Networking Working Group Wengyik Yeong
INTERNET-DRAFT Performance Systems International
November 1991
Representing Public Archives in the Directory
Status of this Memo
This draft document will be submitted to the RFC Editor as an
informational document. Distribution of this memo is unlimited.
Please send comments to the author, or the discussion group <osi-
ds@cs.ucl.ac.uk>.
Abstract
The proliferation of publicly accessible archives in the Internet has
created an ever-widening gap between the fact of the existence of
such archives, and knowledge about the existence and contents of
these archives in the user community. Related to this problem is the
problem of also providing users with the necessary information on the
mechanisms available to retrieve such archives. In order for the
Internet user community to better avail themselves of this class of
resources, there is a need for these gaps in knowledge to be bridged.
Given the richness of its existing information framework, it is
interesting to experiment with the use of the Directory as a solution
to these information dissemination problems. This document specifies
the schema necessary to provide the infrastructure for such
experimental efforts.
Note that it is the purpose of this schema to provide for the
representation of publicly available archives of the most generic
nature in the Directory. It is explicitly beyond the scope of this
document to provide the necessary support for the representation of
specialized archives with more than a minimum of structuring
information. The representation of specialized archives such as
document repositories or mail archives is left to other schema
specifications which will emerge as the problems of information
access are better understood.
Information Model
At the highest level, the information model underlying this document
envisions that a user will use the Directory to identify individual
archives of interest, but that retrieval services based on non-X.500
based technologies will provide the mechanism for actually retrieving
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archives. As such, the role of the Directory is envisioned to be
- to provide the information necessary for a user to successfully
identify archives of interest;
- to identify the location of the retrieval service to which
access is required to retrieve archives of interest;
- to identify the mechanisms necessary to successfully retrieve
archives of interest.
For example, in this model, a user wishing to obtain a given software
package would consult the Directory to locate archive retrieval ser-
vices providing access to the software in question and to discover
that access to the archives is provided through ftp by some archive
retrieval service. The user would then retrieve the desired software
through the archive service by way of anonymous ftp.
It is important to note that in this model, an archive service is an
abstract entity that provides access to archives, and is not bound to
any particular technology base. As such, an archive service may at
the option of its operators provide access to archives by means of
multiple protocols.
In modeling the existence of archive services and archives, it is
necessary to strike a compromise between allowing for the distribu-
tion of information in the Directory, and the desire to provide an
abstraction of an archive as an object with no extraneous structuring
information. To this end, the approach is taken that archives and
related archive services are represented as a two-level hierarchy,
with archive services representing the first level of the hierarchy,
and the archives themselves occurring as objects below the archive
service that provides access to them. In this way, each provider of
publicly accessible archives may at their option provide and manage
their own information, while the abstraction of the archive as a sin-
gle object is preserved.
Representation of Archive Retrieval Services
Archive Retrieval Services are represented as objects of class appli-
cationProcess, with RDNs formed from a commonName attribute with
value naming the Internet host from which the service is provided.
For example, the anonymous ftp service on the Internet host
uu.psi.com should have the RDN "commonName=uu.psi.com".
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Representation of Archives
This schema represents archives as objects of the class publicAr-
chive, as defined below. For the purposes of representation, each
file to which an archive retrieval service provides access is con-
sidered an archive.
Consistent with the goal of representing archives in a generic
fashion, a least common denominator approach is taken, with only a
minimum of information felt to be common across many archives being
selected for inclusion as attributes of an archive object. These
attributes are
- An Archive Identifier to provide a unique identification of the
archive. The Archive Identifier has case-sensitive string
values containing the complete specification of an archive file,
including any device or path information necessary to uniquely
identify the archive file to the archive retrieval service.
- An Archive Path used to identify the archive for searching pur-
poses. The Archive Path is similar to the Archive Identifier,
differing only in that it has case-insensitive string values. It
is present only to facilite case-insensitive searching.
- An Archive Name that names an archive. The Archive Name takes on
case-insensitive string values that need not be unique.
- An Archive Location that provides location information for the
archive, as well as the access method required to obtain the
archive from the archive retrieval service. The values taken on
by the Archive Location attribute have a complex syntax.
- An Archive Size to denote the size of the archive file. Archive
Size values are expressed as integers.
- An Archive Publisher representing the person(s) or
organization(s) that made the archive available. Archie Pub-
lisher attributes take on case-insensitive string values.
