Apache proxy to IIS

[Rod Widdowson]

> I new to Shibboleth.  I have an Apache server with the SP installed.  It works fine.  We have one application that 
> runs on IIS.  For that
> application, I have Apache reverse proxy to IIS.
> 

If I understand you properly, as far as Shibboleth is concerned IIS is irrelevant.  As far as the SP is concerned the "Application" is on Apache, in this case the "Application" is the reverse proxy to IIS.

So the question you appear to be asking has nothing to do Shibboleth and is "Can the Apache Reverse Proxy provide information to IIS derived from server variables?".  

/R