Kai Schaetzl wrote:

> > Now, why the heck is IIS Gzipping and Chunking a file,
>
> because it is configured to do so. I thought you were aware that it
> sends gzipped and I didn't know it's doing that for zipped files as
> well. So I didn't mention it. You should configure the server to not
> gzip any binary files. There is no use to send zip, gif or jpeg in
> compressed format over the wire, it just slows down. If you cannot
> configure it to exclude those file-types from compression better
> switch of gzip completely.

Hmmm. I'm going to x-post this to the IIS group because I am not sure
if it's an IIS or IE issue.

I checked the metabase for IIS and .ZIP is not configured as an
extension for the Gzip compression scheme. But, if I disable static and
dynamic compression on the web service, the file now downloads normally
using IE7.

What was configured was:
Right-click Web Sites in IIS Admin tool, Service Tab, Compress
Application files, Compress static file. 100MB max size for temp
directory.

Now both of these are deselected, the file downloads properly. It'd be
interesting to see if your proxy access is now ok? The configuration
remained on from when I was experimenting with Windows Sharepoint
Services. I had added some office document extensions to the metabase
to speed thier download through IIS.

> and why is IE
> > not ungzipping it before it is saved?
>
> That's a good question. And the next question would be: do other
> browsers and your download manager do it correctly or do they simply
> not get those double-zipped files?
> IE may get confused by the fact that the whole thing is
> "double-zipped". If you look at the headers it's possible there is
> no much difference whether you send a zipped file or if you send a
> zipped file gzipped. In both cases you can have a Content-Encoding:
> gzip or deflate, although one file is "double-zipped" and the other
> is not. e.g. I think I remember that Apache will send a file with
> .zip suffix as "Content-Encoding: gzip".

I'm not sure if mime type have anything to do with this. IIS is
currently using this for zip files:
application/x-zip-compressed

> Anyway, good to know that you found the reason, it's an interesting
> finding.

Thanks for the hints!

Just for anyone new, here's the summary.

Original problem was IE7 was downloading a ZIP file which seemed to be
corrupt. Firefox 2.0 and Free Download Manager could both download the
file. After investigation, it was discovered that the file was not
corrupt but contained the zip file in a gzipped file, but using the
same name and extension.

Another poster commented to the thread that it appeared IIS was doing
something funny with chunked encoding and was not viewable through a
squid proxy.

Oops. My x-Post didn't work.
--
ATB,
Karl.

Re: IIS\IE leaving a ZIP file GZIPed on download by David

David
Wed Nov 29 18:09:43 CST 2006

Common confusion. This is a browser issue.

I'll post a blog entry about this topic later, discuss the details of
how compression works and is configured, and hopefully help one
understand what's going on and how to address it.


//David
http://w3-4u.blogspot.com
http://blogs.msdn.com/David.Wang
//



Karl Foley wrote:
> Kai Schaetzl wrote:
>
> > > Now, why the heck is IIS Gzipping and Chunking a file,
> >
> > because it is configured to do so. I thought you were aware that it
> > sends gzipped and I didn't know it's doing that for zipped files as
> > well. So I didn't mention it. You should configure the server to not
> > gzip any binary files. There is no use to send zip, gif or jpeg in
> > compressed format over the wire, it just slows down. If you cannot
> > configure it to exclude those file-types from compression better
> > switch of gzip completely.
>
> Hmmm. I'm going to x-post this to the IIS group because I am not sure
> if it's an IIS or IE issue.
>
> I checked the metabase for IIS and .ZIP is not configured as an
> extension for the Gzip compression scheme. But, if I disable static and
> dynamic compression on the web service, the file now downloads normally
> using IE7.
>
> What was configured was:
> Right-click Web Sites in IIS Admin tool, Service Tab, Compress
> Application files, Compress static file. 100MB max size for temp
> directory.
>
> Now both of these are deselected, the file downloads properly. It'd be
> interesting to see if your proxy access is now ok? The configuration
> remained on from when I was experimenting with Windows Sharepoint
> Services. I had added some office document extensions to the metabase
> to speed thier download through IIS.
>
> > and why is IE
> > > not ungzipping it before it is saved?
> >
> > That's a good question. And the next question would be: do other
> > browsers and your download manager do it correctly or do they simply
> > not get those double-zipped files?
> > IE may get confused by the fact that the whole thing is
> > "double-zipped". If you look at the headers it's possible there is
> > no much difference whether you send a zipped file or if you send a
> > zipped file gzipped. In both cases you can have a Content-Encoding:
> > gzip or deflate, although one file is "double-zipped" and the other
> > is not. e.g. I think I remember that Apache will send a file with
> > .zip suffix as "Content-Encoding: gzip".
>
> I'm not sure if mime type have anything to do with this. IIS is
> currently using this for zip files:
> application/x-zip-compressed
>
> > Anyway, good to know that you found the reason, it's an interesting
> > finding.
>
> Thanks for the hints!
>
> Just for anyone new, here's the summary.
>
> Original problem was IE7 was downloading a ZIP file which seemed to be
> corrupt. Firefox 2.0 and Free Download Manager could both download the
> file. After investigation, it was discovered that the file was not
> corrupt but contained the zip file in a gzipped file, but using the
> same name and extension.
>
> Another poster commented to the thread that it appeared IIS was doing
> something funny with chunked encoding and was not viewable through a
> squid proxy.
>
> Oops. My x-Post didn't work.
> --
> ATB,
> Karl.


Re: IIS\IE leaving a ZIP file GZIPed on download by Karl

Karl
Fri Dec 01 11:44:11 CST 2006

David Wang wrote:

> Common confusion. This is a browser issue.
>
> I'll post a blog entry about this topic later, discuss the details of
> how compression works and is configured, and hopefully help one
> understand what's going on and how to address it.

Cool, I'l subscribe to your RSS feed now! :)