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From "Roy T. Fielding" <field...@kiwi.ICS.UCI.EDU>
Subject Re: [PATCH] Filter registration.
Date Wed, 26 Jul 2000 01:16:51 GMT
>Roy seems to argue that ->r shouldn't be present anywhere in there. I think
>that position is too idealistic, so I'm not listening to it :-)  No,
>seriously, if we *can* get to a point where the request_rec isn't needed in
>a filter, then it will be easier to remove the sucker from the structure
>than from the signatures. [because (theoretically) nobody is referring to
>->r any more]

To be more specific, the only filter that can be allowed to modify the
request record is the HTTP protocol filter -- all other filters can only
use it to view request info (like the request header fields, etc.), and
even then only if r is passed as part of the filter instantiation.

Why?  Because from the perspective of each filter, the request_rec is
a global variable.  Setting variables (like headers_out) within the
global variable causes the nature of the output data stream to change
without that change being passed to downstream filters. It is therefore
forbidden and the only way to change the request_rec is by passing metadata
downstream to the one filter that owns the request_rec -- the HTTP filter.

....Roy

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