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From "Bill Stoddard" <stodd...@raleigh.ibm.com>
Subject Re: AP_FTYPE_CONNECTION == BUFF + IOLs
Date Thu, 24 Aug 2000 14:11:55 GMT

> On Wed, 23 Aug 2000, Bill Stoddard wrote:
>
> > I have not been following the evolution of filters closely, so
perhaps this question
> > displays my ignorance...   It seems to me that we are trying to cram
too much function
> > into filters. Doesn't it make more sense to use BUFF and IOLs to do
AP_FTYPE_CONNECTION
> > type filtering?
>
> Grrrr....  No this doesn't make sense.  IOLs are just watered down
> buckets.

IOLs have an interface symantically similar to sockets with the ability
to read from or write to any data sink/store. The support setting the
read/write interface blocking or non-blocking.  Very simple
conceptually. Now, we have to create a 'bucket' with a funky looking
interface for each data source and data sink. You pass in a variable to
tell the i/o hidden in the bucket whether it needs to block or not.
It's crufty at best.  Buckets and filters makese sense to me for
filtering content, but they make no sense as a replacement for IOLs. How
are you going to implement something like ap_send_fb() using buckets and
filters that is easy to see and understand?  We are trying to use
filters to fix all of Apache's problems.

> They were Deans first attempt, and while they are close, they
> aren't quite right.  Buffs are just ugly, and part of the point of
this
> was to remove Buff from the code, because nobody really understands
the
> guts of it.

You don't understand how BUFF works, so you are replacing it. Do I
really need to point out the logic error here?

The function in BUFF is there for a reason. If we do not fully
understand what function we need to replicate (and we apparently don't)
then we will rediscover it piece by painful piece, hack solutions into
the filter code and end up with a beast more ugly than what we started
with. Stream of conscienceness design is fine just so long as you know
when you are doing it and are prepared for the consequences. Be prepared
to scrap everything and start over when you figure out you've designed
youself into a corner.

Bill



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