Subject: [MIB-DOCTORS] FW: [Ltru] Re: Language Tag MIB Textual Convention

From: "Romascanu, Dan \(Dan\)" <[email-masked]>
Date: Thu, 9 Nov 2006 20:59:09 +0200

-----Original Message-----
From: David McWalter [mailto:[email-masked]] 
Sent: Thursday, November 09, 2006 7:52 AM
To: Randy Presuhn; Bill Fenner; [email-masked]; Romascanu, Dan
(Dan)
Cc: LTRU Working Group; [email-masked]
Subject: RE: [Ltru] Re: Language Tag MIB Textual Convention

Thanks, Randy.

You're especially correct about the need for uniquely-determined case
values for indexes.  I've taken a guess that this is the right thing to
do for URI/URLs as well.

Revised text...
DMcW.

LANGTAG-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, mib-2             FROM SNMPv2-SMI
    TEXTUAL-CONVENTION                 FROM SNMPv2-TC;

langTagMIB MODULE-IDENTITY
    LAST-UPDATED "200611080000Z" -- 8 November 2006
    ORGANIZATION "IETF Operations and Management Area"
    CONTACT-INFO "EMail: [email-masked]"
    DESCRIPTION
            "The MIB module defines textual conventions for representing
            generic tags."
    REVISION     "200611080000Z" -- 8 November 2006
    DESCRIPTION
           "Initial revision, published as RFC yyyy."
    -- RFC Ed.: replace yyyy with actual RFC number & remove this note
    ::= { mib-2 yyyy }
    -- RFC Ed.: replace yyyy with actual RFC number & remove this note

LanguageTag ::= TEXTUAL-CONVENTION
   DISPLAY-HINT "100a"
   STATUS      current
   DESCRIPTION
            "A language tag, constructed in accordance with BCP 47.

            Only lowercase characters are allowed.  The purpose of this
            restriction is to provide unique language tags for use as
            indexes.  BCP 47 recommends case conventions for user
            interfaces, but objects using this convention MUST use
            only lowercase.

            In theory, BCP 47 language tags are of unlimited length.
            This language tag is of limited length.  The analysis of
            language tag lengths in BCP 47 confirms that this limit
            will not pose a problem in practice."
   REFERENCE "RFC 4646 BCP 47"
   SYNTAX      OCTET STRING (SIZE (1..100))

Uri ::= TEXTUAL-CONVENTION
   DISPLAY-HINT "1024a"
   STATUS      current
   DESCRIPTION
            "A Uniform Resource Identifier (URI) as defined by STD 66.

            Only lowercase characters are allowed.  The purpose of this
            restriction is to provide unique URIs for use as indexes.
            URI normalization capitalizes letters in escape sequences,
            but objects using this convention MUST use only lowercase.

            STD 66 URIs are of unlimited length.  This textual
            convention imposes a length limit on the URIs that it can
            represent."
   REFERENCE "RFC 3986 STD 66 and RFC 3305"
   SYNTAX      OCTET STRING (SIZE (1..1024))

Url ::= TEXTUAL-CONVENTION
   DISPLAY-HINT "1024a"
   STATUS      current
   DESCRIPTION
            "A Uniform Resource Locator (URL) as defined by STD 66.

            Only lowercase characters are allowed.  The purpose of this
            restriction is to provide unique URLs for use as indexes.
            URL normalization capitalizes letters in escape sequences,
            but objects using this convention MUST use only lowercase.

            STD 66 URLs are of unlimited length.  This textual
            convention imposes a length limit on the URLs that it can
            represent."
   REFERENCE "RFC 3986 STD 66 and RFC 3305"
   SYNTAX      OCTET STRING (SIZE (1..1024))

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---

From: Juergen Schoenwaelder <[email-masked]>
Date: Thu, 9 Nov 2006 20:36:37 +0100

>    SYNTAX      OCTET STRING (SIZE (1..1024))

I have problems with these definitions:

a) I dislike the arbitrary length restriction. If needed, define TCs such
   as Uri, Uri1024, Uri255 and so on so that MIB module writers can choose
   how constrained they want to be. Unfortunately, the SMIv2 does not
   allow to "subtype" TCs, so this requires text duplication.

b) I think the requirements for lowercase characters is broken. We should
   simply require normalized URIs as defined in section 6 of RFC 3986.
   (Note that only parts of a URI are actually case-insensitive and that
   there are other sources of variations for the same URI.)

c) I fail to see why we have a definition for a URI and a URL. RFC 3986
   says in section 1.1.3:

     [...] Future specifications and related documentation should
     use the general term "URI" rather than the more restrictive terms
     "URL" and "URN" [RFC3305].

   There is more text in the RFC which explains that the distinction of
   different classes of URIs is not very useful.

/js

-- 
Juergen Schoenwaelder		 International University Bremen
				 (Jacobs University Bremen as of Spring 2007)
<http://www.eecs.iu-bremen.de/>	 P.O. Box 750 561, 28725 Bremen, Germany