Schema Publishing in X.500 Directory
RFC 1804

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Network Working Group                                       G. Mansfield
Request for Comments: 1804                              AIC Laboratories
Category: Experimental                                         P. Rajeev
                                                 Hughes Software Systems
                                                             S. Raghavan
                                  Indian Institute of Technology, Madras
                                                                T. Howes
                                                  University of Michigan
                                                               June 1995

                  Schema Publishing in X.500 Directory

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Abstract

   The X.500 directory provides a powerful mechanism for storing and
   retrieving information about objects of interest.  To interpret the
   information stored in the directory, the schema must be known to all
   the components of the directory. Presently, there are no means other
   than ftp to distribute schema information across the Internet.  This
   is proving to be a severe constraint as the Directory is growing.
   This document presents a solution to the schema distribution problem
   using the existing mechanisms of the directory. A naming scheme for
   naming schema objects and a meta-schema for storing schema objects is
   presented. The procedures for fetching unknown schema from the
   directory at runtime are described.

Table of Contents

   1. Introduction                                         2
   2. Schema Management                                    2
   3. Storage of Schema Information in the Directory       3
   4. Retrieval of Schema from the Directory               5
   5. The Meta-Schema                                      6
   6. References                                           9
   7. Security Considerations                              9
   8. Authors' Addresses                                  10

Mansfield, et al              Experimental                      [Page 1]
RFC 1804          Schema Publishing in X.500 Directory         June 1995

1. Introduction

   The X.500 Directory [1] is now used for a wide range of applications
   from name/address lookup to network management, from restaurant
   information to bibliographic information services. This information
   is distributed and managed across a network of many autonomous sites.
   In order to interpret the information stored in the directory, the
   components of the directory must have knowledge about the structure
   and representation (schema) of the information held within the
   directory.

   The distributed nature of the network and the relatively slow process
   of standardization have given rise to the challenging task of making
   accessible the information about the schema rules themselves.  A
   mechanism for making the schema accessible to the functional
   components of the directory is urgently required.

   The 1993 X.500 Directory Standard [2] has attempted to address the
   problem of schema management and distribution. The 1993 framework
   does provide the means for storing and retrieving schema information
   in the directory. However, the resolution of unknown OIDs will
   require both the DUA and the DSA to be compliant with [2].

   In this document we propose a solution using the existing mechanisms
   of the directory [1] itself. We present a naming scheme for naming
   schema objects and a meta-schema for storing schema objects in the
   directory.  The proposal allows the algorithmic resolution of unknown
   objects in the directory and in the absence of 1993 X.500 Directory
   Standard implementations provides an interim solution to the schema
   publishing problem.

2. Schema Management

   The storage and retrieval mechanism provided by the directory is
   powerful and flexible.  However, the key to the directory is the
   knowledge of the schema rules defined for the objects represented in
   the directory.  To facilitate the diffusion of this knowledge
   appropriate schema management mechanisms need to be designed.  Schema
   management involves:

        o Storage of schema information in the directory
        o Algorithmic access to and retrieval of schema information
          in the directory
        o Definition of rules for schema modification
        o Propagation of schema information from one component of the
          directory to other components of directory

Mansfield, et al              Experimental                      [Page 2]
RFC 1804          Schema Publishing in X.500 Directory         June 1995

   In this document we concentrate on the aspect of schema
   access/retrieval from the directory. Since schema objects are defined