recoverable downloads - opinions sought

Robert Collins
Mon Nov 26 21:47:00 GMT 2001

----- Original Message -----
From: "Christopher Faylor" <>
To: <>
Sent: Tuesday, November 27, 2001 3:58 PM
Subject: Re: recoverable downloads - opinions sought

> On Sat, Nov 24, 2001 at 07:23:15AM +1100, Robert Collins wrote:
> >To do recoverable downloads we need 2 things.
> >1) A way to check the file, other than filesize, for integrity. MD5
> >do and IIRC that's already caclulated on sources.redhat.
> >2) Code to pickup partway through and carry on.
> >
> >For 2) we can either code it internally, or link statically to
> >like libcurl, or call out to wget/curl.
> I don't understand why we need an external library for this.  Isn't
> just a simple "start here when downloading" type of operation?  I know
> the ftp protocol allows this.  I'm not sure about http.

FTP/HTTP/fileio/any other protocols we support in the future should all
support this to some extent or another. It's more a duplication of
effort thing really, I don't really like writing YAFC and YAHC when good
clients are in libraries already, and with C++ bindings we can save time
and effort.

As for the code complexity, FTP *optionally* supports the REST command,
but some FTP servers don't, so it cannot be assumed. As for HTTP, the
server as the option to return the entire file anyway, and there are
(IIRC) 3 different ways the response can be addressed. Se above on
duplication of effort.


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