| Internet Engineering Task Force (IETF) | C. Krasic |
|---|---|
| Request for Comments: 9204 | M. Bishop |
| Category: Standards Track | Akamai Technologies |
| ISSN: 2070-1721 | A. Frindell, Editor |
This specification defines QPACK: a compression format for efficiently representing HTTP fields that is to be used in HTTP/3. This is a variation of HPACK compression that seeks to reduce head-of-line blocking.
PROPOSED STANDARDThis document has errata.
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9204.
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The QUIC transport protocol ([QUIC-TRANSPORT]) is designed to support HTTP semantics, and its design subsumes many of the features of HTTP/2 ([HTTP/2]). HTTP/2 uses HPACK ([RFC7541]) for compression of the header and trailer sections. If HPACK were used for HTTP/3 ([HTTP/3]), it would induce head-of-line blocking for field sections due to built-in assumptions of a total ordering across frames on all streams.
QPACK reuses core concepts from HPACK, but is redesigned to allow correctness in the presence of out-of-order delivery, with flexibility for implementations to balance between resilience against head-of-line blocking and optimal compression ratio. The design goals are to closely approach the compression ratio of HPACK with substantially less head-of-line blocking under the same loss conditions.
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.
The following terms are used in this document: