RFC 1202 (rfc1202) - Page 2 of 11
Directory Assistance service
Alternative Format: Original Text Document
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