Error log executing scripts?

2002-01-04 Thread Magnús Þór Jónsson 

Hello,
I was wondering if there is any way of making the error log in Apache to
execute a script when an error is occurred, perhaps instead of writing the
error directly to the log.

For example, if there is a image missing Apache excutes a script that
generates a replacement image?

Thanx in advance
Maggi
[EMAIL PROTECTED]

Re: Error log executing scripts?

2002-01-04 Thread Geoffrey Young 

Magnús Þór Jónsson wrote:
 
 Hello,
 I was wondering if there is any way of making the error log in Apache to
 execute a script when an error is occurred, perhaps instead of writing the
 error directly to the log.
 
 For example, if there is a image missing Apache excutes a script that
 generates a replacement image?

well, you can do just about anything you want :)

however, althoughit is possible to intercept the actual errors Apache
(and mod_perl) generates, it is rather complex, and really not the
proper approach here.

the better way is to just write your own handler to add the logic you
are seeking.

for instance, you could write a PerlFixupHandler that

$r-filename('/some/other/file') unless -e $r-finfo;

or whatnot.

if you want a script to run, you could replace the $r-filename('foo')
call with something like

$r-set_handlers(PerlHandler = 'My::ImageGenerating::Package');
$r-handler('perl-script');

or some combination that changed $r-uri if you wanted to use a
Registry script I suppose.

HTH

--Geoff

RE: Error log executing scripts?

2002-01-04 Thread Matt Sergeant 

 -Original Message-
 From: Geoffrey Young [mailto:[EMAIL PROTECTED]]
 
 Magnús Þór Jónsson wrote:
  
  Hello,
  I was wondering if there is any way of making the error log 
 in Apache to
  execute a script when an error is occurred, perhaps instead 
 of writing the
  error directly to the log.
  
  For example, if there is a image missing Apache excutes a 
 script that
  generates a replacement image?
 
 well, you can do just about anything you want :)
 
 however, althoughit is possible to intercept the actual errors Apache
 (and mod_perl) generates, it is rather complex, and really not the
 proper approach here.

Really? I would have thought it could make an interesting caching technique
- on a 404 you try and generate the file, and store in that slot in the
filesystem. A cache cleanup daemon runs to clean out TTL'd files.

Warning: don't try and implement this in a commercial application - it's
patented by vignette.

Matt.

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Re: Error log executing scripts?

2002-01-04 Thread Geoffrey Young 


 
  however, althoughit is possible to intercept the actual errors Apache
  (and mod_perl) generates, it is rather complex, and really not the
  proper approach here.
 
 Really? I would have thought it could make an interesting caching technique
 - on a 404 you try and generate the file, and store in that slot in the
 filesystem. A cache cleanup daemon runs to clean out TTL'd files.

well, I thought he meant by intercepting the actual writes to the
error_log.

Tatushiro actually has an interesting module on CPAN -
http://cpan.valueclick.com/modules/by-module/Apache/Apache-No404Proxy-0.03.tar.gz

it uses a google cache to display 404s (much to google's dismay I
think :)

 
 Warning: don't try and implement this in a commercial application - it's
 patented by vignette.

dirty-box/clean-box :)

--Geoff

Re: Error log executing scripts?

2002-01-04 Thread Geoffrey Young 


 Tatushiro

er, Tastuhiko I mean.  (sorry :)

--Geoff

Re: Error log executing scripts?

2002-01-04 Thread Paul Lindner 

On Fri, Jan 04, 2002 at 01:13:37PM -, Matt Sergeant wrote:
   Hello,
   I was wondering if there is any way of making the error log 
  in Apache to
   execute a script when an error is occurred, perhaps instead 
  of writing the
   error directly to the log.

There is a way to redirect errors to your own code.  It's not pretty.

You can see some example code that does this at
http://www.modperlcookbook.org/code/ch16/

You can also download an example module that uses this code to
intercept error log entries and post them to an IRC channel.  Nothing
like real-time errors to keep you on your toes :)

You can now read that entire chapter (and two others) online at

  http://www.modperlcookbook.org/chapters.html

Enjoy!

   For example, if there is a image missing Apache excutes a 
  script that
   generates a replacement image?

In this case you're talking about a different type of error condition.
As Matt and Geoff mentioned you can use an ErrorDocument script that
runs whenever this condition exists.  This does not handle other output
that flows into your error_log.

  well, you can do just about anything you want :)
  
  however, althoughit is possible to intercept the actual errors Apache
  (and mod_perl) generates, it is rather complex, and really not the
  proper approach here.
 
 Really? I would have thought it could make an interesting caching technique
 - on a 404 you try and generate the file, and store in that slot in the
 filesystem. A cache cleanup daemon runs to clean out TTL'd files.

Check out Apache::CacheContent - it implements something similar,
available on CPAN or at http://www.modperlcookbook.org/code.html

 Warning: don't try and implement this in a commercial application - it's
 patented by vignette.

Hmmm, I implemented something like this in the early 90s...  Long
before vignette was even around..


-- 
Paul Lindner[EMAIL PROTECTED]   | | | | |  |  |  |   |   |

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