GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc2293

Network Working Group S. Kille Request for Comments: 2293 Isode Ltd. Obsoletes: 1837 March 1998 Category: Standards Track

      Representing Tables and Subtrees in the X.500 Directory

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.

Copyright Notice

 Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

 This document defines techniques for representing two types of
 information mapping in the OSI Directory [1].
 1.  Mapping from a key to a value (or set of values), as might
     be done in a table lookup.
 2.  Mapping from a distinguished name to an associated
     value (or values), where the values are not defined by the owner
     of the entry.  This is achieved by use of a directory subtree.
 These techniques were developed for supporting MHS use of Directory
 [2], but are specified separately as they have more general
 applicability.

Kille Standards Track [Page 1] RFC 2293 Table and Subtrees in the X.500 March 1998

1 Representing Flat Tables

 Before considering specific function, a general purpose technique for
 representing tables in the directory is introduced.  The schema for
 this is given in Figure 1.  A table can be considered as an unordered
 set of key to (single or multiple) value mappings, where the key
 cannot be represented as a global name.  There are four reasons why
 this may occur:
 1.  The object does not have a natural global name.
 2.  The object can only be named effectively in the context of
     being a key to a binding.  In this case, the object will be given
     a natural global name by the table.
 3.  The object has a global name, and the table is being used
     to associate parameters with this object, in cases where they
     cannot be placed in the objects global entry.  Reasons why they
     might not be so placed include:
      o  The object does not have a directory entry
      o  There is no authority to place the parameters in the
         global entry
      o  The parameters are not global --- they only make sense
         in the  context of the table.
 4.  It is desirable to group information together as a
     performance optimization, so that the block of information may be
     widely replicated.
 A table is represented as a single level subtree.  The root of the
 subtree is an entry of object class Table.  This is named with a
 common name descriptive of the table.  The table will be located
 somewhere appropriate to its function.  If a table is private to an
 MTA, it will be below the MTA's entry.  If it is shared by MTA's in
 an organization, it will be located under the organization.
 The generic table entry contains only a description.  All instances
 will be subclassed, and the subclass will define the naming
 attribute.  Two subclasses are defined:

Kille Standards Track [Page 2] RFC 2293 Table and Subtrees in the X.500 March 1998

table OBJECT-CLASS ::= {

  SUBCLASS OF {top}
  MUST CONTAIN {commonName}
  MAY CONTAIN {manager}
  ID oc-table}

tableEntry OBJECT-CLASS ::= {

  SUBCLASS OF {top}
  MAY CONTAIN {description}                                       10
  ID oc-table-entry}

textTableEntry OBJECT-CLASS ::= {

  SUBCLASS OF {tableEntry}
  MUST CONTAIN {textTableKey}
  MAY CONTAIN {textTableValue}
  ID oc-text-table-entry}

textTableKey ATTRIBUTE ::= {

  SUBTYPE OF name                                                 20
  WITH SYNTAX DirectoryString {ub-name}
  ID at-text-table-key}

textTableValue ATTRIBUTE ::= {

  SUBTYPE OF name
  WITH SYNTAX  DirectoryString {ub-description}
  ID at-text-table-value}

distinguishedNameTableEntry OBJECT-CLASS ::= {

  SUBCLASS OF {tableEntry}                                        30
  MUST CONTAIN {distinguishedNameTableKey}
  ID oc-distinguished-name-table-entry}

distinguishedNameTableKey ATTRIBUTE ::= {

  SUBTYPE OF distinguishedName
  ID at-distinguished-name-table-key}
                   Figure 1:  Representing Tables
 1.  TextEntry, which define table entries with text keys,
     which may have single or multiple values of any type.  An
     attribute is defined to allow a text value, to support the
     frequent text key to text value mapping.  Additional values may
     be defined.

Kille Standards Track [Page 3] RFC 2293 Table and Subtrees in the X.500 March 1998

 2.  DistinguishedNameEntry.  This is used for associating
     information with globally defined objects.  This approach should
     be used where the number of objects in the table is small or very
     sparsely spread over the DIT. In other cases where there are many
     objects or the objects are tightly clustered in the DIT, the
     subtree approach defined in Section 2 will be preferable.  No
     value attributes are defined for this type of entry.  An
     application of this will make appropriate subtyping to define the
     needed values.
 This is best illustrated by example.  Consider the MTA:
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB
 Suppose that the MTA needs a table mapping from private keys to fully
 qualified domain names (this example is fictitious).  The table might
 be named as:
 CN=domain-nicknames,
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB
 To represent a mapping in this table from "euclid" to
 "bloomsbury.ac.uk", the entry:
 TextTableKey=euclid, CN=domain-nicknames,
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB
 will contain the attribute:
 TextTableValue=bloomsbury.ac.uk
 A second example, showing the use of DistinguishedNameEntry is now
 given.  Consider again the MTA:
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB
 Suppose that the MTA needs a table mapping from MTA Name to bilateral
 agreement information of that MTA. The table might be named as:
 CN=MTA Bilateral Agreements,
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB

