Standards Review and Recommendation Publication
SRRPUB08
Directory and Locator Services
Revised February 22, 2005 Draft Version 1.5
Standards Review and Recommendations Publications (SRRPUB)
are issued by the Department of Information Resources (DIR).
They are intended to be used as guidance by Texas state agencies
and institutions of higher education and do not mandate any
particular action.
Overview
Internet usage by State agencies and institutions of higher education has grown dramatically. This expanded use of the Internet is facilitating agency-to-agency
communications via electronic mail, Electronic Commerce (EC),
Electronic Data Interchange (EDI) initiatives, transfer of
electronic files, and provision of access to statewide applications
and other types of information. Agencies are also using the
Internet to facilitate public access to government information
and services. As the state continues to expand its usage of
the Internet, there is a growing need for tools to help agencies
and the public locate information.
This document sets forth recommendations for Directory and
Locator services for Texas state agencies and institutions
of higher education.
Directory Services should be considered as the White or Yellow
Page indexes to information maintained by a state agency or
institutions of higher education that are intended to be used
to locate organizational or individual telephone numbers and
electronic mail addresses that are accessible outside the
agency on a computer network.
Locator Services would contain the indexes to information
maintained by a state agency or institution of higher education
that are specifically required by law or administrative rule
and that are accessible over a computer network.
Standards for Directory Services
Standards for Directory services have been defined by the
International Organization for Standardization (ISO) and International
Telecommunications Union (ITU) in the X.500 Directory Services
specifications. The X.500 Directory is a collection of systems
which cooperate to hold a logical database of information
about a set of objects in the real world. The Directory may
include information about organizations, people, computer
application programs and other resources.
The first X.500 standards were approved in 1988, and several
key features were added in 1993. In April 1993, DIR published
an assessment of the ISO/ITU Open Systems Interconnection
(OSI) standards and in May 1994, DIR published a draft Architecture
Framework for Information Resources Management (AFIRM). Volume
2 of the AFIRM is the Technical Reference Model and Standards
Profile, that includes issues and potential interoperability
problems associated with Directory Services based on the 1988
and 1993 specifications. Appendix F specifically addresses
a number of key features of the X.500 Directory Services for
access control and replication that are just now being implemented
by vendors.
The Internet Engineering Task Force (IETF) has published a number of Lightweight Directory Access Protocol (LDAP) standards. For a full list of the standards visit the Request for Comments (RFC) Index.
Standards for Locator Services
Locator services are currently based on the American National
Standard for Information Retrieval Application Service Definition
and Protocol Specification for Open Systems Interconnection
(OSI), developed by the National Information Standards Organization
(NISO) as Z39.50. Z39.50 is an applicationslayer protocol
within the OSI reference model developed by the International
Organization for Standardization (ISO). The standard provides
a uniform procedure for client systems to query information
resources such as online library catalogs, information files
directly available on the network, or information about sources
of other documents and publications. Version 3 of Z39.50 was
completed in December 1994, and will be officially listed
as Z39.501995.
User Requirements and Application Profile for Locator
Services
In 1994, the Interagency Working Group of the Federal Government,
published "Public Access to Government Electronic Information
- A Policy Framework." The framework provided broad guidance
on public access to government electronic information for
the use of Federal agencies in defining their own policy and
procedures. Also in 1994, the Information Infrastructure Task
Force of the National Information Infrastructure (NII) initiative
published its report on the Government Information Locator
Service (GILS). GILS is intended to help the public locate
and access information throughout the Federal Government.
In 1995, the federal government developed the GILS application
profile and published Federal Information Processing Standard
(FIPS) 192. The application profile is based primarily on
the American National Standards Institute ANSI/NISO Z39.501992
specification. GILS is a decentralized collection of servers
and associated information services that will be used by the
public either directly or through intermediaries to find public
information throughout the Federal government. The GILS profile
will enable GILS client systems to interconnect and to interoperate
with any GILS server. This profile addresses inter-system
interactions and information interchange for the GILS, but
does not specify user interface requirements, the internal
structure of databases that contain GILS Locator Records,
or search engine functionality. Some of the information resources
pointed to by GILS Locator Records, as well as the GILS server
itself, may be available electronically through other communications
protocols including the common Internet protocols that facilitate
electronic information transfer such as remote login (Telnet),
File Transfer Protocol (FTP), and electronic mail (SMTP/MIME).
Recommendations
1. Directory Services:
A. DIR should assess vendor X.500 products that comply with
the 1993 Directory Services standards and evaluate other technologies
that could be used to provide Directory Services. The Directory
Services must be available over the transport services specified
by the Internet suite of protocols (see Statewide standards
on the DIR Home Page - the URL is http://dir.state.tx.us).
B. DIR should continue to host working group meetings of
interested agencies and institutions of higher education to
assist with the definition of operational requirements for
Directory Services. After the evaluation of technologies to
support the operational requirements, DIR should publish an
implementation profile for Directory Services.
2. Locator Services:
A. DIR should recommend all Texas state government agencies
and institutions of higher education plan on using Z39.50
as the common indexing specification for locating other sources
of information.
B. DIR should consider formal adoption or endorsement of
the Texas State Library and Archives Commission's Texas Government
Information Locator Service implementation profile.
Address q uestions about the Texas Information Technology
Standards Web pages to:
DIR Standards and Architecture
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