[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-wu-netmod-yang-xml-doc-conventions) 00 01 02 03 04 05 06

Internet Architecture Board (IAB)                              K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Best Current Practice                      May 29, 2018
Expires: November 30, 2018


                Handling Long Lines in Artwork in Drafts
                draft-kwatsen-netmod-artwork-folding-00

Abstract

   This document introduces a simple and yet time-proven strategy for
   handling long lines in artwork in drafts using a backslash ('\')
   character where line-folding has occurred.  The strategy works on any
   text based artwork, producing consistent results regardless the
   artwork content.  Using a per-artwork notice, the strategy is both
   self-documenting and enables automated reconstitution of the original
   artwork.

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 https://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."

   This Internet-Draft will expire on November 30, 2018.

Copyright Notice

   Copyright (c) 2018 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
   (https://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



Watsen                  Expires November 30, 2018               [Page 1]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Automated folding of long lines in artwork  . . . . . . .   3
     3.2.  Automated reconstitution of original artwork  . . . . . .   3
   4.  Limitations . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Doesn't work well on graphical artwork  . . . . . . . . .   3
     4.2.  Doesn't work as well as format-specific options . . . . .   4
   5.  Solution  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Folding . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.2.  Unfolding . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  POSIX Shell Script . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Internet drafts many times contain artwork that exceed the 72
   character limit specified by RFC 7994 [RFC7994].  The "xml2rfc"
   utility, in an effort to maintain clean formatting, issues a warning
   whenever artwork lines exceed 69 characters.  According to RFC
   Editor, there is currently no convention in place for how to handle
   long lines, other than clearly indicating that some manipulation has
   occurred.

   This document introduces a simple and yet time-proven strategy for
   handling long lines using a backslash ('\') character where line-
   folding has occurred.  The strategy works on any text based artwork,
   producing consistent results regardless the artwork content.  Using a
   per-artwork notice, the strategy is both self-documenting and enables
   automated reconstitution of the original artwork.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP




Watsen                  Expires November 30, 2018               [Page 2]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Goals

3.1.  Automated folding of long lines in artwork

   Automated folding of long lines is needed in order to support draft
   compilations that entail a) validation of source input files (e.g.,
   YANG, XML, JSON, ABNF, ASN.1) and/or b) dynamic generation of output
   (e.g., tree diagrams) that are stitched into the final draft to be
   submitted.

   Generally, in order for tooling to be able to process input files,
   the files must be in their original/natural state, which may include
   having some long lines.  Thus, these source files need to be modified
   before inclusion in the draft in order to satisfy the line length
   limits.  This modification SHOULD be automated to reduce effort and
   errors resulting from manual effort.

   Similarly, dynamically generated output (e.g., tree diagrams) must
   also be modified, if necessary, in order for the resulting I-D to
   satisfy the line length limits.  When needed, this effort again
   SHOULD be automated to reduce effort and errors resulting from manual
   effort.

3.2.  Automated reconstitution of original artwork

   Automated reconstitution of the original artwork is needed to support
   validation of artwork extracted from drafts.  Already YANG modules
   are extracted from drafts and validated as part of the draft-
   submission process.  Additionally, there has been some discussion
   regarding needing to do the same for examples contained within drafts
   ([yang-doctors-list]).  Thus, it SHOULD be possible to mechanically
   reconstitute artwork in order to satisfy the tooling input parsers.

4.  Limitations

4.1.  Doesn't work well on graphical artwork

   While the solution presented in this document will work on any kind
   of text-based artwork, it is most useful on artwork that represents
   sourcecode (e.g., YANG, XML, JSON, etc.) or, more generally, on
   artwork that has not been laid out in two dimensions (e.g.,
   diagrams).

   The issue regards the readability of the folded artwork in the draft.
   Artwork that is unpredictable is especially susceptible is looking



Watsen                  Expires November 30, 2018               [Page 3]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   bad when folded; falling into this category are most UML diagrams.
   Artwork that is somewhat structured (e.g., YANG tree diagrams
   [RFC8340]) fair better when folded, as the eyes seem to be able to
   still see the vertical lines, even when they are interrupted.

   It is thus NOT RECOMMENDED to use the solution presented in this
   document on graphical artwork.

4.2.  Doesn't work as well as format-specific options

   The solution presented in this document works generically for all
   artwork, as it only views artwork as plain text.  However, various
   formats sometimes have mechanisms that can be used to prevent long
   lines.

   For instance, some source formats allow any quoted string to be
   broken up into substrings separated by a concatenation character
   ('+'), any of which can by on a different line.

   In another example, some languages allow factoring out chucks of code
   out into "functions" or "groupings".  Using such call outs is
   especially helpful when in some deeply-nested code, as it typically
   resets the indentation back to the first column.

   As such, it is RECOMMENDED that authors do as much as possible within
   the selected format to avoid long lines.

5.  Solution

   The following two sections provide the folding and unfolding
   algorithms that MUST be implemented to align with this BCP.

5.1.  Folding

   Scan the artwork to see if any line exceeds the desired maximum.  If
   no line exceeds the desired maximum, exit (this artwork does not need
   to be folded).

   Otherwise, as it is determined the artwork needs to be folded,
   prepend the 3-line header (RFC Ed. please replace XX below with the
   assigned value for this BCP):

   \n[Note: '\' line wrapping added per BCP XX]\n\n

   For each line in the artwork, from top-to-bottom, if the line exceeds
   the desired maximum, then fold the line at the desired column by
   inserting the string "\\n" at the column before the maximum column.
   Note that the spacer is needed to give room for the '\' character.



