URI MIB: MIB Textual Conventions for Uniform Resource Identifiers (URIs)
Three shared MIB data types for writing URIs, so every MIB module does not invent its own.
McWalter, D., Ed., "MIB Textual Conventions for Uniform Resource Identifiers (URIs)", RFC 5017, DOI 10.17487/RFC5017, September 2007, <https://www.rfc-editor.org/info/rfc5017>.
@misc{rfc5017,
series = {Request for Comments},
number = 5017,
howpublished = {RFC 5017},
publisher = {RFC Editor},
doi = {10.17487/RFC5017},
url = {https://www.rfc-editor.org/info/rfc5017},
author = {D. McWalter},
title = {{MIB Textual Conventions for Uniform Resource Identifiers (URIs)}},
pagetotal = 7,
year = 2007,
month = sep,
} RFC text
Contents
Network Working Group D. McWalter, Ed.
Request for Comments: 5017 Data Connection Ltd
Category: Standards Track September 2007
MIB Textual Conventions for Uniform Resource Identifiers (URIs)
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.
Abstract
This MIB module defines textual conventions to represent STD 66
Uniform Resource Identifiers (URIs). The intent is that these
textual conventions will be imported and used in MIB modules that
would otherwise define their own representation(s).
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. The Internet-Standard Management Framework . . . . . . . . . . 2
4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 6
1. Introduction
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
It defines textual conventions to represent STD 66 [RFC3986] URIs,
which are further described by [RFC3305].
Three textual conventions are defined: one of unrestricted length,
and two of different restricted lengths. Which length is appropriate
will depend on tradeoffs made in particular MIB modules. The purpose
of providing standard restricted-length textual conventions is to
improve compatibility between MIB modules that require restricted-
length URIs.
If a URI needs to be used as an index object, then the 'Uri' TEXTUAL-
CONVENTION SHOULD be subtyped to a length appropriate for the Object
Identifier (OID) of which it is part. The description of the 'Uri'
TEXTUAL-CONVENTION discusses this case.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
[RFC2580].
4. Definitions
URI-TC-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, mib-2 FROM SNMPv2-SMI -- [RFC2578]
TEXTUAL-CONVENTION FROM SNMPv2-TC; -- [RFC2579]
uriTcMIB MODULE-IDENTITY
LAST-UPDATED "200709100000Z" -- 10 September 2007
ORGANIZATION "IETF Operations and Management (OPS) Area"
CONTACT-INFO "EMail: ops-area@ietf.org
Home page: http://www.ops.ietf.org/"
DESCRIPTION
"This MIB module defines textual conventions for
representing URIs, as defined by RFC 3986 STD 66."
REVISION "200709100000Z" -- 10 September 2007
DESCRIPTION
"Initial revision, published as RFC 5017.
Copyright (C) The IETF Trust (2007). This version of this
MIB module is part of RFC 5017; see the RFC itself for full
legal notices."
::= { mib-2 164 }
Uri ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1a"
STATUS current
DESCRIPTION
"A Uniform Resource Identifier (URI) as defined by STD 66.
Objects using this TEXTUAL-CONVENTION MUST be in US-ASCII
encoding, and MUST be normalized as described by RFC 3986
Sections 6.2.1, 6.2.2.1, and 6.2.2.2. All unnecessary
percent-encoding is removed, and all case-insensitive
characters are set to lowercase except for hexadecimal
digits, which are normalized to uppercase as described in
Section 6.2.2.1.
The purpose of this normalization is to help provide unique
URIs. Note that this normalization is not sufficient to
provide uniqueness. Two URIs that are textually distinct
after this normalization may still be equivalent.
Objects using this TEXTUAL-CONVENTION MAY restrict the
schemes that they permit. For example, 'data:' and 'urn:'
schemes might not be appropriate.
A zero-length URI is not a valid URI. This can be used to
express 'URI absent' where required, for example when used
as an index field.
