Re: relax SHOULD send Last-Modified?, was: APPSDIR review of draft-ietf-httpbis-p4-conditional-24

On 4 Nov 2013, at 3:28 pm, Julian Reschke <> wrote:

> On 2013-11-04 07:45, Ray Polk wrote:
>> ...
>> 2) relax SHOULD to MAY for Last-Modified when ETag is also supplied in the following sections:
>> 2.2.1. Generation
>> "An origin server SHOULD send Last-Modified for any selected representation for which a last modification date can be reasonably and consistently determined,"
> > ...
> ...and it continues with...
> "...since its use in conditional requests and evaluating cache freshness ([Part6]) results in a substantial reduction of HTTP traffic on the Internet and can be a significant factor in improving service scalability and reliability..."
> I believe that's the reason why it is a SHOULD.

Yes. This was discussed extensively; it was felt that the benefit to the network was significant enough to include a “social SHOULD.”


Mark Nottingham

Received on Monday, 4 November 2013 23:40:24 UTC