Internet-Draft                                                Ryan Moats
draft-ietf-urn-ietf-05.txt
draft-ietf-urn-ietf-06.txt                                          AT&T
Expires in six months                                           May                                          June 1998

                   A URN Namespace for IETF Documents
                  Filename: draft-ietf-urn-ietf-05.txt draft-ietf-urn-ietf-06.txt

Status of This Memo

      This document is an Internet-Draft.  Internet-Drafts are working
      documents of the Internet Engineering Task Force (IETF), its
      areas, and its working groups.  Note that other groups may also
      distribute working documents as Internet-Drafts.

      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.''

      To view learn the entire list of current Internet-Drafts, status of any Internet-Draft, please check
      the "1id-abstracts.txt" ``1id-abstracts.txt'' listing contained in the Internet-Drafts Internet-
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      (Northern Europe), ftp.nis.garr.it (Southern Europe), nic.nordu.net
      (Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org ds.internic.net (US East
      Coast), or ftp.isi.edu (US West Coast).

Abstract

   A system for Uniform Resource Names (URNs) must be capable of
   supporting new naming systems.  As an example of proposing a new
   namespace, this document proposes the "ietf" 'ietf' namespace.  This
   namespace consists of the RFC family of documents (RFCs, STDs, FYIs,
   and BCPs) developed by the IETF and published by the RFC editor and
   the minutes of working groups (WG) and birds of a feather (BOF)
   meetings that occur during IETF conferences.  Both the current URN
   framework and URN syntax support this namespace.

0.1 Changes from -02

   This document has been restructured to use the template proposed in
   draft-ietf-urn-nid-req-03.txt.  Example Perl scripts for resolving
   this namespace have been supplied in an Appendix.

0.2 Changes from -03

   Text was added to the template clarifying persistence and uniqueness.
   Support for the BCP document series added to the examples and the
   ABNF.

0.3 Changes from -04

   More clarifications for the persistence section.  In addition,
   cleaned up some typos and ensured that the Appendix examples are
   functional

0.4 Changes from -05

   Based on a number of requests, i-ds have been added to the structure
   and resolvers. In addition, some examples have been added.

1. Introduction

   This document proposes the "ietf" namespace, which consists of the
   RFC family of documents (RFCs, STDs, FYIs, and BCPs) developed by the
   IETF and published by the RFC editor and the minutes of working
   groups (WG) and birds of a feather (BOF) meetings that occur during
   IETF conferences.

   The namespace specification is for a formal namespace.

2. Specification Template

        Namespace ID:

                "ietf" requested.

        Declared registrant of the namespace:

                Ryan Moats
                jayhawk@att.com

        Declaration of structure:

                The identifier has the following ABNF [2] specification:

                NSS = (family ":" number) / ("mtg-" number "-" wgbofname)
                      ( "id:" name)
                family = "rfc" / "std" / "fyi" / "bcp"
                number = 1*DIGIT
                wgbofname = 1*LETDIGIT
                name =  id draft designation with "draft-" and trailing
                        type removed (e.g. ietf-urn-ietf-06)
                LETDIGIT = DIGIT / %x41-%x5a / %x61-%x7a
                DIGIT = %x30-%x39

                If the IESG (or it successor) adds a new document
                series, this ABNF specification will need to be
                updated.  Further, if a working group or BOF is
                created that used characters outside the range of this
                ABNF specification, this specification will need to be
                updated.  Any system intended to resolve names for
                this namespace should be written with the awareness
                that this could occur at any time.

        Identifier uniqueness considerations:

                Because the rfc-editor assigns the RFC number uniquely
                these URNs are unique.  Since the mapping between RFCs
                and other rfc-editor document series (STDs, FYIs or
                BCPs) is not necessarily one-to-one, uniqueness of
                STDs, FYIs and BCPs are defined based on the document
                mappings maintained by the RFC Editor (the index files
                "rfc-index.txt", "fyi-index.txt", "bcp-index.txt" and "bcp-index.txt",
                "std-index.txt") are defined to be the definitive
                statement of the assignment of RFC Family URNs in this
                namespace.  The meeting minutes portion of the
                namespace is guaranteed unique because the URN
                includes the sequence number of the IETF conference.
                The document mapping maintained by the Internet Drafts
                editor ("1id-abstracts.txt") is defined as the
                definitive statement of the assignment of URNs for
                the internet draft portion of this namespace.

        Identifier persistence considerations:

                Persistence of the URNs of this namespace is
                independent of the mutability of the underlying
                documents.  A URN once assigned will never be
                reassigned to a different resource; the assignment is
                persistent and immutable.  Distinct from this, the
                resources identified as RFCs are immutable, whereas
                the other sorts of documents, STDs, FYIs, and BCPs are
                not.  They may be composites of one or more RFCs and
                the set of RFCs that comprise them may change with
                time.  It is important to note that this mutability of
                some resources is independent of the immutability of
                URN assignment to a resource.

        Process of identifier assignment:

                Assignment of URNs from this namespace occurs in two
                ways.  The first is when a new RFC, FYI, STD or BCP is
                passed by the IESG and published by the RFC
                Editor. This new document will have a new series
                number and will therefore define a new URN.  The
                document mappings maintained by the RFC Editor (the
                index files "rfc-index.txt", "fyi-index.txt",
                "bcp-index.txt" and "std-index.txt") are defined to be
                the definitive statement of the assignment of RFC
                Family URNs in this namespace.