Where this TEXTUAL-CONVENTION is used for an index field,
it MUST be subtyped to restrict its length. There is an
absolute limit of 128 subids for an OID, and it is not
efficient to have OIDs whose length approaches this
limit."
REFERENCE "RFC 3986 STD 66 and RFC 3305"
SYNTAX OCTET STRING
Uri255 ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255a"
STATUS current
DESCRIPTION
"A Uniform Resource Identifier (URI) as defined by STD 66.
Objects using this TEXTUAL-CONVENTION MUST be in US-ASCII
encoding, and MUST be normalized as described by RFC 3986
Sections 6.2.1, 6.2.2.1, and 6.2.2.2. All unnecessary
percent-encoding is removed, and all case-insensitive
characters are set to lowercase except for hexadecimal
digits, which are normalized to uppercase as described in
Section 6.2.2.1.
The purpose of this normalization is to help provide unique
URIs. Note that this normalization is not sufficient to
provide uniqueness. Two URIs that are textually distinct
after this normalization may still be equivalent.
Objects using this TEXTUAL-CONVENTION MAY restrict the
schemes that they permit. For example, 'data:' and 'urn:'
schemes might not be appropriate.
A zero-length URI is not a valid URI. This can be used to
express 'URI absent' where required, for example when used
as an index field.
STD 66 URIs are of unlimited length. Objects using this
TEXTUAL-CONVENTION impose a length limit on the URIs that
they can represent. Where no length restriction is
required, objects SHOULD use the 'Uri' TEXTUAL-CONVENTION
instead. Objects used as indices SHOULD subtype the 'Uri'
TEXTUAL-CONVENTION."
REFERENCE "RFC 3986 STD 66 and RFC 3305"
SYNTAX OCTET STRING (SIZE (0..255))
Uri1024 ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1024a"
STATUS current
DESCRIPTION
"A Uniform Resource Identifier (URI) as defined by STD 66.
Objects using this TEXTUAL-CONVENTION MUST be in US-ASCII
encoding, and MUST be normalized as described by RFC 3986
Sections 6.2.1, 6.2.2.1, and 6.2.2.2. All unnecessary
percent-encoding is removed, and all case-insensitive
characters are set to lowercase except for hexadecimal
digits, which are normalized to uppercase as described in
Section 6.2.2.1.
The purpose of this normalization is to help provide unique
URIs. Note that this normalization is not sufficient to
provide uniqueness. Two URIs that are textually distinct
after this normalization may still be equivalent.
Objects using this TEXTUAL-CONVENTION MAY restrict the
schemes that they permit. For example, 'data:' and 'urn:'
schemes might not be appropriate.
A zero-length URI is not a valid URI. This can be used to
express 'URI absent' where required, for example when used
as an index field.
STD 66 URIs are of unlimited length. Objects using this
TEXTUAL-CONVENTION impose a length limit on the URIs that
they can represent. Where no length restriction is
required, objects SHOULD use the 'Uri' TEXTUAL-CONVENTION
instead. Objects used as indices SHOULD subtype the 'Uri'
TEXTUAL-CONVENTION."
REFERENCE "RFC 3986 STD 66 and RFC 3305"
SYNTAX OCTET STRING (SIZE (0..1024))
END
5. Security Considerations
See also the Security Considerations of STD 66 [RFC3986].
This MIB module does not define any management objects. Instead, it
defines a textual convention that may be imported by other MIB
modules and used for object definitions.
Meaningful security considerations can only be written in the MIB
modules that define management objects. This document therefore has
no impact on the security of the Internet.
6. IANA Considerations
URI-TC-MIB is rooted under the mib-2 subtree. IANA has assigned {
mib-2 164 } to the URI-TC-MIB module specified in this document.
