Compression Extensions for WebSocket
draft-ietf-hybi-permessage-compression-06

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HyBi Working Group                                            T. Yoshino
Internet-Draft                                              Google, Inc.
Intended status: Standards Track                          March 13, 2013
Expires: September 14, 2013

                  Compression Extensions for WebSocket
               draft-ietf-hybi-permessage-compression-06

Abstract

   This document specifies a framework for creating WebSocket extensions
   that add compression functionality to the WebSocket Protocol.
   Extensions based on this framework compress the payload data portion
   of non-control WebSocket messages on per-message basis using a
   specified compression algorithm.  One reserved bit RSV1 in the
   WebSocket frame header is allocated to control application of
   compression for each message.  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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on September 14, 2013.

Copyright Notice

   Copyright (c) 2013 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

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   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.  WebSocket Per-message Compression Extension  . . . . . . . . .  5
   4.  Extension Negotiation  . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Negotiation Examples . . . . . . . . . . . . . . . . . . .  6
   5.  Framing  . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     5.1.  Sending  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     5.2.  Receiving  . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  permessage-deflate extension . . . . . . . . . . . . . . . . .  9
     6.1.  Method Parameters  . . . . . . . . . . . . . . . . . . . . 10
       6.1.1.  Context Takeover Control . . . . . . . . . . . . . . . 10
       6.1.2.  Limiting the LZ77 sliding window size  . . . . . . . . 10
       6.1.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . 11
     6.2.  Payload Data Transformation  . . . . . . . . . . . . . . . 12
       6.2.1.  Compression  . . . . . . . . . . . . . . . . . . . . . 12
       6.2.2.  Decompression  . . . . . . . . . . . . . . . . . . . . 13
       6.2.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . 14
     6.3.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . 17
     6.4.  Implementation Notes . . . . . . . . . . . . . . . . . . . 17
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
     8.1.  Registration of the "permessage-deflate" WebSocket
           Extension Name . . . . . . . . . . . . . . . . . . . . . . 19
     8.2.  Registration of the "Per-message Compressed" WebSocket
           Framing Header Bit . . . . . . . . . . . . . . . . . . . . 19
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
     10.2. Informative References . . . . . . . . . . . . . . . . . . 21
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 22

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1.  Introduction

   This document specifies a framework to apply a compression algorithm
   to octets exchanged over the WebSocket Protocol [RFC6455].  This
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