                The second way a URN is assigned is when a working
                group or birds of a feather files meeting minutes as
                part of an IETF conference.  The list of minutes
                maintained by the IETF for each working group and
                conference in the subtree pointed at by the URL
                ftp://ietf.org/ietf/ is considered the definitive
                assignment of URNs for working group or birds of a
                feather minutes.

                The third way a URN is assigned is through the
                publication of a new internet-draft by the Internet
                Draft Editor.  This draft will have a distinct name
                (and version number) and therefore defined a new URN.
                The document mapping maintained by the Internet Drafts
                editor ("1id-abstracts.txt") is defined as the
                definitive statement of the assignment of URNs for
                this portion of the namespace.

        Process of identifier resolution:

                A mirrored copy of the underlying documentation is
                required to resolve these URNs.  Resolution via
                HTTP is accomplished by a set of simple Perl cgi-bin
                scripts presented in Appendix A.

        Rules for Lexical Equivalence:

                The entire URN is case-insensitive.

        Conformance with URN Syntax:

                There are no additional characters reserved.

        Validation mechanism:

                None specified.

        Scope:

                Global.

3. Examples

   The following are examples of URNs that a resolver for this namespace
   can resolve:

           urn:ietf:rfc:2141
           urn:ietf:std:50
           urn:ietf:id:ietf-urn-ietf-06.txt
           urn:ietf:mtg-41-urn

4. Security Considerations

   Because this namespace defines no additional reserved characters, it
   does not add any security considerations beyond those inherent from
   the existence of the reserved characters from [1].  Further, none of
   the reserved characters from [1] are used in the definition of the
   NSS. This means that resolvers for this namespace may be considered
   "secure" in the sense that any escaping of characters in the NSS MUST
   result in the resolver indicating that the URN has incorrect syntax.

4.

5. Acknowledgments

   Thanks to various members of the URN working group for comments on
   earlier drafts of this document.  The work described in this document
   is partially supported by the National Science Foundation,
   Cooperative Agreement NCR-9218179.

4.

6. References

   Request For Comments (RFC) and Internet Draft documents are available
   from <URL:ftp://ftp.internic.net> and numerous mirror sites.

         [1]         R. Moats, "URN Syntax," RFC 2141, May 5, 1997.

         [2]         D. Crocker, P. Overell, "Augmented BNF for Syntax Specifica-
            tions:
                     Specifications: ABNF," RFC 2234, November 1997.

5.

7. Author's Address

   Ryan Moats
   AT&T
   15621 Drexel Circle
   Omaha, NE 68135-2358
   USA

   Phone:  +1 402 894-9456
   EMail:  jayhawk@att.com

Appendix A.  Example Resolution Scripts

   The following scripts are examples that can be used for resolving
   URNs in this namespace.

A.1 I2C

#!/usr/local/bin/perl

use strict;

#
# this is a URN 2 URC resolver for the ietf namespace
#

my(%cite) = (
       rfc
  bcp => "/ftp/rfc/rfc-index.txt", "/ftp/rfc/bcp-index.txt",
  fyi => "/ftp/fyi/fyi-index.txt",
       std
  id => "/ftp/std/std-index.txt",
       bcp "/ftp/internet-drafts/1id-abstracts.txt",
  rfc => "/ftp/rfc/bcp-index.txt" "/ftp/rfc/rfc-index.txt",
  std => "/ftp/std/std-index.txt"
);
my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

     (&resolve1($1,

(&resolveid($1), exit) if ($urn =~ /urn:ietf:id:(i);
(&resolverfc($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i);
     (&resolve2($1, /urn:ietf:(72)/i);
(&resolvemtg($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);
sub resolve2 resolvemtg {
  my($ietfnum, $sesnam) = @_;
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
    print "Status:  200 OK\r\n"; OK70;
    print "Content-type: text/html\r\n\r\n"; text/html70;
    print "<HTML>\n<TITLE>Citation "<HTML>0TITLE>Citation for $urn</TITLE>\n"; $urn</TITLE>0;
    print "<BODY>\n"; "<BODY>0;
    print "<H1><A HREF=\"$link\">$urn</A>:</H1>\n"; HREF=
    print "Minutes of the $sesnam working group from the " . &end($ietfnum) . " IETF";
    print "</BODY>\n</HTML>\n"; "</BODY>0/HTML>0;
    return;
  }
  my($link)="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
    print "Status:  200 OK\r\n"; OK70;
    print "Content-type: text/html\r\n\r\n"; text/html70;
    print "<HTML>\n<TITLE>Citation "<HTML>0TITLE>Citation for $urn</TITLE>\n"; $urn</TITLE>0;
    print "<BODY>\n"; "<BODY>0;
    print "<H1><A HREF=\"$link\">$urn</A>:</H1>\n"; HREF=
    print "Minutes of the $sesnam working group from the " . &end($ietfnum) . " IETF";
    print "</BODY>\n</HTML>\n"; "</BODY>0/HTML>0;
    return;
  }
  &urn_error("404 Not Found\n"); Found0);
}

sub end {
  my($inarg)=@_;
  return $inarg . "st" if ($inarg =~ /1$/);
  return $inarg . "nd" if ($inarg =~ /2$/);
  return $inarg . "rd" if ($inarg =~ /3$/);
  return $inarg . "th";
}

sub resolve1 resolverfc {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  if (!defined $cite{$scheme}) {
    &urn_error("404 Not Found\n"); Found0);
  }

