Shibboleth Developers

[Kaspar Brand <>]

> So, my general question is, should I be checking the Etag or the
> Last-Modified header in order to detect changes?

If the server provides an ETag header in his response, then you should
(or MUST, as per RFC 2616, actually) use that one:

>    HTTP/1.1 clients:
> 
>       - If an entity tag has been provided by the origin server, MUST
>         use that entity tag in any cache-conditional request (using If-
>         Match or If-None-Match).

Otherwise you should use If-Modified-Since (provided that the server's
response had a Last-Modified field).

Setting both If-Match/If-None-Match and If-Modified-Since in a request
has an "undefined" result according to the spec.

Kaspar