The Cache-Status HTTP Response Header Field
draft-ietf-httpbis-cache-header-07

Document Type Active Internet-Draft (httpbis WG)
Author Mark Nottingham 
Last updated 2021-01-26
Replaces draft-nottingham-cache-header
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HTTP                                                       M. Nottingham
Internet-Draft                                                    Fastly
Intended status: Standards Track                         26 January 2021
Expires: 30 July 2021

              The Cache-Status HTTP Response Header Field
                   draft-ietf-httpbis-cache-header-07

Abstract

   To aid debugging, HTTP caches often append header fields to a
   response explaining how they handled the request.  This specification
   codifies that practice and updates it to align with 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/
   (https://lists.w3.org/Archives/Public/ietf-http-wg/).

   Working Group information can be found at https://httpwg.org/
   (https://httpwg.org/); source code and issues list for this draft can
   be found at https://github.com/httpwg/http-extensions/labels/cache-
   header (https://github.com/httpwg/http-extensions/labels/cache-
   header).

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 30 July 2021.

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Copyright Notice

   Copyright (c) 2021 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 Field . . . . . . . . .   3
     2.1.  The hit parameter . . . . . . . . . . . . . . . . . . . .   4
     2.2.  The fwd parameter . . . . . . . . . . . . . . . . . . . .   4
     2.3.  The fwd-status parameter  . . . . . . . . . . . . . . . .   5
     2.4.  The ttl parameter . . . . . . . . . . . . . . . . . . . .   6
     2.5.  The stored parameter  . . . . . . . . . . . . . . . . . .   6
     2.6.  The collapsed parameter . . . . . . . . . . . . . . . . .   6
     2.7.  The key parameter . . . . . . . . . . . . . . . . . . . .   6
     2.8.  The detail parameter  . . . . . . . . . . . . . . . . . .   6
   3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Defining New Proxy-Status Parameters  . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   To aid debugging, HTTP caches often append header fields to a
   response explaining how they handled the request.  Unfortunately, the
   semantics of these headers are often unclear, and both the semantics
   and syntax used vary between implementations.

   This specification defines a new HTTP response header field, "Cache-
   Status" for this purpose.

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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
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