  $flag = 0;
  open(INPUT, "$cite{$scheme}");
  while (<INPUT>) {
    $flag = 1 if (/^0*$value /);
    if ($flag == 1) {
      last if (/^$/);
      chop;
      push @bib,$_;
    }
  }

  if ($scheme ne "rfc") {
    print "Status:  200 OK\r\n"; OK70;
    print "Content-type: text/html\r\n\r\n"; text/html70;
    $bib[0] =~ s/^[0-9]*\s*/<B>/; s/^[0-9]*/<B>/;
    for ($i=0; $i<=$#bib; $i+=1) {
      last if ($bib[$i] =~ s/\./.<\/B>/); s/./.</B>/);
    }
    for ($i=0;$i<=$#bib;$i+=1) {
      $k=$bib[$i];
      while ($k =~ /(fyi|std|rfc|bcp)([0-9]+)(.*)/i) {
        push @ref,"$1$2";
        $k=$3;
      }
      $done="";
      foreach $j (@ref) {
        next if ($done =~ $j);
        $done .= "$j ";
        $l = $j;
        $l =~ tr/A-Z/a-z/;
        $link=&make_link("$l");
        $bib[$i] =~ s/$j/<A HREF="$link">$j<\/A>/g; HREF="$link">$j</A>/g;
      }
    }
    print "<HTML>\n<TITLE>Citation "<HTML>0TITLE>Citation for $urn</TITLE>\n"; $urn</TITLE>0;
    print "<BODY>\n"; "<BODY>0;
    $link=&make_link("$scheme$value");
    print "<H1><A HREF=\"$link\">$scheme$value</A>:</H1>\n"; HREF=
    foreach $i (@bib) {
      print "$i\n"; "$i0;
    }
    print "</BODY>\n</HTML>\n"; "</BODY>0/HTML>0;
  } else {
    print "Status:  200 OK\r\n"; OK70;
    print "Content-type: text/html\r\n\r\n"; text/html70;
    $bib[0] =~ s/^[0-9]*\s*//; s/^[0-9]*//;
    $j=0;
    for ($i=0; $i<=$#bib; $i+=1) {
      $j += ($bib[$i] =~ s/, "/, <B>"/);
      $j += ($bib[$i] =~ s/",/"<\/B>,/); s/",/"</B>,/);

    }
    for ($i=0;$i<=$#bib;$i+=1) {
      $k=$bib[$i];
      while ($k =~ /(fyi\s|std\s|rfc|bcp)([0-9]+)(.*)/i) /(fyistdrfc|bcp)([0-9]+)(.*)/i) {
        push @ref,"$1$2";
        $k=$3;
      }
      $done="";
      foreach $j (@ref) {
        next if ($done =~ $j);
        $done .= "$j ";
        $l = $j;
        $l =~ s/\s//g; s//g;
        $l =~ tr/A-Z/a-z/;
        $link=&make_link("$l");
        $bib[$i] =~ s/$j/<A HREF="$link">$j<\/A>/g; HREF="$link">$j</A>/g;
      }
    }
    print "<HTML>\n<TITLE>Citation "<HTML>0TITLE>Citation for $urn</TITLE>\n"; $urn</TITLE>0;
    print "<BODY>\n"; "<BODY>0;
    $link=&make_link("$scheme$value");
    print "<H1><A HREF=\"$link\">$scheme$value</A>:</H1>\n"; HREF=
    foreach $i (@bib) {
      print "$i\n"; "$i0;
    }
    print "</BODY>\n</HTML>\n"; "</BODY>0/HTML>0;
  }
}

sub make_link {
  my($sc);
  my($inarg)=@_;
  ($sc=$1) if ($inarg =~ /([a-z]*)/);
  return "/$sc/$inarg.ps" if (-e "/ftp/$sc/$inarg.ps");
  return "/$sc/$inarg.html" if (-e "/ftp/$sc/$inarg.html");
  return "/$sc/$inarg.txt";
}

sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status:  $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2C $code</title></head>\n"; $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URC resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
};

sub resolveid {
  my($flag,@bib,$i,$k,$j,$count,@ref);
  my($l,$link, $hdr, $done);
  my($value) = @_;
  my($scheme) = "id";

  open(INPUT, "$cite{$scheme}");
  while (<INPUT>) {
#
# capture record
#
    if ($flag == 1 || /^
      push @bib,$_;
      ($hdr = -1, $count = 0, $flag = 1) if (/^
      $count++ if (/^/);
    }
    if ($count == 1) {
      $hdr = $#bib if ($hdr == -1);
    }
    if ($count == 2) {
      for ($i=0; $i<=$hdr; $i+=1) {
            if ($bib[$i] =~ /<(.*)>/) {
              $l = $1;
              if ($l eq "draft-$value.txt" || $l eq "draft-$value.ps") {
                print "Status:  200 OK70;
                print "Content-type: text/html70;
                print "<HTML>0TITLE>Citation for $urn</TITLE>0;
                print "<BODY>0;
                print "<a href=
                print "<pre>0;
                foreach $i (@bib) {
                  print "$i";
                }
                print "</pre>0;
                print "</BODY>0/HTML>0;
                exit;
              }
            }
      }
      $flag = 0;
      @bib = ();
    }
  }
  &urn_error("404 Not Found0);