Watsen                  Expires November 30, 2018               [Page 4]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   Continue in this manner until reaching the end of the artwork.  Note
   that the algorithm naturally addresses the case where the remainder
   of a folded line is still longer than the desired maximum.

5.2.  Unfolding

   Scan the artwork for the above-mentioned header.  If the header is
   not present in the artwork, exit (this artwork does not need to be
   unfolded).

   Remove the 3-line header from the artwork.

   For each line in the artwork, from top-to-bottom, if the line ends in
   "\\n", then remove the "\\n" and then scan the remainder of the line
   to see if it again ends in "\\n", and so on.

   Continue in this manner until reaching the end of the artwork.

6.  Security Considerations

   This BCP has no Security Considerations.

7.  IANA Considerations

   This BCP has no IANA Considerations.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [RFC7994]  Flanagan, H., "Requirements for Plain-Text RFCs",
              RFC 7994, DOI 10.17487/RFC7994, December 2016,
              <https://www.rfc-editor.org/info/rfc7994>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.



Watsen                  Expires November 30, 2018               [Page 5]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   [yang-doctors-list]
              "[yang-doctors] automating yang doctor reviews",
              <https://mailarchive.ietf.org/arch/msg/yang-doctors/
              DCfBqgfZPAD7afzeDFlQ1Xm2X3g>.















































Watsen                  Expires November 30, 2018               [Page 6]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


Appendix A.  POSIX Shell Script

   This non-normative appendix section includes a shell script that can
   both fold and unfold artwork based on the solution presented in this
   document.

   As a testament for the simplicity of this solution, note that at the
   core of the script are the following two one-liners:

   For folding:    gsed "s/\(.\{$foldcol\}\)/\1\\\\\n/"
   For unfolding:  gsed ':x; /\\$/ { N; s/\\\n//; tx }'

   =====START SCRIPT=====

   #!/bin/bash
   #
   # the only reason why /bin/sh isn't being used
   # is because "echo -n" is broken on the Mac.

   print_usage() {
     echo
     echo "Wraps file representing IETF artwork at specified column"
     echo "according to BCP XX.  Note, this routine does nothing if"
     echo "the infile has no lines longer than specified."
     echo
     echo "Usage: $0 [-r] [-c <col>] -i <infile> -o <outfile>"
     echo
     echo "  -c: column to wrap on (default: 69)"
     echo "  -r: reverses the operation"
     echo "  -i: the input filename"
     echo "  -o: the output filename"
     echo "  -h: show this message"
     echo
     echo "Exit status code: zero on success, non-zero otherwise."
     echo
   }


   # global vars, do not edit
   reversed=0
   infile=""
   outfile=""
   maxcol=69  # default, may be overridden by param
   header="\n[Note: '\' line wrapping added per BCP XX]\n\n"


   fold_it() {
     # check if file needs folding



Watsen                  Expires November 30, 2018               [Page 7]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


     grep ".\{$maxcol\}" $infile >> /dev/null 2>&1
     if [ $? -ne 0 ]; then
       # nothing to do
       cp $infile $outfile
       return 1
     fi

     echo -ne "$header" > $outfile
     foldcol=`expr "$maxcol" - 1` # spacer for the inserted '\' char
     gsed "s/\(.\{$foldcol\}\)/\1\\\\\n/" < $infile >> $outfile
     return 0
   }


   unfold_it() {
     # count lines in header
     numlines=`echo -ne "$header" | wc -l`

     # check if file needs unfolding
     echo -ne "$header" > /tmp/header
     head -n $numlines $infile > /tmp/header2
     diff -q /tmp/header /tmp/header2 >> /dev/null
     code=$?
     rm /tmp/header /tmp/header2
     if [ $code -ne 0 ]; then
       # nothing to do
       cp $infile $outfile
       return 1
     fi

     awk "NR>$numlines" $infile > /tmp/wip
     gsed ':x; /\\$/ { N; s/\\\n//; tx }' /tmp/wip > $outfile
     rm /tmp/wip
     return 0
   }


   process_input() {
     while [ "$1" != "" ]; do
       if [ "$1" == "-h" -o "$1" == "--help" ]; then
         print_usage
         exit 1
       fi
       if [ "$1" == "-c" ]; then
         maxcol="$2"
         shift
       fi
       if [ "$1" == "-r" ]; then



Watsen                  Expires November 30, 2018               [Page 8]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


         reversed=1
       fi
       if [ "$1" == "-i" ]; then
         infile="$2"
         shift
       fi
       if [ "$1" == "-o" ]; then
         outfile="$2"
         shift
       fi
       shift
     done

     if [ -z "$infile" ]; then
       echo "error: infile parameter missing."
       exit 1
     fi

     if [ -z "$outfile" ]; then
       echo "error: outfile parameter missing."
       exit 1
     fi

     if [ ! -f "$infile" ]; then
       echo "error: infile \"$infile\" does not exist."
       exit 1
     fi

     if [ -f "$outfile" ]; then
       echo "warning: outfile \"$outfile\" already exists."
     fi
   }


   main() {
     if [ "$#" == "0" ]; then
        print_usage
        exit 1
     fi

     process_input $@

     if [[ $reversed -eq 0 ]]; then
       fold_it
     else
       unfold_it
     fi
     exit 0



Watsen                  Expires November 30, 2018               [Page 9]


Internet-Draft  Handling Long Lines in Artwork in Drafts        May 2018


   }

   main "$@"

   =====END SCRIPT=====

Acknowledgements

   The authors thank the RFC Editor for confirming that there are no set
   convention today for handling long lines in artwork.

Author's Address

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net


































Watsen                  Expires November 30, 2018              [Page 10]


Html markup produced by rfcmarkup 1.127, available from https://tools.ietf.org/tools/rfcmarkup/