draft-ietf-asid-x500-url-02.txt   rfc2079.txt 
X.500 URI Attribute Types and Object Class Mark Smith Network Working Group M. Smith
INTERNET-DRAFT University of Michigan Request for Comments: 2079 Netscape Communications
11 October 1995 Category: Standards Track January 1997
Definition of X.500 Attribute Types and an Object Class to Hold Definition of an X.500 Attribute Type and an Object Class to Hold
Uniform Resource Identifiers (URIs) Uniform Resource Identifiers (URIs)
Filename: draft-ietf-asid-x500-url-02.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working This document specifies an Internet standards track protocol for the
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Distribution of this memo is unlimited. Editorial comments should be
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place on the IETF ASID mailing list (ietf-asid@umich.edu).
This Internet Draft expires April 11, 1995.
Abstract Abstract
Uniform Resource Locators (URLs) are being widely used to specify the Uniform Resource Locators (URLs) are being widely used to specify the
location of Internet resources. There is an urgent need to be able location of Internet resources. There is an urgent need to be able
to include URLs in the X.500 directory, and a desire to include other to include URLs in directories that conform to the LDAP and X.500
types of Uniform Resource Identifiers (URIs) as they are defined. A information models, and a desire to include other types of Uniform
number of independent groups are already experimenting with the Resource Identifiers (URIs) as they are defined. A number of
inclusion of URLs in the X.500 directory. This document builds on independent groups are already experimenting with the inclusion of
the experimentation to date and defines two new attribute types and URLs in LDAP and X.500 directories. This document builds on the
an auxiliary object class to allow URIs, including URLs, to be stored experimentation to date and defines a new attribute type and an
in directory entries in a standard way. auxiliary object class to allow URIs, including URLs, to be stored in
directory entries in a standard way.
Background and Intended Usage Background and Intended Usage
Uniform Resource Locators (URLs) as defined by [1] are the first of Uniform Resource Locators (URLs) as defined by [1] are the first of
several types of Uniform Resource Identifiers (URIs) being defined by several types of Uniform Resource Identifiers (URIs) being defined by
the IETF. This document defines two X.500 [2,3] attribute types the IETF. URIs are widely used on the Internet, most notably within
(labeledURI and labeledURL) and an auxiliary object class Hypertext Markup Language [2] documents. This document defines an
(labeledURIObject) to hold all types of URIs, including URLs. It is X.500 [3,4] attribute type called labeledURI and an auxiliary object
assumed that as other kinds of URIs are defined, additional attribute class called labeledURIObject to hold all types of URIs, including
types may be created to support storing them in directory entries. URLs. These definitions are designed for use in LDAP and X.500
directories, and may be used in other contexts as well.
The rationale for adding separate attribute types for the different
kinds of URIs is to support efficient programmatic access to specific
types of URIs. For example, if an indexing service is only
interested in URLs, having them available in their own attribute
makes pulling them out of a directory entry straightforward and
efficient.
It is intended that the schema elements defined in this document will
be progressed according to the process defined by the Internet X.500
Schema Working Group [4].
Schema Definition of the labeledURL Attribute Type
Name: labeledURL
ShortName: None
Description: Uniform Resource Locator with optional label
OID: umichAttributeType.41 (1.3.6.1.4.1.250.1.41)
Syntax: caseExactString
SizeRestriction: None
SingleValued: False
Discussion of the labeledURL Attribute Type
The labeledURL attribute type has the caseExactString syntax (since
URLs are case-sensitive) and it is multivalued. Values placed in the
attribute should consist of a URL as defined in [1] optionally
followed by one or more space characters and a label. Since space
characters are not allowed to appear un-encoded in URLs, there is no
ambiguity about where the label begins. Multiple labeledURL values
will generally indicate different resources that are all related to
the X.500 object, but may indicate different locations for the same
resource.
The label is used to describe the resource to which the URL points,
and is intended as a friendly name fit for human consumption. This
document does not propose any specific syntax for the label part.
Note that in some cases it may be helpful to include in the label
some indication of the kind and/or size of the resource referenced by
the URL.
Note that the label may include any characters allowed by the
caseExactString syntax, but that the use of non-IA5 (non-ASCII)
characters is discouraged as not all directory clients may handle
them in the same manner.
Some examples of valid labeledURL values (the first does not have a
label):
ftp://ds.internic.net/rfc/rfc822.txt
http://www.umich.edu/ University of Michigan Home Page
http://champagne.inria.fr/Unites/rennes.gif Rennes [photo]
Schema Definition of the labeledURI Attribute Type Schema Definition of the labeledURI Attribute Type
Name: labeledURI Name: labeledURI
ShortName: None ShortName: None
Description: Uniform Resource Identifier with optional label Description: Uniform Resource Identifier with optional label
OID: umichAttributeType.57 (1.3.6.1.4.1.250.1.57) OID: umichAttributeType.57 (1.3.6.1.4.1.250.1.57)
Syntax: caseExactString Syntax: caseExactString
SizeRestriction: None SizeRestriction: None
SingleValued: False SingleValued: False
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optionally followed by one or more space characters and a label. optionally followed by one or more space characters and a label.
Since space characters are not allowed to appear un-encoded in URIs, Since space characters are not allowed to appear un-encoded in URIs,
there is no ambiguity about where the label begins. At the present there is no ambiguity about where the label begins. At the present
time, the URI portion must comply with the URL specification [1]. time, the URI portion must comply with the URL specification [1].
Multiple labeledURI values will generally indicate different Multiple labeledURI values will generally indicate different
resources that are all related to the X.500 object, but may indicate resources that are all related to the X.500 object, but may indicate
different locations for the same resource. different locations for the same resource.
The label is used to describe the resource to which the URI points, The label is used to describe the resource to which the URI points,
and is intended as a friendly name fit for human consumption. This and is intended as a friendly name fit for human consumption. This
document does not propose any specific syntax for the label part. document does not propose any specific syntax for the label part. In
Note that in some cases it may be helpful to include in the label some cases it may be helpful to include in the label some indication
some indication of the kind and/or size of the resource referenced by of the kind and/or size of the resource referenced by the URI.
the URI.
Note that the label may include any characters allowed by the Note that the label may include any characters allowed by the
caseExactString syntax, but that the use of non-IA5 (non-ASCII) caseExactString syntax, but that the use of non-IA5 (non-ASCII)
characters is discouraged as not all directory clients may handle characters is discouraged as not all directory clients may handle
them in the same manner. them in the same manner. If non-IA5 characters are included, they
should be represented using the X.500 conventions, not the HTML
conventions (e.g., the character that is an "a" with a ring above it
should be encoded using the T.61 sequence 0xCA followed by an "a"
character; do not use the HTML escape sequence "&aring").
Examples of labeledURI Attribute Values
An example of a labeledURI attribute value that does not include a
label:
ftp://ds.internic.net/rfc/rfc822.txt
An example of a labeledURI attribute value that contains a tilde
character in the URL (special characters in a URL must be encoded as
specified by the URL document [1]). The label is "LDAP Home Page":
http://www.umich.edu/%7Ersug/ldap/ LDAP Home Page
Another example. This one includes a hint in the label to help the
user realize that the URL points to a photo image.
http://champagne.inria.fr/Unites/rennes.gif Rennes [photo]
Schema Definition of the labeledURIObject Object Class Schema Definition of the labeledURIObject Object Class
Name: labeledURIObject Name: labeledURIObject
Description: object that contains the URI attribute types Description: object that contains the URI attribute type
OID: umichObjectClass.15 (1.3.6.1.4.1.250.3.15) OID: umichObjectClass.15 (1.3.6.1.4.1.250.3.15)
SubclassOf: top SubclassOf: top
MustContain: MustContain:
MayContain: labeledURI, labeledURL MayContain: labeledURI
Discussion of the labeledURIObject Object Class Discussion of the labeledURIObject Object Class
The labeledURIObject class is a subclass of top and may contain the The labeledURIObject class is a subclass of top and may contain the
labeledURI and labeledURL attributes. The intent is that this object labeledURI attribute. The intent is that this object class can be
class can be added to existing directory objects to allow for added to existing directory objects to allow for inclusion of URI
inclusion of URI values. This approach does not preclude including values. This approach does not preclude including the labeledURI
the labeledURI and labeledURL attribute types directly in other attribute type directly in other object classes as appropriate.
object classes as appropriate.
