[Web-SIG] A more Twisted approach to async apps in WSGI
ianb at colorstudy.com
Tue Oct 5 20:19:37 CEST 2004
James Y Knight wrote:
> However, interaction with middleware seems quite tricky here:
> - For input modifying middleware: I guess on_get would have to just
> raise an exception if wsgi.input has been replaced. If the input stream
> was iterable, an on_get callback could just be considered notice that
> you can iterate the input stream once without blocking, assuming the
> block boundary requirements were also in effect here. Then it would work
> right even if the input stream was replaced. However, I think it might
> be the case that middleware that wants to modify the input stream is so
> rare, it doesn't really matter.
I think middleware would have to modify the input stream if it wanted to
parse POST variables. In that case, you might parse the input stream,
while also constructing a replacement input stream for when the
application tries to re-read the stream. In effect the middleware wants
to peek at the input stream.
I can't think of any other useful reasons to modify the input stream,
but this one seems fairly reasonable. For instance, a piece of
middleware might try to detect a login attempt by looking for particular
field names in the request.
Ian Bicking / ianb at colorstudy.com / http://blog.ianbicking.org
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