The Cache-Status HTTP Response Header
draft-ietf-httpbis-cache-header-02
HTTP M. Nottingham
Internet-Draft Fastly
Intended status: Standards Track November 4, 2019
Expires: May 7, 2020
The Cache-Status HTTP Response Header
draft-ietf-httpbis-cache-header-02
Abstract
To aid debugging, HTTP caches often append headers to a response
detailing how they handled the request. This specification codifies
that practice and updates it for HTTP's current caching model.
Note to Readers
_RFC EDITOR: please remove this section before publication_
Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/ [1].
Working Group information can be found at https://httpwg.org/ [2];
source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/cache-header [3].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 7, 2020.
Nottingham Expires May 7, 2020 [Page 1]
Internet-Draft Cache-Status Header November 2019
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. The Cache-Status HTTP Response Header . . . . . . . . . . . . 3
2.1. The fwd parameter . . . . . . . . . . . . . . . . . . . . 4
2.2. The fwd-res parameter . . . . . . . . . . . . . . . . . . 4
2.3. The fwd-stored parameter . . . . . . . . . . . . . . . . 5
2.4. The res-fresh parameter . . . . . . . . . . . . . . . . . 5
2.5. The cache-fresh parameter . . . . . . . . . . . . . . . . 5
2.6. The collapse-hit parameter . . . . . . . . . . . . . . . 5
2.7. The collapse-wait parameter . . . . . . . . . . . . . . . 5
2.8. The key parameter . . . . . . . . . . . . . . . . . . . . 6
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Normative References . . . . . . . . . . . . . . . . . . 7
5.2. Informative References . . . . . . . . . . . . . . . . . 8
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
To aid debugging, HTTP caches often append headers to a response
detailing how they handled the request.
Unfortunately, the semantics of these headers are often unclear, and
both the semantics and syntax used vary greatly between
implementations.
This specification defines a single, new HTTP response header field,
"Cache-Status" for this purpose.
Nottingham Expires May 7, 2020 [Page 2]
Internet-Draft Cache-Status Header November 2019
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses ABNF as defined in [RFC5234], along with the "%s"
extension for case sensitivity defined in [RFC7405].
2. The Cache-Status HTTP Response Header
Show full document text