Directory Assistance service
RFC 1202

Document Type RFC - Informational (February 1991; No errata)
Last updated 2013-03-02
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Network Working Group                                            M. Rose
Request for Comments: 1202       Performance Systems International, Inc.
                                                           February 1991

                      Directory Assistance Service

Status of this Memo

   This document defines a mechanism by which a user-interface may
   access a textual DAP-like interface over a TCP/IP connection.  This
   is a local mechanism.  This memo provides information for the
   Internet community.  It does not specify any standard.  Distribution
   of this memo is unlimited.

Table of Contents

   1. Introduction ..........................................   1
   1.1 An Aside ............................................    3
   2. Protocol ..............................................   3
   2.1 Control Connection ..................................    4
   2.1.1 Initialization ....................................    4
   2.1.2 Transactions ......................................    4
   2.1.2.1 INTR command ....................................    4
   2.1.2.2 STAT command ....................................    5
   2.1.2.3 QUIT command ....................................    5
   2.2 Data Connection .....................................    5
   2.2.1 Transactions ......................................    5
   2.2.2 Responses .........................................    6
   2.2.2.1 Numeric Responses ...............................    6
   2.2.2.2 'm' Response ....................................    6
   2.2.2.3 'y' Response ....................................    6
   2.2.2.4 'p' Response ....................................    7
   2.2.2.5 'e' Response ....................................    7
   2.2.2.6 'l' Response ....................................    7
   2.2.2.7 'd' Response ....................................    8
   2.2.2.8 'P' Response ....................................    8
   3. Example Interaction ...................................   9
   4. References ............................................  10
   5. Security Considerations...............................   11
   6. Author's Address......................................   11

1.  Introduction

   The OSI Directory [1] provides a powerful infrastructure for the
   retrieval of information objects.  This infrastructure can be used to
   support, e.g., white pages applications, application entity lookup,
   and so on.

Rose                                                            [Page 1]
RFC 1202              Directory Assistance Service         February 1991

   The Directory service is provided to applications through the
   Directory Access Protocol (DAP), which binds a Directory User Agent
   (DUA) to a Directory System Agent (DSA).

                                        | Directory Service
                                        |    provided via DAP
                                        |
               +-----------+            |            +-----------+
               |           |            |            |           |
               |    DUA    | <----------+----------> |    DSA    |
               |           |            |            |           |
               +-----------+            |            +-----------+
                                        |
                         Directory User |

   The DAP is an OSI application layer protocol which uses the rich OSI
   upper-layer infrastructure.  Unfortunately, the coding investment to
   implement the DAP is significant.  As such, it is difficult to host
   applications using the Directory on smaller workstations and personal
   computers.

   This memo details a local mechanism which has been successfully used
   to separate the functionality of the DAP from the complexity of
   implementing the DAP.  That is, a split-DUA model is used: the DAP is
   implemented on an entity (the "Directory Assistant"), which resides
   on a capable workstation or mainframe and exports a simpler
   interface, the "Directory Assistance" (DA) protocol, to other end-
   systems where the user-interface resides, termed the DA-client.

   Since this mechanism provides assistance to applications wishing to
   access the Directory, it is termed the "Directory Assistance" (DA)
   service:

Rose                                                            [Page 2]
RFC 1202              Directory Assistance Service         February 1991

                                        | Directory Service
                 split-DUA              |    provided via DAP
                                        |
               +-----------+            |            +-----------+
               |           |            |            |           |
               | Directory | <----------+----------> |    DSA    |
               | Assistant |            |            |           |
               |           |            |            +-----------+
               +-----------+            |
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