Re: Recognizing CGI script responses

[Second try at posting this, first attempt never got past the mailer
 at www10.w3.org....]

Henrik Frystyk Nielsen:
>[Koen Holtman:]
>> Thus, the lack of Last-modified is a means of telling that a response
>> came from a script.

>This doesn't necessarily make it a good thing ;-) You can't and shouldn't
>make any assumptions on the origin of documents from missing headers!

I agree that using the lack of a header to conclude something is
sub-optimal.

However, as long as a there are still many dynamic resources around
that do not return Expires headers, looking at the absence of
Last-modified in deciding not to cache is vastly preferable to doing
nothing (see the message by Ari Luotonen I quoted previously).

>There is no reason to forbid caching of CGI scripts

True, and I don't propose to.  I'm thinking along the lines of
`strongly suggesting' that not caching (or at least always doing a
conditional GET) should be the default behavior for responses that
lack both Expires and Last-modified headers.

In the future, things will hopefully evolve to a state where basing
behavior on the lack of headers is increasingly less necessary.
However, the more I think about these issues, the more I am becoming
convinced that this evolution is currently being stalled by a deadlock
situation.  I'll write some more about this in a few days.

>Henrik Frystyk                                          frystyk@W3.org

Koen.

Received on Thursday, 8 June 1995 12:12:05 UTC