# LDAP URL Format

Tim Howes (tim@umich.edu)
Fri, 21 Apr 1995 09:52:16 -0400

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    Message-Id: <199504211352.JAA28837@terminator.rs.itd.umich.edu>

    From: "Tim Howes" <tim@umich.edu>

    To: uri@bunyip.com

    Subject: LDAP URL Format

    Date: Fri, 21 Apr 1995 09:52:16 -0400

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Hi there. The ASID working group has produced the attached draft, which
defines an LDAP URL format. LDAP is the lightweight directory access
protocol, used as a front-end for accessing the X.500 directory, and
soon for holding directory data of its own (i.e., not necessarily in
X.500). The format is general enough to handle both cases, and allows
pretty general access to the LDAP search capability.

The ASID group and the authors of this document would appreciate any
comments you guys have on the draft, the format itself, or the prototype
implementation mentioned in the draft. Thanks! -- Tim

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Content-Description: LDAP URL Format draft

Network Working Group Tim Howes
INTERNET DRAFT Mark Smith
University of Michigan
14 March, 1995

An LDAP URL Format
<draft-ietf-asid-ldap-format-00.txt>

1. Status of this Memo

This document is an Internet-Draft. Internet-Drafts are working docu-
ments 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 learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).

2. Abstract

LDAP is the Lightweight Directory Access Protocol, defined in [1] and
[2]. This document describes a format for an LDAP Uniform Resource
Locator which will allow World Wide Web clients to have direct access to
the LDAP protocol. While LDAP currently is used only as a front end to
the X.500 directory, the URL format described here is general enough to
handle the case of stand-alone LDAP servers (i.e., LDAP servers not
back-ended by X.500).

This document is meant to provide information to the Internet community.
The format it describes is at the experimental stage. It is anticipated
that once more experience with the format is gained, a standards track
version of this document will be pursued. Please send comments to the
authors.

Howes & Smith [Page 1]

RFC DRAFT March 1995

3. URL Definition

An LDAP URL begins with the protocol prefix "ldap" and is defined by the
following grammar.

<ldapurl> ::= "ldap://" [ <hostport> ] "/" <dn> [ "?" <attributes>
[ "?" <scope> "?" <filter> ] ]

<hostport> ::= <hostname> [ ":" <portnumber> ]

<dn> ::= a string as defined in RFC 1485

<attributes> ::= NULL | <attributelist>

<attributelist> ::= <attribute> | <attribute> [ "," <attributelist> ]

<attribute> ::= a string as defined in RFC 1487

<scope> ::= "base" | "one" | "sub"

<filter> ::= a string as defined in RFC 1558

The ldap prefix indicates an entry or entries residing in the LDAP
server running on the given <hostname> at the given <portnumber>. The
default port is TCP port 389. The <dn> is an LDAP Distinguished Name
using the string format described in [1], with any URL-illegal charac-
ters (e.g., spaces) escaped using the % method.

The <attributes> construct is used to indicate which attributes should
be returned from the entry or entries. Individual attribute names are
as defined in [3]. If the <attributes> part is omitted, all attributes
of the entry or entries should be returned.

The <scope> construct is used to specify the scope of the search to per-
form in the given LDAP server. The allowable scopes are "base" for a
base object search, "one" for a one-level search, or "sub" for a subtree
search. The default is "base".

The <filter> is used to specify the search filter to apply to entries
within the specified scope during the search. It has the format speci-
fied in [4]. The default is "(objectClass=*)".

Note that if the entry resides in the X.500 namespace, it should be
reachable from any LDAP server that is providing front-end access to the
X.500 directory. If the <hostport> part of the URL is missing, the URL
can be resolved by contacting any X.500-back-ended LDAP server.

Howes & Smith [Page 2]

RFC DRAFT March 1995

4. Examples

The following are some example LDAP URLs using the format defined above.

An LDAP URL referring to the University of Michigan entry:

ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US

This URL corresponds to a base object search of the "o=University of
Michigan, c=US" entry using a filter of (objectclass=*), requesting all
attributes.

An LDAP URL referring to only the postalAddress attribute of the Univer-
sity of Michigan entry:

ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US?postalAddress

The corresponding LDAP search operation is the same as in the previous
example, except that only the postalAddress attribute is requested.

An LDAP URL referring to the set of entries found by qyerying any
X.500-capable LDAP server and doing a subtree search of the University
of Michigan for any entry with a common name of "Babs Jensen", retriev-
ing all attributes:

ldap:///o=University%20of%20Michigan,c=US??sub?(cn=Babs%20Jensen)

An LDAP URL referring to all children of the c=GB entry:

ldap://ldap.itd.umich.edu/c=GB?objectClass?one

The objectClass attribute is requested to be returned along with the
entries.

5. Security Considerations

Security considerations are not discussed in this document.

6. Prototype Implementation Availability

There is a prototype implementation of the specification defined in this
document available. It is an extension to the libwww client library,
provided in both source and binary forms. Also included are binary ver-
sions of the Mosaic WWW client for various platforms. See the following
URL for more details:

ftp://terminator.rs.itd.umich.edu/ldap/url/

Howes & Smith [Page 3]

RFC DRAFT March 1995

7. Bibliography

[1] A String Representation of Distinguished Names. S. Kille, Request
for Comment (RFC) 1485, July 1993

[2] Lightweight Directory Access Protocol. Wengyik Yeong, Tim Howes,
Steve Kille, Request for Comment (RFC) 1487, July 1993

[3] The String Representation of Standard Attribute Syntaxes. T.
Howes, S. Kille, W. Yeong, C.J. Robbins; Request for Comment (RFC)
1488, July 1993

[4] A String Representation of LDAP Search Filters. T. Howes; Request
for Comment (RFC) 1558, December 1993

8. Acknowledgements

This material is based upon work supported by the National Science Foun-
dation under Grant No. NCR-9416667.

9. Author's Address

Tim Howes
University of Michigan
ITD Research Systems
535 W William St.
Ann Arbor, MI 48103-4943
USA
+1 313 747-4454
tim@umich.edu

Mark Smith
University of Michigan
ITD Research Systems
535 W William St.
Ann Arbor, MI 48103-4943
USA
+1 313 764-2277
mcs@umich.edu

This Internet Draft expires September 14, 1995.

Howes & Smith [Page 4]

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