}

A.2 I2L

#!/usr/local/bin/perl

use strict;

#
# this is a URN 2 URL resolver for the ietf namespace
#

my(%pathbase) = (
  rfc => "rfc/rfc",
  fyi => "fyi/fyi",
  std => "std/std",
  bcp => "bcp/bcp",
  id => "internet-drafts/draft-",
);

my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

     (&resolve1($1,

(&resolveid($1), exit) if ($urn =~ /urn:ietf:id:(i);
(&resolverfc($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i);
     (&resolve2($1, /urn:ietf:(72)/i);
(&resolvemtg($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);

sub resolve2 resolvemtg {
  my($ietfnum, $sesnam) = @_;
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
    print "Status:  302 Moved temporarily\n"; temporarily0;
    print "Location: $link\n"; $link0;
    return;
  }
  my($link)="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
    print "Status:  302 Moved temporarily\n"; temporarily0;
    print "Location: $link\n"; $link0;
    return;
  }
  &urn_error("404 Not Found\n"); Found0);
}

sub end {
  my($inarg)=@_;
  return $inarg . "st" if ($inarg =~ /1$/);
  return $inarg . "nd" if ($inarg =~ /2$/);
  return $inarg . "rd" if ($inarg =~ /3$/);
  return $inarg . "th";
}

sub resolve1 resolverfc {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found\n")if Found0)if (!defined $pathbase{$scheme});
  my($txttry)="/ftp/$pathbase{$scheme}$value.txt";
  my($pstry)="/ftp/$pathbase{$scheme}$value.ps";
  my($htmltry)="/ftp/$pathbase{$scheme}$value.html";
MIME_SWITCH: {
    if ($accept =~ /application\/postscript/ /application/postscript/ && -f $pstry) {
      print "Status:  302 Moved temporarily\n"; temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.ps\n\n"; http://$host/$pathbase{$scheme}$value.ps0;
      last MIME_SWITCH;
    }
    if ($accept =~ /text\/html/ /text/html/ && -f $htmltry) {
      print "Status:  302 Moved temporarily\n"; temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.html\n\n"; http://$host/$pathbase{$scheme}$value.html0;
      last MIME_SWITCH;
    }
    if ($accept =~ /\*\/\*|text\/plain/ /text/plain/ && -f $txttry) {
      print "Status:  302 Moved temporarily\n"; temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.txt\n\n"; http://$host/$pathbase{$scheme}$value.txt0;
      last MIME_SWITCH;
    }
    &urn_error("404 Not Found\n"); Found0);
  }
}
sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status:  $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2L $code</title></head>\n"; $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URL resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
}

sub resolveid {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme) = "id";
  my($value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found0)if (!defined $pathbase{$scheme});
  my($txttry)="/ftp/$pathbase{$scheme}$value.txt";
  my($pstry)="/ftp/$pathbase{$scheme}$value.ps";
  my($htmltry)="/ftp/$pathbase{$scheme}$value.html";
MIME_SWITCH: {
    if ($accept =~ /application/postscript/ && -f $pstry) {
      print "Status:  302 Moved temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.ps0;
      last MIME_SWITCH;
    }
    if ($accept =~ /text/html/ && -f $htmltry) {
      print "Status:  302 Moved temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.html0;
      last MIME_SWITCH;
    }
    if ($accept =~ /text/plain/ && -f $txttry) {
      print "Status:  302 Moved temporarily0;
      print "Location: http://$host/$pathbase{$scheme}$value.txt0;
      last MIME_SWITCH;
    }
    &urn_error("404 Not Found0);
  }
}

A.3 I2Ls

#!/usr/local/bin/perl
use strict;

#
# this is a URN 2 URLs resolver for the ietf namespace
#

my(@urls);

my(%pathbase) = (
  rfc => "rfc/rfc",
  fyi => "fyi/fyi",
  std => "std/std",
  bcp => "bcp/bcp" "bcp/bcp",
             id => "internet-drafts/draft-"
);

my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

(&resolveid($1), exit) if ($urn =~ /urn:ietf:id:(i);
(&resolve1($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i); /urn:ietf:(72)/i);
(&resolve2($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);

