Re: Re: limiting access

> Yes, fair enough. Using conditionals in HEAD requests is
> unnecessarily conservative if you expect and want to download the
> latest. It would be less efficient to make two requests.

Less efficient how?  In that the request process would be two hits if the
content was known to be completely changing?  Yes, perhaps it might.  But
for the great many feeds we watch via Syndic8 the number that don't change
as frequently as many aggregators default to using is considerable.  It
would be of GREAT savings on both ends to use both HEAD requests and conneg
headers.  Make the request based on what you know and let the server
likewise make educated decisions about what to deliver.  If the server's
known to accept and correctly used header negotiation then a HEAD request
wouldn't be needed.  Trouble is it's difficult know which ones do and which
ones don't.  Erring on the side of conservation seems like a reasonably good
idea.

> The potential saving on the content body is not significant unless you're
> checking thousands of feeds which are not updated as often as they
> claim to be!

Or if you're the feed source and you're getting beat up by countless
individual aggregators all with too-short a retry interval.

This isn't to argue that anyone's wrong here.  More thar arguments about
savings or waste based on lightening the load of the programmer making the
aggregator are perhaps falsely economic.  It's far better to make the
developer of an aggregator put forth the rather trivial amount of effort to
track the data and make informed requests of the source than to turn loose
more crappy software that crucifies the feed servers needlessly.

Yes, it will take the developer a little more time to write the code to
store the last change data and use it when making subsequent requests for
the feed.  It might likewise make a little more work for the feed provider
if they're generating the feed from a dynamic script.  It can help make the
transfer more efficient to serve up only the items detected from the
requested date.  For someone using most blog software that renders to static
files they need do nothing to their server.  The savings, however, when
things start scaling up can be significant.  Especially for the small site
faced with sudden uptake of it's feed.  But even for the heavily used sites
it's worth considering.

-Bill Kearney
Syndic8.com



 
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