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From Andy Armstrong <>
Subject Re: Anyone know why the ISAPI redirector works how it does?
Date Sun, 24 Jun 2001 00:13:15 GMT
"Ignacio J. Ortega" wrote:
> AFAIK only the request that need to be served by the Extension , that is
> request that match the config present in UWM.P file are routed to the
> extension , that runs in other priority thread, if you serve the Tomcat
> request directly from the filter therad you are blocking the filter
> thread in Tomcat.., and i repeat *ALL* the request served by an IIS
> server are passed to ALL the filters..not only the Tomcat  one.. so if
> the ISAPI extension were working like you are proposing you are blocking
> the main server thread waiting for tomcat to serve the request, many
> unrelated request will be slowed appreciably and the overall capacity of
> the server will be greatly impacted...

Thanks Ignacio; I understand what you're saying now. If all the filters
run in the same thread that implies that IIS handles all its requests in
a single thread, which seems unlikely, but of course I could be wrong.

> I think there are good reasons to keep things as they are now...i dont
> found a good reason , apart from code complexity , to do what you are
> proposing ..but i'm not a ISAPI expert...I could be wrong.. i'm only
> repeating to you the reasons Gal said to my many time ago.. you can
> consult archives about May past year .. (i'm doing so now i wil try to
> document it )

I'd be interested in anything you can find. I don't expect it to involve
too much work, so I'm going to build it and do some performance testing
to find out if there are any problems. From what you're saying the
performance problem to look for would be lots of Tomcat requests having
an adverse affect on the performance for non-Tomcat IIS requests.

> But i'm open to test and help in what you are proposing .. i'm not
> trying to block you from doing so .. i'm only trying to left the old
> code as it is, you can do what you are proposing in another directory in
> jtc and call it with a funny name ( IISTHAR ? :), and we can test and
> use it as an alternative .. if everything works as you expect .. good ..
> if not we still have that good old code ... users need a escape way from
> developers. :)

I'm putting it in a directory called 'isapi' and leaving 'iis' intact.
In any case I have some more work to do on the existing IIS redirector
to make it work properly with the latest jk code, but that's a separate
issue, and I won't do anything too scary to the current IIS code.

Andy Armstrong, Tagish

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