IIS problem with secure chunked transfer

Hi IIS gurus,

My Java applet sends large POST requests to an IIS 5.0 ISAPI extension
using chunked transfer. This works fine for secure servers (defined as
"Require SSL").

Alas, when I define the IIS virtual dir as "Require client
certificate". In this case, the applet sends the chunks but IIS
accumulates them in memory. inetinfo.exe memory keeps growing and
takes 98% CPU. Only when the last chunk arrives, IIS invokes the ISAPI
extension and lets it read the entire POST request (consisting of 50
chunks of 500KB each). Not only IIS takes huge memory, but the
transfer is extremely slow (2-3 minutes!).

Interestingly, I have the same client written in ActiveX. this client
does exactly the same chunked transfer as the Java applet (and to the
same server), but the transfer is very fast and there are no delays on
the IIS side.

Is there any cure? Is this a Java or IIS problem?
Any help would be greatly appreciated.

Sruli Ganor

This sounds like a tough one to troubleshoot. I'd recommend getting a
network monitor trace to see how the packets differ. But obviously since it
is SSL you aren't going to get very useful data that way. Since you see
high CPU during this upload the easiest way I can think of to see what is
going on would be to get a memory dump on IIS during the issue. The problem
is most likely related to how the ISAPI filter is handling some subtle
difference in the packets.

Recommendation:
1. Do some Internet searches for IISSTATE
2. Download, install, and get this tool configured properly.
3. Run IISSTATE during your POST that has a problem.
4. Post the IISSTATE output here.

Thanks,
Brian