References Security Considerations
[1] Berners-Lee, T., Masinter, L., and McCahill, M., "Uniform Security considerations are not discussed in this memo, except to
Resource Locators (URL)", RFC 1738, CERN, Xerox Corporation, note that blindly inserting the label portion of a labeledURI
University of Minnesota, December 1994, attribute value into an HTML document is not recommended, as this may
<URL:ftp://ds.internic.net/rfc/rfc1738.txt> allow a malicious individual to include HTML tags in the label that
mislead viewers of the entire document in which the labeledURI value
was inserted.
[2] The Directory: Overview of Concepts, Models and Service. CCITT Acknowledgments
Recommendation X.500, 1988.
[3] Information Processing Systems -- Open Systems Interconnection -- Paul-Andre Pays, Martijn Koster, Tim Howes, Rakesh Patel, Russ
The Directory: Overview of Concepts, Models and Service. ISO/IEC JTC Wright, and Hallvard Furuseth provided invaluable assistance in the
1/SC21; International Standard 9594-1, 1988. creation of this document.
[4] Howes, T., Rossen, K., Sataluri, S., and Wright, R., "Procedures This material is based in part upon work supported by the National
for Formalizing, Evolving, and Maintaining the Internet X.500 Science Foundation under Grant No. NCR-9416667.
Directory Schema", Internet Draft (Work In Progress) of the Schema
Working Group, <URL:ftp://ds.internic.net/internet-drafts/
draft-howes-x500-schema-03.txt>
Security Considerations Appendix: The labeledURL Attribute Type (Deprecated)
Security considerations are not discussed in this memo. An earlier draft of this document defined an additional attribute
type called labeledURL. This attribute type is deprecated, and
should not be used when adding new values to directory entries. The
original motivation for including a separate attribute type to hold
URLs was that this would better enable efficient progammatic access
to specific types of URIs. After some deliberation, the IETF-ASID
working group concluded that it was better to simply have one
attribute than two.
Acknowledgments The schema definition for labeledURL is included here for historical
reference only. Directory client software may want to support this
schema definition (in addition to labeledURI) to ease the transition
away from labeledURL for those sites that are using it.
Paul-Andre Pays, Martijn Koster, Tim Howes, Rakesh Patel, and Russ Name: labeledURL
Wright provided invaluable assistance in the creation of this ShortName: None
document. Description: Uniform Resource Locator with optional label
OID: umichAttributeType.41 (1.3.6.1.4.1.250.1.41)
Syntax: caseExactString
SizeRestriction: None
SingleValued: False
OID: umichAttributeType.41 (1.3.6.1.4.1.250.1.41)
This material is based upon work supported by the National Science References
Foundation under Grant No. NCR-9416667.
[1] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL)", RFC 1738, CERN, Xerox Corporation,
University of Minnesota, December 1994.
<URL:ftp://ds.internic.net/rfc/rfc1738.txt>
[2] Berners-Lee, T., and D. Connolly, "Hypertext Markup Language -
2.0", RFC 1866, <URL:ftp://ds.internic.net/rfc/rfc1866.txt>
[3] The Directory: Overview of Concepts, Models and Service. CCITT
Recommendation X.500, 1988.
[4] Information Processing Systems -- Open Systems Interconnection --
The Directory: Overview of Concepts, Models and Service. ISO/IEC JTC
1/SC21; International Standard 9594-1, 1988.
Author's Address Author's Address
Mark Smith Mark Smith
University of Michigan Netscape Communications Corp.
Information Technology Division 501 E. Middlefield Rd.
535 W. William St. Mountain View, CA 94043, USA
Ann Arbor, MI 48103-4943, USA
Phone: +1 313 764-2277
Fax: +1 313 765-5140
EMail: mcs@umich.edu
This Internet Draft expires April 11, 1995. Phone: +1 415 937-3477
EMail: mcs@netscape.com
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