On Tue, Oct 19, 1999, Jeff Rush wrote:

I'm pulling my hair out here over what is probably a simple HTTP issue. I have a Zope method that stuffs a new image into a Zope Image object, based on the content of the page where the method is called.

Your IMG tags point to the same URL but the actual image contents dynamically change?

The problem is that the image is not updated until I exit the browser, and then flush all of it's caches manually.

This is definitely a browser caching issue.

I've turned off any proxy support, configured Netscape 4.x with the option "Document in cache is compared to document on web site [always]", and even run the 'curl' utility outside of the browser that prints the HTTP headers. The headers show that the modified date is changing, the size is changing (different image sizes), and that there is no expire header. I thought maybe I needed one but noticed that no where in the Zope source code do they use one, and when one of their images is re-uploaded via the /manage_upload, it displays correctly.

Am I missing something simple?

Here's something simple to do: append a "?randomstring" to the end of the SRC of your IMG tags, ie: <IMG SRC="/Images/myimage_gif?<dtml-var randomstuff>"> Here's a little example that should work. This uses a timestamp to mark the IMG SRC (based on Bill's "HowTo Autogenererate an Object ID"): <dtml-call "REQUEST.set('ts', ZopeTime())"> <dtml-call "REQUEST.set('randomstuff',_.str(_.int(ts)))"> <IMG SRC="/Images/myimage_gif?<dtml-var randomstuff>"> This won't help you if you're going to render the Image directly, the usual: <dtml-with Image><dtml-var "myimage_gif.tag(randomstuff)"></dtml-with> just isn't going to work. If anyone knows how to append such a string with the Image.tag method, please let us know :) This is the only "simple" workaround I'm aware of to address this issue. - Ian C. Blenke <icblenke@2c2.com>