[Web4lib] ISAPI_Rewrite vs. EZproxy?

[Chris Gray]

On Tue, 18 Oct 2005, Jeremy Dunck wrote:
>
> My understanding was that ISAPI_rewrite was basically Apache's
> mod_rewrite for IIS.
>
> Which is to say, I don't think it does proxying at all.

As the ISAPI_rewrite FAQ, <http://www.isapirewrite.com/faq/>, says, the
module's mission is "to rewrite _requested_ URLs".  In other words, it is
an analog to Apache mod_rewrite
<http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html>, not to the Perl
Apache-RewritingProxy module
<http://search.cpan.org/~hagank/Apache-RewritingProxy-0.7/RewritingProxy.pm>.

So a browser sends a request to your server and ISAPI_rewrite figures out
where the desired page is really, goes and gets it, and passes it back to
the browser.  All this happens in the HTTP request and response headers
not in the actual HTML page that the browser gets.

The question is, how did the browser know, although it wanted a page from
EBSCO, for instance, to ask your server instead of going to the other site
directly.  In the case of EZProxy, it knows because EZProxy rewrites the
proxied page and changes all URLs for EBSCO into URLs for your server.
In the case of ISAPI_rewrite, the browser would have to be told in its
proxy config settings to send all requests for EBSCO to your server
instead.

In other words, on top of ISAPI_rewrite, you're going to need to write a
pac file, <http://www.freeproxy.ru/en/free_proxy/faq/what_is_pac.htm>, and
teach your users to configure their browsers, for example,
<http://proxy.lib.berkeley.edu/configure.calnet.html>.

Having moved from doing this with Apache to using EZProxy, our experience
here is that EZProxy cut way down on the amount of hand holding we've had
to do with users.  UsefulUtilities points to the helpful page on Remote
User Authentication in Libraries <http://library.smc.edu/rpa.htm>.

Chris Gray
Library Systems
University of Waterloo