Re: Auto Resume proxy downloads

On Wed, 21 Jan 1998, Steve Judge wrote:

> Does squid support auto resumes on downloads ??

In general, if client<->proxy connection is terminated when "significant"
portion of the document has been already fetch from network, Squid does
not terminate outgoing connection and gets the entire document. There are
a few parameters in newer config. files that define "significant".

Now, if a client wants to get the document again, it either asks for the
whole thing (slow, but still much better than if Squid did not cache it)
OR, if client is smart enough, it can ask for a specific _range_ of the
document (e.g. last 50KB out of 2MB doc). In the second case, Squid 1.1
returns the entire document, and Squid 1.2 will return the range requested
by client.

[ Squid 1.2 will not _cache_ partial content though. Usually, range
headers will be stripped out before making a request to the primary
server. ]

> There is a product out on the market now called Go!Zilla that when you
> choose a file for downloading through your browser it goes out and finds
> the fastest download site for you to get it from over the net.

I do not think it is feasible unless Go!Zilla does it for _well-known_ or
popular documents only. Think, how can you get the fastest site for
"www.never-seen.com/never-heard.html" if you do not have a database of its
possible locations and do not know how the ".mirrors" file is called on
that particular server? This is one of the problems addressed by URNs.

> It also supports resuming of aborted downloads if the server or proxy server
> supports it.

See above.

> It lets you put your proxy server in the settings which works great!
> But, when downloading with proxies turned on in Go!Zilla it comes up with
> download cannot be resumed, but as soon as proxies are turned off it
> reports that downloads can be resumed.

Looks like it is using Range requests. Wait for Squid 1.2.

Alex.

P.S.

> This was downloading from ftp sites.

Does FTP support an equivalent of HTTP Range requests? Anybody? If it
does, it will be supported in Squid 1.2, I guess.
Received on Tue Jan 20 1998 - 23:28:07 MST