Re: RSS Revision - IssueMinimumOneItem

> but just in case you want a practical use case this is in similar
> territory to Apache Gump's feed. Can't remember the details, but the
> challenge was getting it to flag a change in state (ok-notOk) as news
> rather than a continuous ok-ok-ok-ok-notOk-notOk-notOk...

Yes, this is sort of hard to do "efficiently" with RSS as it's typically
seen in the wild.

Most feeds are static files.  They're often expected to be downloaded
"whole" and used as such.  This has not been without it's hassles due to
missing uniqueness identifiers and assorted other issues.  While using a
static document introduces some problems it solved the question of how to
offer up database driven data without putting undue burden on the server.

Given that at the time RSS feeds came onto the scene it was quite common NOT
to be able to run server-side code.  No perl or cgi scripts, no php or asp
server-side pages.  Thus it wasn't practical to provide any way to 'adjust'
or otherwise change the data being requested.  This has changed to some
extent as many hosting environments now offer a wealth of server-side
processing options.

It still remains a balancing act between the 'waste' of bandwidth using
static files downloaded over and over versus the CPU load of repeated script
execution pulling fresh info from a database (along with the DB overhead).
TANSTAAFL, as the saying goes.

Unless a feed source is driven dynamically there's not much that can be
done.  And even when using dynamically driven scripts it's difficult to work
around the limitations of many consuming client programs.  There's always
the 'out' of using controlled subscriptions using HTTP authentication
(remembering the user and their last state) but this isn't foolproof and
many client programs won't do it anyway.

-Bill Kearney



 
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