sub resolve2 {
  my($ietfnum, $sesnam) = @_;
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
         $link=~s/^\/ftp\///;
    $link=~s/^/ftp///;
    my($ftplink)="ftp://$host/$link";
    my($httplink)="http://$host/$link";
    my($glink)="gopher://$host:70/0/$link";
    if ($accept =~ /text\/uri-list/) /text/uri-list/) { #look for text/uri-list, otherwise text/html
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
      print "#$urn\n"; "#$urn0;
      print "$ftplink\n"; "$ftplink0;
      print "$httplink\n"; "$httplink0;
      print "$glink\n"; "$glink0;
    }
    if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
      print "<head><title>URN Resolution: I2Ls</title></head>\n"; I2Ls</title></head>0;
      print "<BODY>\n"; "<BODY>0;
      print "<h1>URN $urn resolves to the following URLs:</h1>\n"; URLs:</h1>0;
      print "<hr><ul>\n"; "<hr><ul>0;
      print "<a href=\"$ftplink\">$ftplink</a>\n"; href=
      print "<a href=\"$httplink\">$httplink</a>\n"; href=
      print "<a href=\"$glink\">$glink</a>\n"; href=
      print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
    }
    return;
  }
  my($link)="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
         $link=~s/^\/ftp\///;
    $link=~s/^/ftp///;
    my($ftplink)="ftp://$host/$link";
    my($httplink)="http://$host/$link";
    my($glink)="gopher://$host:70/0/$link";
    if ($accept =~ /text\/uri-list/) /text/uri-list/) { #look for text/uri-list, otherwise text/html
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
      print "#$urn\n"; "#$urn0;
      print "$ftplink\n"; "$ftplink0;
      print "$httplink\n"; "$httplink0;
      print "$glink\n"; "$glink0;
    }
    if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
      print "<head><title>URN Resolution: I2Ls</title></head>\n"; I2Ls</title></head>0;
      print "<BODY>\n"; "<BODY>0;
      print "<h1>URN $urn resolves to the following URLs:</h1>\n"; URLs:</h1>0;
      print "<hr><ul>\n"; "<hr><ul>0;
      print "<a href=\"$ftplink\">$ftplink</a>\n"; href=
      print "<a href=\"$httplink\">$httplink</a>\n"; href=
      print "<a href=\"$glink\">$glink</a>\n"; href=
      print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
    }
    return;

  }
  &urn_error("404 Not Found\n"); Found0);
}

sub resolve1 {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found\n")if Found0)if (!defined $pathbase{$scheme});
  my($try)="/ftp/$pathbase{$scheme}$value.txt";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.txt");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.txt");
    push(@urls, "gopher://$host:70/0/$pathbase{$scheme}$value.txt");
  }
  $try="/ftp/$pathbase{$scheme}$value.ps";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.ps");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.ps");
    push(@urls, "gopher://$host:70/0/$pathbase{$scheme}$value.ps");
  }
  $try="/ftp/$pathbase{$scheme}$value.html";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.html");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.html");
  }

  &urn_error("404 Not Found\n") Found0) if ($#urls == -1);

MIME_SWITCH: {
    if ($accept =~ /text\/uri-list/) /text/uri-list/) { #look for text/uri-list, otherwise text/html
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
      print "#$urn\n"; "#$urn0;
      foreach $i (@urls) {
        print "$i\n"; "$i0;
      }
      last MIME_SWITCH;
    }
    if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
      print "<head><title>URN Resolution: I2Ls</title></head>\n"; I2Ls</title></head>0;
      print "<BODY>\n"; "<BODY>0;
      print "<h1>URN $urn resolves to the following URLs:</h1>\n"; URLs:</h1>0;
      print "<hr><ul>\n"; "<hr><ul>0;
      foreach $i (@urls) {
        print "<LI><A HREF=\"$i\">$i</A>\n"; HREF=
      }
      print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
      last MIME_SWITCH;
    }
  }
}

sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status: $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2Ls $code</title></head>\n"; I2L $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URL resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
}

sub resolveid {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($value) = @_;
  my($scheme) = "id";
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found0)if (!defined $pathbase{$scheme});
  my($try)="/ftp/$pathbase{$scheme}$value.txt";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.txt");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.txt");
    push(@urls, "gopher://$host:70/0/$pathbase{$scheme}$value.txt");
  }
  $try="/ftp/$pathbase{$scheme}$value.ps";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.ps");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.ps");
    push(@urls, "gopher://$host:70/0/$pathbase{$scheme}$value.ps");
  }
  $try="/ftp/$pathbase{$scheme}$value.html";
  if (-f $try) {
    push(@urls, "http://$host/$pathbase{$scheme}$value.html");
    push(@urls, "ftp://$host/$pathbase{$scheme}$value.html");
  }

  &urn_error("404 Not Found0) if ($#urls == -1);

MIME_SWITCH: {
    if ($accept =~ /text/uri-list/) { #look for text/uri-list, otherwise text/html
      print "Status: 200 OK0;
      print "Content-type: text/uri-list0;
      print "#$urn0;
      foreach $i (@urls) {
        print "$i0;
      }
      last MIME_SWITCH;
    }
    if ($accept =~ /text/html/) {
      print "Status: 200 OK0;
      print "Content-type: text/html0HTML>0;
      print "<head><title>URN Resolution: I2Ls</title></head>0;
      print "<BODY>0;
      print "<h1>URN $urn resolves to the following URLs:</h1>0;
      print "<hr><ul>0;
      foreach $i (@urls) {
        print "<LI><A HREF=
      }
      print "</UL>0/body>0/HTML>0;
      last MIME_SWITCH;
    }
  }
}

A.4 I2Ns

#!/usr/local/bin/perl

use strict;

#
# this is a URN 2 URNs resolver for the ietf namespace
#

my(%cite) = (
  rfc => "/ftp/rfc/rfc-index.txt",
  fyi => "/ftp/fyi/fyi-index.txt",
  std => "/ftp/std/std-index.txt",
  bcp => "/ftp/rfc/bcp-index.txt"
);

my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($port) = $ENV{'SERVER_PORT'};
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

(&resolve1("id", $1), exit) if ($urn =~ /urn:ietf:id:(/i);
(&resolve1($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i); /urn:ietf:(72)/i);
(&resolve2($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);

sub resolve2 {
  my($ietfnum, $sesnam) = @_;
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
    if ($accept =~ /text\/uri-list/) /text/uri-list/) {
        print "Status: 200 OK\n"; OK0;
        print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
        print "#$urn\n"; "#$urn0;
        return;
    }
    if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
      print "Status: 200 OK\n"; OK0;
      print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
      print "<head><title>URN Resolution: I2Ns</title></head>\n"; I2Ns</title></head>0;
      print "<BODY>\n"; "<BODY>0;
      print "<h1>URN $urn resolves to the following URNs:</h1>\n"; URNs:</h1>0;
      print "<hr><ul>\n"; "<hr><ul>0;
      print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
      return;
    }
  }
  my($link)="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
    if ($accept =~ /text\/uri-list/) /text/uri-list/) {
        print "Status: 200 OK\n"; OK0;
        print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
        print "#$urn\n"; "#$urn0;
        return;
    }
    if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
        print "Status: 200 OK\n"; OK0;
        print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
        print "<head><title>URN Resolution: I2Ns</title></head>\n"; I2Ns</title></head>0;
        print "<BODY>\n"; "<BODY>0;
        print "<h1>URN $urn resolves to the following URNs:</h1>\n"; URNs:</h1>0;
        print "<hr><ul>\n"; "<hr><ul>0;
        print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
        return;
    }
  }
  &urn_error("404 Not Found\n"); Found0);
}

sub end {
  my($inarg)=@_;
  return $inarg . "st" if ($inarg =~ /1$/);
  return $inarg . "nd" if ($inarg =~ /2$/);
  return $inarg . "rd" if ($inarg =~ /3$/);
  return $inarg . "th";
}

sub resolve1 {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  if (!defined $cite{$scheme}) {
    &urn_error("404 Not Found\n"); Found0);
  }

  $flag = 0;
  open(INPUT, "$cite{$scheme}");
  while (<INPUT>) {
    $flag = 1 if (/^0*$value /);
    if ($flag == 1) {
      last if (/^$/);
      chop;
      push @bib,$_;
    }
  }

  $k=join " ",@bib;
  while ($k =~ /(\S*)\s*(fyi|std|rfc|bcp)\s*([0-9]+)(.*)/i) /(fyi|std|rfc|bcp)([0-9]+)(.*)/i) {
    $k=$4;
    $a=$2; $b=$3;
    if (($a ne $scheme || $b ne $value) && ($1 !~ /obso/i)){
      $a =~ tr/A-Z/a-z/;
      $b =~ s/^0*//;
      push @ref,"urn:ietf:$a:$b";
    }
  }

MIME_SWITCH: {
    if ($accept =~ /text\/uri-list/) /text/uri-list/) {
        print "Status: 200 OK\n"; OK0;
        print "Content-type: text/uri-list\n\n\n"; text/uri-list0;
        print "#$urn\n"; "#$urn0;
        foreach $i (@ref) {
            print "$i\n"; "$i0;
        }
        last MIME_SWITCH;
    }
  if ($accept =~ /\*\/\*|text\/html/) /text/html/) {
    print "Status: 200 OK\n"; OK0;
    print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
    print "<head><title>URN Resolution: I2Ns</title></head>\n"; I2Ns</title></head>0;
    print "<BODY>\n"; "<BODY>0;
    print "<h1>URN $urn resolves to the following URNs:</h1>\n"; URNs:</h1>0;
    print "<hr><ul>\n"; "<hr><ul>0;
        foreach $i (@ref) {
            print "<li>$i: Click to resolve using\n"; using0;
            print "<a href=\"http://$host:$port/uri-res/I2C?$i\">I2C</a>,\n"; href=
            print "<a href=\"http://$host:$port/uri-res/I2L?$i\">I2L</a>,\n"; href=
            print "<a href=\"http://$host:$port/uri-res/I2Ls?$i\">I2Ls</a>,\n"; href=
            print "<a href=\"http://$host:$port/uri-res/I2R?$i\">I2R</a>,\n"; href=
            print "<a href=\"http://$host:$port/uri-res/I2Rs?$i\">I2Rs</a>\n"; href=
        }
    print "</UL>\n</body>\n</HTML>\n"; "</UL>0/body>0/HTML>0;
  }
}
}

sub make_link {
  my($sc);
  my($inarg)=@_;
  ($sc=$1) if ($inarg =~ /([a-z]*)/);
  return "/$sc/$inarg.ps" if (-e "/ftp/$sc/$inarg.ps");
  return "/$sc/$inarg.html" if (-e "/ftp/$sc/$inarg.html");
  return "/$sc/$inarg.txt";
}

sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status: $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2Ns $code</title></head>\n"; $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URC URN resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
};

