[WEB4LIB] Re: Microsoft Proxy Server 2.0

[Jon Knight]

On Tue, 13 Apr 1999, Catherine Delia wrote:
> What is the best alternative to a proxy server for off campus/remote
> access to databases? We have people clamoring for it right now. All our
> databases are IP authenticated to the campus network addresses. 

Well the alternative is going direct, either straight from the browser
using a set of proxy exceptions or by having you local cache forward on
requests without bothering to cache them or check its cache.  In which
case one of the main reasons for a proxy is lost (you might have others
such as negotiating a firewall or bandwidth throttling outgoing traffic
from your site of course).

The main problem for us (and many other .ac.uk sites that subscribe to web
based databases that use IP authentication) is the the campus proxy is a
Squid cache that is part of the UK academic national cache hierarchy. This
means that if it gets a request for a page that it doesn't have, it asks
its "sibling" caches at other local Universities and also its "parent"
caches at the UK National cache (which coincidentally is partly based here
at Loughborough) if they have it before requesting it itself.  This gives
excellent performance and really cuts down on transatlantic charges but
also means that if the remote service is using IP authentication they'll
get the wrong IP address some of the time. 

The upshot of which is either that our users are denied access (because a
"parent" or "sibling" with no rights to the remote service has tried to
access it and cached a "no entry" page) or we get it and then also hand
it out to other caches at a later date (so that people with no
subscription get to use some of the service).  HTTP provides cache control
mechanisms that Squid obeys but few information providers seem to use or
understand them.

The other problem with caching proxies is that some of the more "glitz
before content or usefulness" sites rely on finding what browser is
accessing them and with what options.  Caching proxy can sometime screw
this up..  Of course no library subscription resources are content free
glitz but lots of popular sites with users are.

Tatty bye,

Jim'll