http2文档报文及分析

[Docs] [txt|pdf|xml] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits] [IPR] Versions: (draft-mbelshe-httpbis-spdy) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 HTTPbis Working Group M. Belshe Internet-Draft Twist Intended status: Standards Track R. Peon Expires: August 15, 2015 Google, Inc M. Thomson, Ed. Mozilla February 11, 2015 Hypertext Transfer Protocol version 2 draft-ietf-httpbis-http2-17 Abstract This specification describes an optimized expression of the semantics of the Hypertext Transfer Protocol (HTTP). HTTP/2 enables a more efficient use of network resources and a reduced perception of latency by introducing header field compression and allowing multiple concurrent exchanges on the same connection. It also introduces unsolicited push of representations from servers to clients. This specification is an alternative to, but does not obsolete, the HTTP/1.1 message syntax. HTTP's existing semantics remain unchanged. Editorial Note (To be removed by RFC Editor) Discussion of this draft takes place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org), which is archived at [1]. Working Group information can be found at [2]; that specific to HTTP/2 are at [3]. The changes in this draft are summarized in Appendix B. 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 http://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." Belshe, et al. Expires August 15, 2015 [Page 1] Internet-Draft HTTP/2 February 2015 This Internet-Draft will expire on August 15, 2015. Copyright Notice Copyright (c) 2015 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 (http://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 . . . . . . . . . . . . . . . . . . . . . . . . 4 2. HTTP/2 Protocol Overview . . . . . . . . . . . . . . . . . . 5 2.1. Document Organization . . . . . . . . . . . . . . . . . . 6 2.2. Conventions and Terminology . . . . . . . . . . . . . . . 6 3. Starting HTTP/2 . . . . . . . . . . . . . . . . . . . . . . . 7 3.1. HTTP/2 Version Identification . . . . . . . . . . . . . . 8 3.2. Starting HTTP/2 for "http" URIs . . . . . . . . . . . . . 9 3.2.1. HTTP2-Settings Header Field . . . . . . . . . . . . . 10 3.3. Starting HTTP/2 for "https" URIs . . . . . . . . . . . . 11 3.4. Starting HTTP/2 with Prior Knowledge . . . . . . . . . . 11 3.5. HTTP/2 Connection Preface . . . . . . . . . . . . . . . . 11 4. HTTP Frames . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1. Frame Format . . . . . . . . . . . . . . . . . . . . . . 13 4.2. Frame Size . . . . . . . . . . . . . . . . . . . . . . . 14 4.3. Header Compression and Decompression . . . . . . . . . . 14 5. Streams and Multiplexing . . . . . . . . . . . . . . . . . . 15 5.1. Stream States . . . . . . . . . . . . . . . . . . . . . . 16 5.1.1. Stream Identifiers . . . . . . . . . . . . . . . . . 21 5.1.2. Stream Concurrency . . . . . . . . . . . . . . . . . 22 5.2. Flow Control . . . . . . . . . . . . . . . . . . . . . . 23 5.2.1. Flow Control Principles . . . . . . . . . . . . . . . 23 5.2.2. Appropriate Use of Flow Control . . . . . . . . . . . 24 5.3. Stream priority . . . . . . . . . . . . . . . . . . . . . 25 5.3.1. Stream Dependencies . . . . . . . . . . . . . . . . . 25 5.3.2. Dependency Weighting . . . . . . . . . . . . . . . . 26 5.3.3. Reprioritization . . . . . . . . . . . . . . . . . . 27 5.3.4. Prioritization State Management . . . . . . . . . . . 27 5.3.5. Default Priorities . . . . . . . . . . . . . . . . . 29 5.4. Error Handling . . . . . . . . . . . . . . . . . . . . . 29 Belshe, et al. Expires August 15, 2015 [Page 2] Internet-Draft HTTP/2 February 2015 5.4.1. Connection Error Handling . . . . . . . . . . . . . . 29 5.4.2. Stream Error Handling . . . . . . . . . . . . . . . . 30 5.4.3. Connection Termination . . . . . . . . . . . . . . . 30 5.5. Extending HTTP/2 . . . . . . . . . . . . . . . . . . . . 30 6. Frame Definitions . . . . . . . . . . . . . . . . . . . . . . 31 6.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . . . 31 6.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . . . 33 6.3. PRIORITY . . . . . . . . . . . . . . . . . . . . . . . . 35 6.4. RST_STREAM . . . . . . . . . . . . . . . . . . . . . . . 36 6.5. SETTINGS . . . . . . . . . . . . . . . . . . . . . . . . 37 6.5.1. SETTINGS Format . . . . . . . . . . . . . . . . . . . 38 6.5.2. Defined SETTINGS Parameters . . . . . . . . . . . . . 38 6.5.3. Settings Synchronization . . . . . . . . . . . . . . 40 6.6. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . . . 40 6.7. PING . . . . . . . . . . . . . . . . . . . . . . . . . . 42 6.8. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . . . 43 6.9. WINDOW_UPDATE . . . . . . . . . . . . . . . . . . . . . . 46 6.9.1. The Flow Control Window . . . . . . . . . . . . . . . 47 6.9.2. Initial Flow Control Window Size . . . . . . . . . . 48 6.9.3. Reducing the Stream Window Size . . . . . . . . . . . 49 6.10. CONTINUATION . . . . . . . . . . . . . . . . . . . . . . 49 7. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 50 8. HTTP Message Exchanges . . . . . . . . . . . . . . . . . . . 51 8.1. HTTP Request/Response Exchange . . . . . . . . . . . . . 51 8.1.1. Upgrading From HTTP/2 . . . . . . . . . . . . . . . . 53 8.1.2. HTTP Header Fields . . . . . . . . . . . . . . . . . 53 8.1.3. Examples . . . . . . . . . . . . . . . . . . . . . . 57