Compression Extensions for WebSocket
draft-ietf-hybi-permessage-compression-18

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HyBi Working Group                                            T. Yoshino
Internet-Draft                                              Google, Inc.
Intended status: Standards Track                            May 13, 2014
Expires: November 14, 2014

                  Compression Extensions for WebSocket
               draft-ietf-hybi-permessage-compression-18

Abstract

   This document specifies a framework for creating WebSocket extensions
   that add compression functionality to the WebSocket Protocol.  An
   extension based on this framework compresses the payload data portion
   of non-control WebSocket messages on a per-message basis using
   parameters negotiated during the opening handshake.  This framework
   provides a general method to apply a compression algorithm to the
   contents of WebSocket messages.  For each compression algorithm, an
   extension is defined by specifying parameter negotiation and payload
   transformation algorithm in detail.  This document also specifies one
   specific compression extension using the DEFLATE algorithm.

   Please send feedback to the hybi@ietf.org mailing list.

Status of this Memo

   This Internet-Draft is submitted to IETF 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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 14, 2014.

Copyright Notice

   Copyright (c) 2014 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

Yoshino                 Expires November 14, 2014               [Page 1]
Internet-Draft    Compression Extensions for WebSocket          May 2014

   (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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conformance Requirements and Terminology . . . . . . . . . . .  4
   3.  Complementary Terminology  . . . . . . . . . . . . . . . . . .  5
   4.  WebSocket Per-message Compression Extension  . . . . . . . . .  6
   5.  Extension Negotiation  . . . . . . . . . . . . . . . . . . . .  7
     5.1.  Negotiation Examples . . . . . . . . . . . . . . . . . . .  9
   6.  Framing  . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Compression  . . . . . . . . . . . . . . . . . . . . . . . 11
     6.2.  Decompression  . . . . . . . . . . . . . . . . . . . . . . 12
   7.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . . . 14
   8.  permessage-deflate extension . . . . . . . . . . . . . . . . . 15
     8.1.  Method Parameters  . . . . . . . . . . . . . . . . . . . . 16
       8.1.1.  Context Takeover Control . . . . . . . . . . . . . . . 16
       8.1.2.  Limiting the LZ77 sliding window size  . . . . . . . . 18
       8.1.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . 20
     8.2.  Message Payload Transformation . . . . . . . . . . . . . . 21
       8.2.1.  Compression  . . . . . . . . . . . . . . . . . . . . . 21
       8.2.2.  Decompression  . . . . . . . . . . . . . . . . . . . . 22
       8.2.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . 23
     8.3.  Implementation Notes . . . . . . . . . . . . . . . . . . . 26
     8.4.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . 27
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 28
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 29
     10.1. Registration of the "permessage-deflate" WebSocket
           Extension Name . . . . . . . . . . . . . . . . . . . . . . 29
     10.2. Registration of the "Per-message Compressed" WebSocket
           Framing Header Bit . . . . . . . . . . . . . . . . . . . . 29
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 31
     12.2. Informative References . . . . . . . . . . . . . . . . . . 31
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 32