Re: Digex transparent proxying

[Karl Denninger <karl () mcs net>]

On Sat, Jun 27, 1998 at 08:07:46AM -0400, Rich Sena wrote:
> On Sat, 27 Jun 1998, Karl Denninger wrote:
>
> > And as soon as people doing advertising actually do this, then the proxy
> > becomes less useful, leading proxy owners to ignore the headers so that their
> > multi-thousand-dollar investments in these things are not wasted and
> > actually HURT performance (performance for the FIRST fetch through a proxy
> > is SLOWER - it HAS TO BE, since the proxy must first get the data before it
> > can pass it on).
>
> If a proxy owner ignores expires heades than as I said he/she/it better
> understand what is going on and what he/she/it is doing - they are
> potentially causing harm to their end users.  

A proxy owner who doesn't ignore them is going to see less and less impact
as time goes on, because less and less web content is both static and not
frequently updated.

> > And how do you guarantee that the proxy server is parsing the tags and not
> > ignoring them?
>
> Hold on hit the brakes there Karl ma boy - I DID NOT SAY - that the proxy
> server will parse the tags - most can and do NOT parse the tags - that
> would slow them down to a crawl while they waste valuable resources
> parsing html - What I said is to make sure that your content provider (who
> is serving your (the site designer's) site parse html on teh SERVER - so
> that the cache/proxy will see it as an appropriate HTTP header - then you
> have no problem

My language was imprecise.  

What I was referring to was the headers indicating whether or not content
can be cached, and also what the expiration time is.

Proxy caches are only useful to the extent that a reasonably-significant
amount of traffic IS referred to more than one, is not LOCALLY cached in the
browser (ie: the model is two or more people accessing the same thing BEFORE
the timeout happens) AND the content has correctly set the proper expiration
policy.

That is becoming less and less true over time.

> > Proxies are fine WHERE CUSTOMERS HAVE AGREED TO THEIR USE.
>
> Yup you have to agree to use a proxie (it requires you to set it in your
> browser) a transparant cache is another story - and IMHO TRANSPARENT
> caches have their place closer to the enduser - they can be a problem if
> placed to far up the ladder.

I have no problem with a proxy where the user has agreed to its use.

I have a major problem with a provider hijacking a stream of data and
reprocessing it, then delivering what the client *thinks* is a direct
communication session.

In fact, I'm not even sure that such an act, absent consent, is legal.

--
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