[users@httpd] Problems with JS, IE 6.0 and mod_deflate

[Simon Werner <si...@gmail.com>]

We are encountering a problem with IE 6.0 SP1 where it seems to have
problems with compressed data being served from the IBM HTTP Server
2.0.47 (Apache).  Using the mod_deflate option to compress static and
dynamic data on the run.



The problem is that the client side will "hang" and do nothing, we are
not sure what it could be but it looks like it is related to the
javascript files not being decompressed properly. The strange thing is
that the problem appears semi-randomly on one client.  We have tested
it on about 5 clients.  When the problem occurred we discovered that
the last line of a javascript file is missing, this line only contains
a closing bracket, }.  However, this file downloads correctly on other
clients and when mod_deflate is OFF.  So when using the built-in
script debugging tool provided with IE (or MS Office?) the execution
works correctly until the last executable point in the file (which is
not the last line), then the client application hangs, although IE is
responding correctly.  This leads me to the assumption that the file
is not decompressed properly on the client or not compressed properly
on the server (unlikely since it only occurs for one client).



Even IBM, the providers of this Apache server are unable to solve the
problem, see http://publib.boulder.ibm.com/httpserv/ihsdiag/deflate_diag.html
.  They reference an Apache module called mod_net_trace, but there are
no other references to it on the web.

On the Apache server we have enabled SSL (mod_ssl), client-side
caching (mod_expires) and compression (mod_deflate).  When we disable
mod_deflate the client will run correctly.  We have not tried
disabling mod_ssl or mod_expires.  Even when we disable compression
for HTML and JS files the problem still occurs.





########################################

# Apache settings for mod_deflate

LoadModule deflate_module modules/mod_deflate.so

<IfModule mod_deflate.c>

  SetOutputFilter DEFLATE



  #the two above compress everything unless excluded below

  SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip dont-vary

  SetEnvIfNoCase Request_URI \.(?:exe|t?gz|zip|bz2|sit|rar)$ no-gzip dont-vary

  SetEnvIfNoCase Request_URI \.pdf$ no-gzip dont-vary

  # Next two lines are just for testing

  SetEnvIfNoCase Request_URI \.js$ no-gzip dont-vary

  SetEnvIfNoCase Request_URI \.html$ no-gzip dont-vary



  DeflateFilterNote ratio

  DeflateCompressionLevel 9

</IfModule>

#########################################



Fixing this issue will help us enormously in providing clients with a
slow network a decent service.



Thank you,

Simon

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Re: [users@httpd] Problems with JS, IE 6.0 and mod_deflate

[Nick Kew <ni...@webthing.com>]

On Friday 14 April 2006 06:54, Simon Werner wrote:
> We are encountering a problem with IE 6.0 SP1 where it seems to have
> problems with compressed data being served from the IBM HTTP Server
> 2.0.47 (Apache).  Using the mod_deflate option to compress static and
> dynamic data on the run.

The obvious suspect is IE, which is known to be incredibly buggy in
dealing with compressed data (that's why mod_deflate has an option
to compress *only* text/html, available for use with BrowserMatch).

A problem that could lead to similar behaviour would be if Apache fails
to signal the end of the data, so the browser hangs on, waiting for more.
That's unlikely in your case (since it's just the one browser, and since
you mention static pages - which presumably implies no suspect modules
implicated), but could be worth testing.  The first example on the
mod_diagnostics page describes precisely this case, and how to
detect it.


-- 
Nick Kew

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[users@httpd] Re: Problems with JS, IE 6.0 and mod_deflate

[Joost de Heer <sa...@xs4all.nl>]

Simon Werner wrote:
> We are encountering a problem with IE 6.0 SP1 where it seems to have
> problems with compressed data being served from the IBM HTTP Server
> 2.0.47 (Apache).

IBM HTTP Server != Apache HTTP Server, It's based on Apache HTTP Server,
with IBM specific stuff thrown in.

Joost


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