little 
> when more 
> > requests come in.
> > After the site is rendered, it is cached completely till the next 
> > re-render (which is using a render to cache mechanism)
> >
> >         The beauty of the system is that when extra performance is 
> > required, you simply crank up the interval:
> > not every 20 seconds, but every minute you do a re-render.
> >
> >                 Frans.
> >
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