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Compression Extensions for WebSocket
draft-ietf-hybi-permessage-compression-20

HyBi Working Group                                            T. Yoshino
Internet-Draft                                              Google, Inc.
Intended status: Standards Track                          March 24, 2015
Expires: September 25, 2015

                  Compression Extensions for WebSocket
               draft-ietf-hybi-permessage-compression-20

Abstract

   This document defines 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 WebSocket data messages on a per-message basis using parameters
   negotiated during the opening handshake.  This framework provides a
   general method for applying a compression algorithm to the contents
   of WebSocket messages.  Each compression algorithm has to be defined
   in a document defining the extension 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
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   This Internet-Draft will expire on September 25, 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

Yoshino                Expires September 25, 2015               [Page 1]
Internet-Draft    Compression Extensions for WebSocket        March 2015

   Provisions Relating to IETF Documents
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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.  General Negotiation Flow . . . . . . . . . . . . . . . . .  9
     5.2.  Negotiation Examples . . . . . . . . . . . . . . . . . . . 10
   6.  Framing  . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     6.1.  Compression  . . . . . . . . . . . . . . . . . . . . . . . 12
     6.2.  Decompression  . . . . . . . . . . . . . . . . . . . . . . 13
   7.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . . . 15
   8.  permessage-deflate extension . . . . . . . . . . . . . . . . . 16
     8.1.  Method Parameters  . . . . . . . . . . . . . . . . . . . . 17
       8.1.1.  Context Takeover Control . . . . . . . . . . . . . . . 17
       8.1.2.  Limiting the LZ77 sliding window size  . . . . . . . . 19
       8.1.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . 21
     8.2.  Message Payload Transformation . . . . . . . . . . . . . . 22
       8.2.1.  Compression  . . . . . . . . . . . . . . . . . . . . . 22
       8.2.2.  Decompression  . . . . . . . . . . . . . . . . . . . . 23
       8.2.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . 24
     8.3.  Implementation Notes . . . . . . . . . . . . . . . . . . . 28
     8.4.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . 28
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 29
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 30
     10.1. Registration of the "permessage-deflate" WebSocket
           Extension Name . . . . . . . . . . . . . . . . . . . . . . 30
     10.2. Registration of the "Per-message Compressed" WebSocket
           Framing Header Bit . . . . . . . . . . . . . . . . . . . . 30
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 31

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