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1995-06-24
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Help on Proxies and how to use them
===================================
In message <19950605.222342.63@sitex.demon.co.uk> Neil Tarrant wrote:
A proxy machine is an HTTP server that 'passes on' requests to other sites.
It requests the document on your behalf.
At first this may seem a little pointless, but after using one for a while
you'll really appreciate the benefits. Most internet WWW users browse
pages in the United States. Going over to the States each time you want to
read a HTTP doc is sluggish (to say the least). A proxy HOLDS recent copies
of *popular* documents and hence can often give a **MUCH** faster response. A
good example of this is 'http://www.playboy.com/' which is a *very* popular
home page. Accessing this without the proxy is very slow, but with the proxy,
response is *very* fast.
HTTP proxy is also very useful when browsing European sites. Not many
people realise that requests to Europe USUALLY go via the US, which adds
a hell of an overhead to the request time (it's often faster accessing
Australia).
The other important use of proxy machines (well some anyway) is that they
provide non-HTTP resource conversion. For example, gopher requests return
gibberish if fetched directly, but a proxy will translate the gibberish
into a nicely laid out HTTP document. The same is true of FTP (etc), which
is tricky to provide via a local client fetcher.
Therefore an application such as WebGopher, can provide HTTP, gopher, ftp
and others, without much programming. [ArcWebTCP will handle HTTP and FTP
requests itself, and use the resource conversion utilities for gopher and
WAIS. Ed.]
Note, however, WebGopher can do (and only does) direct gopher fetching,
'coz it's nicer', but the others can be done via a different proxy. FTP,
for example, is ONLY handled via the proxy (it took me all of 15 minutes
to add FTP support this way).
Direct fetching is usually more efficient for non-HTTP protocols, as it's
mainly for HTTP (that's where most benefits will be gained).
[If you want to use proxies, and you are a Demon customer, then use,
www.demon.co.uk on port 80 as your HTTP proxy and also for FTP, gopher and
WAIS. If you in the UK academic community then use wwwcache.hensa.ac.uk on
port 8080 except WAIS which is on port 80 on wwwcache.hensa.ac.uk Ed.].
NOTE: It is considered 'rude' to use an external proxy UNLESS you have
no viable alternative (ie use demon instead of hensa for HTTP), as it
places undesirable strain on the overloaded general proxy machines.
I hope this clears up the confusion many new users seem to have regarding
proxy machine usage. :-)
[For more details on how ArcWebTCP handles proxies, load ArcWeb and click
on the icon bar icon to open the welcome page. Then follow the link to
the User Manual and then follow the 'Proxy' link. Ed.]
--------------------
Neil Tarrant
(Modifications by S.Brodie marked as [Ed.])