E-Tag for If-None-Match headers in HTTP are not updated for new files

Question

we have a solution with a Module for static files. In elements.xml we would add each file like this

<Module Name="Files" Url="Style Library" RootWebOnly="True">
  <File Path="Files\css\design.css" Url="css/design.css" Type="GhostableInLibrary" />
</Module>

The problem is that when updating the file the E-Tag is not always updated, for instance if we ask for If-None-Match: "{C51DBB4F-B5EE-4826-9960-864EF6FA967C},1" we get 304 NOT MODIFIED, because this is what the old file had, but the new file responds with E-Tag: "{C51DBB4F-B5EE-4826-9960-864EF6FA967C},1" which is the same as the old.

Update:
We do not use CssRegistration

Answer 1

Note also that even for files which are not being updated, SharePoint 2007 had an interesting behaviour around HTTP 304s and anonymous users. You may know that BLOB caching is required with a max-age attribute to ensure that the correct 'expires' header is sent (the first time round) with the files - otherwise the browser re-requests and gets a 304 for every file. In 2007 the bug was that even with this config, 304s would be sent to anonymous users for some libraries (including the Style Library you appear to be using).

I understood (but haven't checked) that this was fixed in 2010, but you might want to be aware of it if you're looking at things in that area.

My post More on optimization, HTTP 304s etc has more info..

Answer 2

File updates via modules aren´t actually updated in SharePoint, you have to update it through code. See my post at http://johanleino.wordpress.com/2009/04/22/howto-handling-file-updates-in-sharepoint/