7. Acknowledgements
This module was generated by editing together contributions from
Randy Presuhn, Dan Romascanu, Bill Fenner, Juergen Schoenwaelder, and
others.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Textual Conventions for SMIv2",
STD 58, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Conformance Statements for SMIv2", STD 58, RFC 2580,
April 1999.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
8.2. Informative References
[RFC3305] Mealling, M. and R. Denenberg, "Report from the Joint W3C/
IETF URI Planning Interest Group: Uniform Resource
Identifiers (URIs), URLs, and Uniform Resource Names
(URNs): Clarifications and Recommendations", RFC 3305,
August 2002.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for
Internet-Standard Management Framework", RFC 3410,
December 2002.
Author's Address
David McWalter (editor)
Data Connection Ltd
100 Church Street
Enfield EN2 6BQ
United Kingdom
EMail: dmcw@dataconnection.com
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
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OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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AI ELI5
On this page
§1Introduction and Purpose
This memo defines part of the Management Information Base (MIB) used with network management protocols. It defines textual conventions for representing URIs as defined in STD 66 (RFC 3986), which are further described by RFC 3305.
Three conventions are defined: one of unlimited length and two of different restricted lengths. Which length fits depends on tradeoffs in the particular MIB module. Providing standard restricted-length conventions is meant to improve compatibility between MIB modules that need restricted-length URIs.
The intent, from the abstract, is that these conventions will be imported by MIB modules that would otherwise define their own representations.
Instead of everyone drawing their own box for a web address, there is now a standard box in three sizes that everybody can copy.
§3The Management Framework Behind It
The RFC fits into the Internet-Standard Management Framework, which RFC 3410 describes. Managed objects are held in a virtual information store called the MIB, and are generally accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined with the Structure of Management Information (SMI). This module is compliant with SMIv2, described in STD 58 (RFC 2578, RFC 2579 and RFC 2580).
Network devices keep a big list of facts about themselves. This document adds one more kind of entry to that list's rulebook.
§4The Three Textual Conventions
The module URI-TC-MIB is rooted at { mib-2 164 }. It defines three conventions, all built on OCTET STRING.
Uri: no length restriction, display hint1a.Uri255: size 0 to 255, display hint255a.Uri1024: size 0 to 1024, display hint1024a.
All three share the same rules for content, described in the next section. Their descriptions note that STD 66 URIs are of unlimited length, so objects using the restricted forms impose a limit on what they can represent. Where no limit is needed, objects SHOULD use Uri.
There are three boxes: a stretchy one, a medium one and a larger one. Pick the stretchy one unless you really need a size limit.
| Convention | Size | Display hint |
|---|---|---|
| Uri | Unrestricted | 1a |
| Uri255 | 0 to 255 | 255a |
| Uri1024 | 0 to 1024 | 1024a |
§5Rules for URI Values
Objects using these conventions MUST use US-ASCII encoding and MUST be normalized as described in Sections 6.2.1, 6.2.2.1 and 6.2.2.2 of RFC 3986. Unnecessary percent-encoding is removed, and case-insensitive characters are set to lowercase, except hexadecimal digits, which are normalized to uppercase.
The purpose is to help provide unique URIs, but the RFC says the normalization is not sufficient: two URIs that differ textually after normalization may still be equivalent.
Objects MAY restrict the schemes they permit; the text notes that data: and urn: might not be appropriate. A zero-length URI is not a valid URI, which can be used to express 'URI absent', for example in an index field.
Everyone must write the address the same tidy way, with the same capital and small letters, so two copies of the same address look alike. That helps, but it cannot catch every case.
§6Indexing, Security and IANA
If a URI is used as an index object, the Uri convention SHOULD be subtyped to a length appropriate for the Object Identifier (OID) it is part of. The description adds that an OID has an absolute limit of 128 subids, and that it is not efficient to have OIDs whose length approaches this limit.
The module defines no management objects, only a convention that others may import. The RFC therefore says meaningful security considerations can only be written in the MIB modules that define objects, and that this document has no impact on the security of the Internet. It also points to the security considerations of STD 66.
IANA assigned { mib-2 164 } to the URI-TC-MIB module.
If the address is used as a filing label, keep it short so the label does not get too long. The document itself holds no secrets, so it adds no new security worries.