A Static (?) XML file can never receive a 304 Not Modified

[alexkemp9]

Background
Conducting a simple refresh (f5) on a recently downloaded test map page causes only half (10 out of 21) of the files to give a 304 Not Modified.

Some of those files may well be dynamic, but some are clearly static. Because of the wide range of Response Header symptoms + my ignorance these are individual filetype reports to allow those with a working knowledge of the code to decipher it all. Please also note that since these tests the Last-Modified value has been re-enabled & eTag disabled.

The Meat
(probably) a static XML file. This is similar (but different) to the HTML file problem

1 x XML
eg https://www.openstreetmap.org/api/0.6/way/17236956/full

• cache-control: max-age=0, private, must-revalidate
• eTag: none
• Expires: none
• Last-Modified: none
• Request: (cache, but no eTag nor Last-Modified, so no request headers, so no 304)

Related
The tiles supplied by toothless (eg https://b.tile.openstreetmap.org/18/130245/85447.png) are all dynamic yet all have a strong eTag (matched by the If-None-Match) + Expires + Cache-Control and thus get cached + a 304.

Extra
See bottom of this Diary page for fuller details.

[tomhughes]

API responses are not in any way static - they will vary as the underlying object is edited.