Kille Standards Track [Page 4] RFC 2293 Table and Subtrees in the X.500 March 1998

 To represent information on the MTA which has the Distinguished Name:
 CN=Q3T21, ADMD=Gold 400, C=GB
 There would be an entry in this table with the Relative Distinguished
 Name of the table entry being the Distinguished Name of the MTA being
 referred to.  The MTA Bilateral information would be an attribute in
 this entry.  Using a non-standard notation, the Distinguished Name of
 the table entry is:
 DistinguishedNameTableKey=<CN=Q3T21, ADMD=Gold 400, C=GB>,
 CN=MTA Bilateral Agreements,
 CN=Bells, OU=Computer Science,
 O=University College London, C=GB

2 Representing Subtrees

 A subtree is similar to a table, except that the keys are constructed
 as a distinguished name hierarchy relative to the location of the
 subtree in the DIT. The subtree effectively starts a private "root",
 and has distinguished names relative to this root.  Typically, this
 approach is used to associate local information with global objects.
 The schema used is defined in Figure 2.  Functionally, this is
 equivalent to a table with distinguished name keys.  The table
 approach is best when the tree is very sparse.  This approach is
 better for subtrees which are more populated.
 The subtree object class defines the root for a subtree in an
 analogous means to the table.  Information within the subtree will
 generally be defined in the same way as for the global object, and so
 subtree OBJECT-CLASS ::= {
     SUBCLASS OF {top}
     MUST CONTAIN {commonName}
     MAY CONTAIN {manager}
     ID oc-subtree}
                   Figure 2:  Representing Subtrees
 no specific object classes for subtree entries are needed.
 For example consider University College London.
 O=University College London, C=GB

Kille Standards Track [Page 5] RFC 2293 Table and Subtrees in the X.500 March 1998

 Suppose that the UCL needs a private subtree, with interesting
 information about directory objects.  The table might be named as:
 CN=private subtree,
 O=University College London, C=GB
 UCL specific information on Inria might be stored in the entry:
 O=Inria, C=FR,
 CN=private subtree,
 O=University College London, C=GB
 Practical examples of this mapping are given in [2].

3 Acknowledgments

 Acknowledgments for work on this document are given in [2].

References

 [1] The Directory --- overview of concepts, models and services,
     1993. CCITT X.500 Series Recommendations.
 [2] Kille, S.E., "X.400-MHS use of the X.500 directory to support
     X.400-MHS routing," RFC 1801, June 1995.

4 Security Considerations

 Security considerations are not discussed in this memo.

5 Author's Address

 Steve Kille
 Isode Ltd
 The Dome
 The Square
 Richmond
 TW9 1DT
 England
 Phone:  +44-181-332-9091
 EMail:  S.Kille@ISODE.COM

Kille Standards Track [Page 6] RFC 2293 Table and Subtrees in the X.500 March 1998

A Object Identifier Assignment

mhs-ds OBJECT IDENTIFIER ::= {iso(1) org(3) dod(6) internet(1)

        private(4) enterprises(1) isode-consortium (453) mhs-ds (7)}

tables OBJECT IDENTIFIER ::= {mhs-ds 1}

oc OBJECT IDENTIFIER ::= {tables 1} at OBJECT IDENTIFIER ::= {tables 2}

oc-subtree OBJECT IDENTIFIER ::= {oc 1} oc-table OBJECT IDENTIFIER ::= {oc 2} 10 oc-table-entry OBJECT IDENTIFIER ::= {oc 3} oc-text-table-entry OBJECT IDENTIFIER ::= {oc 4} oc-distinguished-name-table-entry OBJECT IDENTIFIER ::= {oc 5}

at-text-table-key OBJECT IDENTIFIER ::= {at 1} at-text-table-value OBJECT IDENTIFIER ::= {at 2} at-distinguished-name-table-key OBJECT IDENTIFIER ::= {at 3}

              Figure 3:  Object Identifier Assignment

Kille Standards Track [Page 7] RFC 2293 Table and Subtrees in the X.500 March 1998

Full Copyright Statement

 Copyright (C) The Internet Society (1998).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Kille Standards Track [Page 8]

/data/webs/external/dokuwiki/data/pages/rfc/rfc2293.txt · Last modified: 1998/03/09 22:28 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki