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Re: RFC 2141 on URN Syntax

From: Arun Manchanda <nalua@hotmail.com>
Date: Thu, 12 Jun 1997 07:14:05 PDT
Message-Id: <199706121414.HAA18772@f40.hotmail.com>
To: nalua@rocketmail.com
Cc: w3c-dist-auth@w3.org, urn-ietf@bunyip.com


>From w3c-dist-auth-request@w3.org Fri May  9 09:27:02 1997
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>Date: Fri, 09 May 1997 10:08:42 -0600
>To: Sukanta Ganguly <SGANGULY@novell.com>
>From: "Ron Daniel, Jr." <rdaniel@lanl.gov>
>Subject: Re: RFC 2141 on URN Syntax
>Cc: w3c-dist-auth@w3.org, urn-ietf@bunyip.com
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>At 08:54 AM 5/9/97 -0600, Sukanta Ganguly wrote:
>>Hi,
>>  I wanted to mention some things about the rfc 2141 that I found 
confusing.
>
>You should bring these questions up on the URN-WG list, not the
>Web DAV list. The URN list is urn-ietf@bunyip.com. I have added it
>to the CC list on this reply.
>
>>The syntax for a URN is specified as
>><URN> ::= "urn:" <NID> ":" <NSS>
>>and NSS also has ":" as a characters recognized within the <others> 
rule.
>>Based on this
>>    URN:foo::      -> Is this a valid URN ??
>
>That will depend on the rules for the namespace foo. The URN syntax
>is an attempt to be as liberal as possible so as to allow many
>different namespaces to exist. The rules for particular namespaces
>are intended to be much stricter. As an example, take a look at
>the URN-WG's internet draft on using bibliographic identifiers as URNs.
>Two of the namespaces in that document (ISBN and ISSN) disallow the use
>of ':' and many other characters. The third (SICI) has much more
>liberal rules because SICIs use lots of funny characters.
>
>>I feel that is ":" is used as a reserved terminator of a subsection of 
a
>>rule then it should not be used in the recognized character sets for 
the
>>other sub-sections of the rule. So I would imagine that ":" is not 
present
>>as a recognizable character within the <other> rule of NSS subsection.
>
>The URN sytnax RFC takes a strong position on the first two occurances
>of ':'. After that, it is up to particular namespaces how ':' is or is 
not
>used.
>
>>It just adds an extra amount of parsing effort for the applications to 
have
>>this feature in their parsing mechanisms. I don't say that it is 
impossible
>>to have it, but as a application developer, it  would be a much messy
>>approach for me to write code that has this feature in it. I hope this 
not
>>taken as a negative criticism. 
>
>No, it is not taken as a negative criticism. However, one of the 
requirements
>on URNs was the ability to grandfather legacy naming systems (such as 
SICIs).
>If allowing ':' makes it easier to accomodate some naming schemes, then 
we
>thought it would be worth some additional implementation difficulty. 
The
>additional difficulty seems very small. The first two ':' characters 
are
>required, so once one has stripped off the "urn:" prefix and the NID
>field with its colon, no more special treatment of ':' is required for
>a general URN parser. You will probably want to use the NID to lookup
>special parsing rules for the namespace, but that is another story.
>
>
>>I have a similar concern regarding the usage of "%" character within 
the
>><NSS> subsection. This is what the rule resolution says 
>><NSS> ::= 1*<URN chars>
>><URN chars> ::= <trans> | "%" <hex> <hex>
>><trans> ::= <upper> | <lower> | <number> | <other> | <reserved>
>><reserved> ::= '%" | "/" | "?" | "#"
>>
>>Here we observe that 
>>
>>  <NSS> ::= %    could be a valid rule according to the  rule 
definition. At
>>the same time the system has another defination that says wheneever 
"%" is
>>used two  <hex> characters should be used.
>>
>>  <NSS> ::=%%12  -> could also be a valid syntax for NSS.  
>>
>>My suggestion here is to remove "%" from the <reserved> subsection of 
<NSS>
>>rules.
>>
>>Please let me know if my thinking is along the lines of what the group 
has
>>in mind or am I way out of wack.
>
>Single occurances of '%' are disallowed. '%' is supposed to ALWAYS mean
>that the next two characters will be hex digits that are taken to
>form an octet.
>
>
>>I appreciate your acceptance of my
>>participation in the group.
>>
>>Thank You
>>Sukanta Ganguly
>>
>>>>> Jim Whitehead <ejw@ics.uci.edu> 05/06/97 12:07PM >>>
>>
>>Of potential interest to participants of this WG.
>>
>>- Jim
>>
>>>To: IETF-Announce: ;
>>>Subject: RFC 2141 on URN Syntax
>>>Cc: rfc-ed@isi.edu 
>>>Mime-Version: 1.0
>>>Date: Mon, 05 May 97 13:53:28 PDT
>>>Sender:ietf-announce-request@ietf.org 
>>>From: RFC Editor <rfc-ed@isi.edu>
>>>
>>>
>>>A new Request for Comments is now available in online RFC libraries.
>>>
>>>
>>>        RFC 2141:
>>>
>>>        Title:      URN Syntax
>>>        Author:     R. Moats
>>>        Date:       May 1997
>>>        Mailbox:    jayhawk@ds.internic.net 
>>>        Pages:      8
>>>        Characters: 14077
>>>        Updates/Obsoletes: None
>>>
>>>        URL:        ftp://ds.internic.net/rfc/rfc2141.txt 
>>>
>>>
>>>Uniform Resource Names (URNs) are intended to serve as persistent,
>>>location-independent, resource identifiers. This document sets
>>>forward the canonical syntax for URNs.  A discussion of both existing
>>>legacy and new namespaces and requirements for URN presentation and
>>>transmission are presented.  Finally, there is a discussion of URN
>>>equivalence and how to determine it. This document is the product of
>>>the Uniform Resource Names Working Group of the IETF.
>>>
>>>This is now a Proposed Standard Protocol.
>>>
>>>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.
>>>
>>>This announcement is sent to the IETF list and the RFC-DIST list.
>>>Requests to be added to or deleted from the IETF distribution list
>>>should be sent to IETF-REQUEST@CNRI.RESTON.VA.US.  Requests to be
>>>added to or deleted from the RFC-DIST distribution list should
>>>be sent to RFC-DIST-REQUEST@ISI.EDU.
>>>
>>>Details on obtaining RFCs via FTP or EMAIL may be obtained by sending
>>>an EMAIL message to rfc-info@ISI.EDU with the message body
>>>help: ways_to_get_rfcs.  For example:
>>>
>>>        To: rfc-info@ISI.EDU 
>>>        Subject: getting rfcs
>>>
>>>        help: ways_to_get_rfcs
>>>
>>>Requests for special distribution should be addressed to either the
>>>author of the RFC in question, or to admin@DS.INTERNIC.NET.  Unless
>>>specifically noted otherwise on the RFC itself, all RFCs are for
>>>unlimited distribution.
>>>
>>>Submissions for Requests for Comments should be sent to
>>>RFC-EDITOR@ISI.EDU.  Please consult RFC 1543, Instructions to RFC
>>>Authors, for further information.
>>>
>>>
>>>Joyce K. Reynolds and Mary Kennedy
>>>USC/Information Sciences Institute
>>>
>>
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>Ron Daniel Jr.              voice:+1 505 665 0597
>Advanced Computing Lab        fax:+1 505 665 4939
>MS B287                     email:rdaniel@lanl.gov
>Los Alamos National Lab      http://www.acl.lanl.gov/~rdaniel
>Los Alamos, NM, USA, 87545  
>
>



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Received on Thursday, 12 June 1997 10:15:05 GMT

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