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The VCDIFF Generic Differencing and Compression Data Format (RFC3284)

IP.com Disclosure Number: IPCOM000008641D
Original Publication Date: 2002-Jun-01
Included in the Prior Art Database: 2002-Jul-01
Document File: 30 page(s) / 64K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. Korn: AUTHOR [+4]

Abstract

This memo describes VCDIFF, a general, efficient and portable data format suitable for encoding compressed and/or differencing data so that they can be easily transported among computers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 6% of the total text.

Network Working Group                                            D. Korn

Request for Comments: 3284                                     AT&T Labs

Category: Standards Track                                   J. MacDonald

                                                             UC Berkeley

                                                                J. Mogul

                                                 Hewlett-Packard Company

                                                                   K. Vo

                                                               AT&T Labs

                                                               June 2002

      The VCDIFF Generic Differencing and Compression Data Format

Status of this Memo

   This document specifies an Internet standards track protocol for the

   Internet community, and requests discussion and suggestions for

   improvements.  Please refer to the current edition of the "Internet

   Official Protocol Standards" (STD 1) for the standardization state

   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This memo describes VCDIFF, a general, efficient and portable data

   format suitable for encoding compressed and/or differencing data so

   that they can be easily transported among computers.

Korn, et. al.               Standards Track                     [Page 1]

RFC 3284                         VCDIFF                        June 2002

Table of Contents

    1.  Executive Summary ...........................................  2

    2.  Conventions .................................................  4

    3.  Delta Instructions ..........................................  5

    4.  Delta File Organization .....................................  6

    5.  Delta Instruction Encoding .................................. 12

    6.  Decoding a Target Window .................................... 20

    7.  Application-Defined Code Tables ............................. 21

    8.  Performance ................................................. 22

    9.  Further Issues .............................................. 24

   10.  Summary ..................................................... 25

   11.  Acknowledgements ............................................ 25

   12.  Security Considerations ..................................... 25

   13.  Source Code Availability .................................... 25

   14.  Intellectual Property Rights ................................ 26

   15.  IANA Considerations ......................................... 26

   16.  References .................................................. 26

   17.  Authors' Addresses .......................................... 28

   18.  Full Copyright Statement .................................... 29

1.  Executive Summary

   Compression and differencing techniques can greatly improve storage

   and transmission of files and file versions.  Since files are often

   transported across machines with distinct architectures and

   performance characteristics, such data should be encoded in a form

   that is portable and can be decoded with little or no knowledge of

   the encoders.  This document describes Vcdiff, a compact portable

   encoding format designed for these purposes.

   Data differencing is the process of computing a compact and

   invertible encoding of a "target file" given a "source file".  Data

   compression is similar, but without the use of source data.  The UNIX

   utilities diff, compress, and gzip are well-known examples of data

   differencing and compression tools.  For data differencing, the

   computed encoding is called...