Summary: EnableIMSCaching trouble updates
Created: 2004-10-17 16:07
Status: Closed
Category: Site config problem
From: PRZ
Priority: 31
Version: 2.0 Devel13
OS: Linux, PHP4.3.8

Description: I have an installation of my site on a very slow provider, where i have enabled IMS caching. This work without trouble.

To test, i have make a complete copy of this site at another provider. Though, with this new faster provider :

  • With Netscape 7.1, when i edit and save, the page is not updated, i have to reload it to see the modifications.
  • With IE 6.0, the update after an edit is fine.
When i disable the caching, the edit update works fine.

Here is the troublesome site , with caching enabled :

[(approve links) edit diff]

PRZ October 17, 2004, at 04:09 PM

First, let me confirm that the problem does indeed exist on the site above. That said, I think the problem must be a configuration problem on the host and not a problem with PmWiki. First, I grabbed the http headers from accessing the above page:

HTTP/1.1 200 OK
Date: Thu, 21 Oct 2004 14:56:20 GMT
Server: Apache
X-Powered-By: PHP/4.3.8
Set-Cookie: PHPSESSID=60f5cbf21846bae45a44c5246777ab57; path=/
Expires: Tue, 01 Jan 2002 00:00:00 GMT
Cache-Control: no-cache
Pragma: no-cache
Last-Modified: dim, 17 oct 2004 09:31:12 GMT
Connection: close
Content-Type: text/html; charset=iso-8859-1;

The problem is the "Last-Modified:" header. First, the date/time itself in this header is incorrect, with IMS caching enabled the header should be the date/time of the last modified page (which would have been my modification on Oct 21). Can you see what the modification time and permissions are for the wiki.d/.lastmod file?

Second, the format of the header itself is wrong--RFC 1123 says that days and months must be specified in English format. This is a bug in PmWiki, to be fixed in 2.0.devel15.

Let me know (here or via email) what you find out about the .lastmod file.


Actually, after thinking about it a bit further, I'm fairly sure the problem is the permissions on the wiki.d/.lastmod file. Try removing that file and see if it fixes the caching problems.


I have deleted the site before seing your message, and a fresh install was working finely.
Though, i've made a copy of the .lastmod file from the initial install (permission 666) to Windows, then a copy from Windows to the fresh site. the permission of the file as copied from Windows then became 644, and i have reproduced the bug, say no page update.

Setting back the permissions of the .lastmod file to 666, and the page update was back.

So i think this is a warning to set when making a copy/restoration of a site.

--PRZ November 01, 2004, at 07:52 AM