- Archive Version, Obsoletes/Obsoleted-By, Updates/Updated-By and
See-Also attributes to relate an archive to other archives for
revision control and other purposes. The Archive Version attri-
bute takes on a case-insensitive string value, while the other
attributes all take on Distinguished Name (the DNs of the
related archives) values.
- A Description to provide any additional information to users.
The Description attribute takes on case-insensitive string
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values, and contains any additional information that the archive
service provider may see fit to provide.
- Keywords and Subject attributes that have their usual semantics,
and are provided to facilitate searching. Both attributes take
on case-insensitive string values.
Examples
Suppose that a site, "uu.psi.com" ran an archive retrieval service by
means of anonymous ftp, and that the contents of the anonymous ftp
hierarchy consisted of the files
README
ls-lR
and the file "bind.tar.Z" in the directory "pub"
pub/bind.tar.Z
Then, assuming that: the DSA providing access to information on the
"uu.psi.com" archive service was based on QUIPU software; and the DSA
was named "Horned Fish" and occurred in the global DIT immediately
subordinate to c=US; then, if the QUIPU notational conventions are
used, the entry for "uu.psi.com" could look like
cn=uu.psi.com
objectClass= applicationProcess & quipuNonLeafObject & quipuOb-
ject
accessControlList= others # read # child
accessControlList= others # read # entry
accessControlList= others # read # default
masterDSA= c=US@cn=Horned Fish
while the entries for the three files that the "uu.psi.com" archive
service provides access to would respectively look like
archiveIdentifier= ./README
objectClass= quipuObject & publicArchive
archiveName= README
archivePath= ./README
archiveSize= 145
archiveVersion= Oct 21 1991
archiveLocation= ftp $ uu.psi.com $ . $ README
archivePublisher= PSI Inc.
accessControlList= others # read # default
accessControlList= others # read # entry
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archiveIdentifier= ./ls-lR
objectClass= quipuObject & publicArchive
archiveName= ls-lR
archivePath= ./ls-lR
archiveSize= 23056
archiveVersion= Nov 18 1991
archiveLocation= ftp $ uu.psi.com $ . $ ls-lR
archivePublisher= PSI Inc.
accessControlList= others # read # default
accessControlList= others # read # entry
archiveIdentifier= pub/bind.tar.Z
objectClass= quipuObject & publicArchive
archiveName= bind.tar.Z
archivePath= pub/bind.tar.Z
archiveSize= 447001
archiveVersion= Oct 3 1990
archiveLocation= ftp $ uu.psi.com $ . $ ls-lR
accessControlList= others # read # default
accessControlList= others # read # entry
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Appendix: Definitions
The following are the definitions of the Public Archive object,
and those of its attributes not already defined elsewhere.
publicArchive OBJECT-CLASS
SUBCLASS OF top
MUST CONTAIN {
archiveIdentifier,
archiveName,
archiveLocation }
MAY CONTAIN {
archivePath,
archiveSize,
archivePublisher,
archiveVersion,
description,
seeAlso,
obsoletesArchive,
obsoletedByArchive,
updatesArchive,
updatedByArchive,
keywords,
subject }
archiveIdentifier ATTRIBUTE
WITH ATTRIBUTE SYNTAX caseExactStringSyntax
archiveName ATTRIBUTE
WITH ATTRIBUTE SYNTAX caseIgnoreStringSyntax
archiveLocation ATTRIBUTE
WITH ATTRIBUTE SYNTAX documentStoreSyntax
archivePath ATTRIBUTE
WITH ATTRIBUTE SYNTAX caseIgnoreStringSyntax
archiveSize ATTRIBUTE
WITH ATTRIBUTE SYNTAX integerSyntax
archivePublisher ATTRIBUTE
WITH ATTRIBUTE SYNTAX caseIgnoreStringSyntax
archiveVersion ATTRIBUTE
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WITH ATTRIBUTE SYNTAX caseIgnoreStringSyntax
obsoletesArchive ATTRIBUTE
WITH ATTRIBUTE SYNTAX distinguishedNameSyntax
obsoletedByArchive ATTRIBUTE
WITH ATTRIBUTE SYNTAX distinguishedNameSyntax
updatesArchive ATTRIBUTE
WITH ATTRIBUTE SYNTAX distinguishedNameSyntax
obsoletedByArchive ATTRIBUTE
WITH ATTRIBUTE SYNTAX distinguishedNameSyntax
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