Internet DRAFT - draft-lassey-priority-setting
draft-lassey-priority-setting
HTTP B. Lassey
Internet-Draft Google
Intended status: Standards Track L. Pardue
Expires: January 26, 2020 Cloudflare
July 25, 2019
Declaring Support for HTTP/2 Priorities
draft-lassey-priority-setting-00
Abstract
HTTP/2 provides a prioritization scheme but experience has shown that
implementation support varies. This document defines an HTTP/2
setting that endpoints can use as an affirmative signal to indicate
their support for HTTP/2 Priorities.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on January 26, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. The SETTINGS_ENABLE_HTTP2_PRIORITIES SETTINGS Parameter . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.1. A New HTTP/2 Setting . . . . . . . . . . . . . . . . . . 3
5. Normative References . . . . . . . . . . . . . . . . . . . . 3
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 3
1. Introduction
The HTTP/2 specification defines a priority scheme in [RFC7540],
Section 5.3, which some implementers have opted not to fully support.
The lack of signalling about the status of the implementation has
caused several implementations to implement heuristics to detect when
the clients they are connected to do not support priorities as
defined and take steps to compensate for that. The intent of this
draft is to provide and affirmative signalling mechanism for each
client to communicate whether or not it supports and will use the
priority scheme as defined in [RFC7540], Section 5.3.
2. Terminology
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.
3. The SETTINGS_ENABLE_HTTP2_PRIORITIES SETTINGS Parameter
This document adds a new SETTINGS parameter to those defined by
[RFC7540], Section 6.5.2.
The new parameter name is SETTINGS_ENABLE_HTTP2_PRIORITIES. The
value of the parameter MUST be 0 or 1 to indicate not supporting or
supporting HTTP/2 priorities respectively. If either side sends the
parameter with a value of 0, clients SHOULD NOT send priority frames
and servers SHOULD NOT make any assumptions based on the presence or
lack thereof of priority frames. If both sides send the parameter
with a value of 1, then both parties MAY use HTTP/2 priorities as
they see fit. A sender MUST NOT send the parameter with the value of
0 after previously sending a value of 1. If a client or server does
not send the setting, the peer SHOULD NOT make any assumptions about
its support for HTTP/2 priorities.
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4. IANA Considerations
4.1. A New HTTP/2 Setting
This document registers an entry in the "HTTP/2 Settings" registry
that was established by Section 11.3 of [RFC7540].
Name: SETTINGS_ENABLE_HTTP2_PRIORITIES
Code: 0xTBD
Initial Value: 1
Specification: This document
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Brad Lassey
Google
Email: lassey@chromium.org
Lucas Pardue
Cloudflare
Email: lucaspardue.24.7@gmail.com
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