A.5 I2R

#!/usr/local/bin/perl

use strict;

#
# this is a URN 2 resource resolver for the ietf namespace
#

my(%pathbase) = (
  rfc => "rfc/rfc",
  fyi => "fyi/fyi",
  std => "std/std",
  bcp => "bcp/bcp" "bcp/bcp",
  id => "internet-drafts/draft-"
);

my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

print "$urn0;
(&resolveid($1), exit) if ($urn =~ /urn:ietf:id:(i);
(&resolve1($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i); /urn:ietf:(72)/i);
(&resolve2($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);

sub resolve2 {
  my($ietfnum, $sesnam) = @_;
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
      print "Status:  200 OK\n"; OK0;
      print "Content-type: text/plain\n\n"; text/plain0;
      open(FILE, "$link");
      while (<FILE>) {
          print $_;
      }
      close FILE;
    return;
  }
  my($link)="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
      print "Status:  200 OK\n"; OK0;
      print "Content-type: text/plain\n\n"; text/plain0;
      open(FILE, "$link");
      while (<FILE>) {
          print $_;
      }
      close FILE;
    return;
  }
  &urn_error("404 Not Found\n"); Found0);
}

sub end {
  my($inarg)=@_;
  return $inarg . "st" if ($inarg =~ /1$/);
  return $inarg . "nd" if ($inarg =~ /2$/);
  return $inarg . "rd" if ($inarg =~ /3$/);
  return $inarg . "th";
}

sub resolve1 {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found\n")if Found0)if (!defined $pathbase{$scheme});
  my($txttry)="/ftp/$pathbase{$scheme}$value.txt";
  my($pstry)="/ftp/$pathbase{$scheme}$value.ps";
  my($htmltry)="/ftp/$pathbase{$scheme}$value.html";
MIME_SWITCH: {
    if ($accept =~ /application/postscript/ && -f $pstry) {
      print "Status:  200 OK0;
      print "Content-type: application/postscript0;
      open(FILE, "$pstry");
      while (<FILE>) {
          print $_;
      }
      close FILE;
      last MIME_SWITCH;
    }
    if ($accept =~ /text/html/ && -f $htmltry) {
        print "Status:  200 OK0;
        print "Content-type: text/html0;
        open(FILE, "$htmltry");
        while (<FILE>) {
            print $_;
        }
        close FILE;
        last MIME_SWITCH;
    }
    if ($accept =~ /text/plain/ && -f $txttry) {
        print "Status:  200 OK0;
        print "Content-type: text/plain0;
        open(FILE, "$txttry");
        while (<FILE>) {
            print $_;
        }
        close FILE;
        last MIME_SWITCH;
    }
    &urn_error("404 Not Found0);
  }
}

sub resolveid {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link);
  my($scheme) = "id";
  my($value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found0)if (!defined $pathbase{$scheme});
  my($txttry)="/ftp/$pathbase{$scheme}$value.txt";
  my($pstry)="/ftp/$pathbase{$scheme}$value.ps";
  my($htmltry)="/ftp/$pathbase{$scheme}$value.html";
MIME_SWITCH: {
    if ($accept =~ /application\/postscript/ /application/postscript/ && -f $pstry) {
      print "Status:  200 OK\n"; OK0;
      print "Content-type: application/postscript\n\n"; application/postscript0;
      open(FILE, "$pstry");
      while (<FILE>) {
          print $_;
      }
      close FILE;
      last MIME_SWITCH;
    }
    if ($accept =~ /text\/html/ /text/html/ && -f $htmltry) {
        print "Status:  200 OK\n"; OK0;
        print "Content-type: text/html\n\n"; text/html0;
        open(FILE, "$htmltry");
        while (<FILE>) {
            print $_;
        }
        close FILE;
        last MIME_SWITCH;
    }
    if ($accept =~ /\*\/\*|text\/plain/ /text/plain/ && -f $txttry) {
        print "Status:  200 OK\n"; OK0;
        print "Content-type: text/plain\n\n"; text/plain0;
        open(FILE, "$txttry");
        while (<FILE>) {
            print $_;
        }
        close FILE;
        last MIME_SWITCH;
    }
    &urn_error("404 Not Found\n"); Found0);
  }
}

sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status:  $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2R $code</title></head>\n"; $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URL resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
}
A.6 I2Rs

#!/usr/local/bin/perl

use strict;

#
# this is a URN 2 resources resolver for the ietf namespace
#

my(@urls);

my(%pathbase) = (
  rfc => "rfc/rfc",
  fyi => "fyi/fyi",
  std => "std/std",
  bcp => "bcp/bcp" "bcp/bcp",
  id => "internet-drafts/draft-"
);

my(%number2date) = (
  41 => "98apr",
  40 => "97dec", 39 => "97aug", 38 => "97apr",
  37 => "96dec", 36 => "96jun", 35 => "96mar",
  34 => "95dec", 33 => "95jul", 32 => "95apr",
  31 => "94dec", 30 => "94jul", 29 => "94mar",
  28 => "93nov", 27 => "93jul", 26 => "93mar",
  25 => "92nov", 24 => "92jul", 23 => "92mar",
  22 => "91nov", 21 => "91jul", 20 => "91mar",
  19 => "90dec" );

my($wgpath) = "/ftp/ietf";
my($urn) = $ENV{'QUERY_STRING'};
my($host) = $ENV{'SERVER_NAME'}; #get my host name for ftp: URLs
my($accept) = $ENV{'HTTP_ACCEPT'}; #this is the "Accept:" HTTP header

(&resolveid($1), exit) if ($urn =~ /urn:ietf:id:()/i);
(&resolve1($1, $2), exit) if ($urn =~ /urn:ietf:(\w*):(\d*)/i); /urn:ietf:(72)/i);
(&resolve2($1, $2), exit) if ($urn =~ /urn:ietf:mtg-(\d*)-(\w*)/i);
     &urn_error("400 /urn:ietf:mtg-(9*)-(
120&urn_error("400 Bad Request\n"); Request0);

sub resolve2 {
  my($ietfnum, $sesnam) = @_;
  my(@vers,$i);
  &urn_error("404 Not Found\n") Found0) if (!defined $number2date{$ietfnum});
  my($date)=$number2date{$ietfnum};
  my($link)="$wgpath/$sesnam/$sesnam-minutes-$date.txt";
  if (-f $link) {
      push(@vers,$link);
  }
  $link="$wgpath/$date/$sesnam-minutes-$date.txt";
  if (-f $link) {
      push(@vers,$link);
  }
  &urn_error("404 Not Found\n") Found0) if ($#vers==-1);

  print "Status: 200 OK\n"; OK0;
  print "Content-type: multipart/alternative; boundary=endpart\n\n"; boundary=endpart0;
  foreach $i (@vers) {
      print "--endpart\n"; "--endpart0;
      if ($i =~ /html$/) {
          print "Content-Type: text/html\n\n"; text/html0;
      }
      if ($i =~ /txt$/) {
          print "Content-Type: text/plain\n\n"; text/plain0;
      }
      if ($i =~ /ps$/) {
          print "Content-Type: application/postscript\n\n"; application/postscript0;
      }
      open(FILE, "$i");
      while (<FILE>) {
          print "$_";
      }
      close FILE;
  }
  print "--endpart\n"; "--endpart0;
}

sub resolve1 {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link,@vers);
  my($scheme, $value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found\n")if Found0)if (!defined $pathbase{$scheme});
  my($try)="/ftp/$pathbase{$scheme}$value.txt";
  if (-f $try) {
      push(@vers, $try);
  }
  $try="/ftp/$pathbase{$scheme}$value.ps";
  if (-f $try) {
      push(@vers, $try);
  }
  $try="/ftp/$pathbase{$scheme}$value.html";
  if (-f $try) {
      push(@vers, $try);
  }
  print "Status: 200 OK0;
  print "Content-type: multipart/alternative; boundary=endpart0;
  foreach $i (@vers) {
      print "--endpart0;
      if ($i =~ /html$/) {
          print "Content-Type: text/html0;
      }
      if ($i =~ /txt$/) {
          print "Content-Type: text/plain0;
      }
      if ($i =~ /ps$/) {
          print "Content-Type: application/postscript0;
      }
      open(FILE, "$i");
      while (<FILE>) {
          print "$_";
      }
      close FILE;
  }
  print "--endpart0;
}

sub resolveid {
  my($flag,@bib,$i,$k,$j,$done,@ref);
  my($l,$link,@vers);
  my($scheme) = "id";
  my($value) = @_;
  $scheme =~ tr/A-Z/a-z/;
  &urn_error("404 Not Found0)if (!defined $pathbase{$scheme});
  my($try)="/ftp/$pathbase{$scheme}$value.txt";
  if (-f $try) {
      push(@vers, $try);
  }
  $try="/ftp/$pathbase{$scheme}$value.ps";
  if (-f $try) {
      push(@vers, $try);
  }
  $try="/ftp/$pathbase{$scheme}$value.html";
  if (-f $try) {
      push(@vers, $try);
  }
  print "Status: 200 OK\n"; OK0;
  print "Content-type: multipart/alternative; boundary=endpart\n\n"; boundary=endpart0;
  foreach $i (@vers) {
      print "--endpart\n"; "--endpart0;
      if ($i =~ /html$/) {
          print "Content-Type: text/html\n\n"; text/html0;
      }
      if ($i =~ /txt$/) {
          print "Content-Type: text/plain\n\n"; text/plain0;
      }
      if ($i =~ /ps$/) {
          print "Content-Type: application/postscript\n\n"; application/postscript0;
      }
      open(FILE, "$i");
      while (<FILE>) {
          print "$_";
      }
      close FILE;
  }
  print "--endpart\n"; "--endpart0;
}
sub urn_error {
  my($code) = @_; #store failure code here...

  print "Status: $code";
  print "Content-type: text/html\n\n<HTML>\n"; text/html0HTML>0;
  print "<head><title>URN Resolution: I2Rs $code</title></head>\n"; $code</title></head>0;
  print "<BODY>\n"; "<BODY>0;
  print "<h1>URN to URL resolution failed for the URN:</h1>\n"; URN:</h1>0;
  print "<hr><h3>$urn</h3>\n"; "<hr><h3>$urn</h3>0;
  print "</body>\n"; "</body>0;
  print "</html>\n"; "</html>0;
  exit;
}