[Zope] Possible incorrect http header "Last-Modified" with ExternalFile

[BLOCKLEY Adrian]

Hi,

I am not sure if this is the right place to ask this but I think I have 
found a possible problem with ExternalFile not returning the correct 
http header Last-Modified when linking to a gif file. This is in turn 
causing problems with caching.

For example, the file weekly.gif is stored as an externalfile object in 
our web server. Using wget to retrieve the header information returns 
the following:

wget -S 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/weekly.gif
--15:57:35-- 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/weekly.gif
            => `weekly.gif.22'
Resolving aqmpweb.environ.wa.gov.au... done.
Connecting to aqmpweb.environ.wa.gov.au[192.168.1.3]:80... connected.
HTTP request sent, awaiting response...
  1 HTTP/1.1 200 OK
  2 Date: Thu, 19 Aug 2004 08:13:11 GMT
  3 Server: Apache/1.3.28 (Linux/SuSE)
  4 Accept-Ranges: none
  5 X-Powered-By: Zope (www.zope.org), Python (www.python.org)
  6 Content-Length: 22369
  7 Last-Modified: Thu, 01 Jan 1970 00:00:00 GMT
  8 Keep-Alive: timeout=15, max=100
  9 Connection: Keep-Alive
10 Content-Type: image/gif

100%[======================================================>] 22,369 
     21.40K/s    ETA 00:00

Last-modified header invalid -- time-stamp ignored.


Repeating for another file that is not an image but stored as an 
externalFile object returns the following:
wget -S 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/aqr.html
--16:30:39-- 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/aqr.html
            => `aqr.html.1'
Resolving aqmpweb.environ.wa.gov.au... done.
Connecting to aqmpweb.environ.wa.gov.au[192.168.1.3]:80... connected.
HTTP request sent, awaiting response...
  1 HTTP/1.1 200 OK
  2 Date: Thu, 19 Aug 2004 08:46:16 GMT
  3 Server: Apache/1.3.28 (Linux/SuSE)
  4 X-Powered-By: Zope (www.zope.org), Python (www.python.org)
  5 Content-Length: 3251
  6 Keep-Alive: timeout=15, max=100
  7 Connection: Keep-Alive
  8 Content-Type: text/html

100%[======================================================>] 3,251 
      1.55M/s    ETA 00:00



Repeating with an image that is not an externalfile object returns the 
following:
wget -S 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/mapperth.g
if
--16:32:00-- 
http://aqmpweb.environ.wa.gov.au/aq2/Current_Air_Quality/AQ_index/mapperth.g
if
            => `mapperth.gif.2'
Resolving aqmpweb.environ.wa.gov.au... done.
Connecting to aqmpweb.environ.wa.gov.au[192.168.1.3]:80... connected.
HTTP request sent, awaiting response...
  1 HTTP/1.1 200 OK
  2 Date: Thu, 19 Aug 2004 08:47:37 GMT
  3 Server: Apache/1.3.28 (Linux/SuSE)
  4 Accept-Ranges: bytes
  5 Cache-Control: max-age=3600
  6 Expires: Thu, 19 Aug 2004 09:47:37 GMT
  7 X-Powered-By: Zope (www.zope.org), Python (www.python.org)
  8 Content-Length: 11160
  9 Last-Modified: Tue, 18 May 2004 06:49:30 GMT
10 Keep-Alive: timeout=15, max=100
11 Connection: Keep-Alive
12 Content-Type: image/gif

100%[======================================================>] 11,160 
      5.42K/s    ETA 00:00

16:32:02 (5.42 KB/s) - `mapperth.gif.2' saved [11160/11160]



It is not clear to me why gif images stored ExternalFile objects return 
a date of Thu, 01 Jan 1970 00:00:00 GMT each time. It looks like the 
time field is being set to 0 somewhere but my limited python and zope 
experience has not enabled me to locate whether the problems are in 
Zope, ExternalFile or maybe some hidden problem with our Zope configuration.

If you have any suggestions as to where the problem may lie I would be 
most appreciative.

By the way we are using:

  Zope Version
(Zope 2.6.1 (source release, python 2.1, linux2) [SuSE Linux], python 
2.1.3, linux2)

Python Version
2.1.3 (#1, Sep 23 2003, 23:06:30) [GCC 3.3.1 (SuSE Linux)]
System Platform
linux2

Cheers

Adrian Blockley

=======================================================================
Adrian Blockley  
Western Australian Department of Environment
123 Adelaide Terrace 
East Perth

Mailing address:
PO Box K822
Perth W.A. 6842

Ph:  +61 8 9278 0692
Fax: +61 8 9278 0639
=======================================================================
 
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