RFC 2056 (rfc2056) - Page 1 of 7
Uniform Resource Locators for Z39
Alternative Format: Original Text Document
Network Working Group R. Denenberg
Request for Comments: 2056 Library of Congress
Category: Standards Track J. Kunze
University of California, San Francisco
D. Lynch
SilverPlatter Information Ltd.
Editors
November 1996
Uniform Resource Locators for Z39.50
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.
1. Introduction
Z39.50 is an information retrieval protocol that does not fit neatly
into a retrieval model designed primarily around the stateless fetch
of data. Instead, it models a general user inquiry as a session-
oriented, multi-step task, any step of which may be suspended
temporarily while the server requests additional parameters from the
client before continuing. Some, none, or all of these client/server
interactions may require participation of the client user, depending
only on the client software (the protocol itself makes no such
requirements).
On the other hand, retrieval of "well-known" data may be performed in
a single step, that is, with a degenerate Z39.50 session consisting
of exactly one protocol search request and response. Besides the
basic search sub-service, there are several ancillary sub-services
(e.g., Scan, Result Set Delete). Among the functions covered by
combinations of the sub-services, two core functions emerge as
appropriately handled by two separate URL schemes: the Session URL
and the Retrieval URL.
Using two schemes instead of one makes a critical distinction between
a Z39.50 Session URL, which opens a client session initialized for
interactive use by the user, and a Z39.50 Retrieval URL, which opens
and closes a client session to retrieve a specific information item.
Making this distinction at the scheme level allows the user interface
to reflect it on to the user, without requiring the user interface to
Denenberg, et. al. Standards Track