************************************ The Z39.50 Protocol in Plain English Clifford A. Lynch Division of Library Automation University of California Office of the President 300 Lakeside Drive, 8th floor Oakland, California 94610-3550 510/987-0522 CALUR@UCCMVSA.BITNET or CALUR@UCCMVSA.UCOP.EDU 1. What is Z39.50? Z39.50 is an American National Standard that was approved in 1988 by the National Information Standards Organization (NISO), an American National Standards Institute- (ANSI) accredited standards writing body that serves the library, information, and publishing communities. Balloting has just concluded on a revised version that will hopefully be adopted in 1992. Z39.50 is an applications-layer protocol within the OSI reference model developed by the International Standards Organization (ISO). Its purpose is to allow one computer operating in a client mode to perform information retrieval queries against another computer acting as an information server. The standard provides a uniform procedure for client computers to query information resources such as server computers supporting online library catalogs. For example, the development of a client program running on one machine may provide end users with a common means of access to a variety of information resources attached to a computer network. 2. Does Z39.50 apply only to bibliographic data, or can other types of information be accommodated? While many of the initial applications of Z39.50 are for use with bibliographic data (online public access library catalogs, for example), the protocol is actually quite general, and search attribute sets can be defined which allow the protocol to work with most other types of data. Some specialized data, such as images, may necessitate protocol extensions. Various groups are currently exploring the area of protocol extensions, and are defining attribute sets for other types of data, such as full text. 3. Is Z39.50 an International Standard? No. Z39.50 is an American National Standard. However, there is an ISO standard called Search and Retrieval, ISO 10162/10163 (service and protocol documents, respectively), which was formally adopted to International Standard (IS) status in 1991. SR is almost identical to a subset of Z39.50. Z39.50 is being revised to harmonize with SR, at which point the American National Standard will be a compatible superset of the International standard. These changes are included in the 1992 revision that has just completed balloting. 4. I have a GEAC (or any other) circulation system and a Carlyle (or any other) online public access catalog at my library. Will Z39.50 enable them to talk with each other? In theory, Z39.50 provides a basis for allowing such communication. However, attribute sets and data transfer formats appropriate to queries of circulation systems by public access catalogs have not yet been standardized, much less tested in practice. The National Information Standards Organization's Technical Plan, which defines NISO's standards development agenda, calls for work in this area. In addition, for such a link to work, both vendors not only would have to implement Z39.50, but they would have to integrate the protocol implementation with their overall software applications to create an effective intersystem link. In a joint project involving Data Research Associates (DRA), Digital Equipment Corporation (DEC), and the University of California, a link will be developed between the DRA system being installed at UC Davis and the UC campuswide MELVYL^melibm system, which would allow the MELVYL system to perform Z39.50-based searching of the circulation status file on the DRA system. This searching would allow display of information on the availability of materials as part of a MELVYL catalog display for material held at the Davis campus. 5. Can I buy a Z39.50 package? Today, I know of no organization that is marketing a Z39.50 client or server, although a number of the organizations that are doing work in this area may be willing to share code. In the longer term, Z39.50 "products" will probably fall into two categories. There will be client implementations that run on workstations or mainframes, and it is likely that at some point we may see commercial products of this type that provide a user interface to many Z39.50 servers. It seems much less likely that we will see large numbers of Z39.50 server products that stand alone since a Z39.50 server becomes an integral part of an information retrieval application. We may see vendors of information retrieval systems or database management software offering Z39.50 toolkits or support as part of their overall offerings. And it is likely that we will see vendors of library-specific applications, such as the online library catalogs offered by DRA and NOTIS, integrating Z39.50 server and/or client support in their products. 6. What vendors are currently working on Z39.50? What other efforts are underway? There are a number of efforts underway; more are starting up all the time. Here are some of the more elaborate projects (in no particular order) that we know about as of early 1992: - -- OCLC is working on Z39.50 server and client support for a range of systems, including EPIC. OCLC has also done work with NYSERNet in Z39.50. Contact: Ralph LeVan (OCLC, 6565 Frantz Rd., Dublin, OH 43017; (614) 761-6115; rrl@rsch.oclc.org). - -- RLIN is working on Z39.50 server and client support, and Z39.50 is very much part of their strategic technical plan. Contact: Madeline (Lennie) Stovel (RLG, Inc., 1200 Villa St., Mountain View, CA 94041-1100; (415) 691-2259; bl.mds@ @rlg.stanford.edu). - -- Data Research Associates (DRA), a library automation vendor, is developing Z39.50 support (client and server) for their product. They are participating in a joint project with Digital Equipment Corporation, and the University of California Office of the President to build a link between a DRA system at UC Davis campus and the MELVYL online catalog. This link would allow UC's MELVYL system to perform Z39.50-based searching of the circulation status file on the DRA system. Contacts: Clifford Lynch (University of California Office of the President, 300 Lakeside Dr., 8th floor, Oakland, CA 94610-3550; (510)987-0522; calur@uccmvsa.bitnet). Mary Heath (University of California at Davis, Shields Library, Davis, CA 95616; (916) 752-0129; mkheath@ucdavis.edu). Jim Michael (DRA, 1276 N. Warson Rd., St. Louis, MO 63132-1806; (800)325-0888; jim@ @dranet.dra.com). - -- The University of California Division of Library Automation is developing client and server Z39.50 support with help from Digital Equipment Corporation in conjunction with Pennsylvania State University. This is both for the UC IBM 3090-based MELVYL online catalog and the VAX 9000-based Pennsylvania State University LIAS, as well as for selected microcomputers. Contacts: Clifford Lynch (see above). Eric Ferrin (Pennsylvania State University, E8 Pattee Library, University Park, PA 16802; (814) 865-1818; egf@psulias.bitnet). - -- Project Mercury is a joint Carnegie-Mellon University/OCLC/Digital Equipment Corporation project to develop an electronic library at CMU. It is using Z39.50 as a central element in linking clients and servers. Contact: Bill Arms (Carnegie-Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213; (412) 268-2122; wya@andrew.cmu.edu). - -- UC Berkeley is developing an Information Server Project to coordinate campus community information. The Berkeley Information Server will use Z39.50 in a client-server architecture, with UNIX servers and initial clients targeted for workstations and personal computers. Contact: Margaret Baker (University of California, 289 Evans Hall, Berkeley, CA 94720; (510)642-5601; margaret@garnet.berkeley.edu). - -- The Linked Systems Project is organized by the Library of Congress, OCLC, and RLIN, which are currently interchanging bibliographic and authority records using a predecessor protocol to Z39.50 over an OSI network, with plans to upgrade to current Z39.50 standards. Contact: Sally McCallum (Library of Congress, Washington, DC 20540, (202) 707-5807; bb.shm@ @rlg.bitnet). - -- The Florida Center for Library Automation is working on the development of Z39.50 server and client functions for the NOTIS library automation system. They have received a US Department of Education Title II-D grant for the project. Contact: Mark Hinnebusch (Florida Center for Library Automation, Suite 320, 2002 NW 13th St., Gainesville, FL 32609; (904) 392-9020; fclmth@nervm.bitnet). - -- Thinking Machines Corporation (TMC) has distributed code for the Wide Area Information Server (WAIS), a Z39.50-based set of client and server software. Servers run under UNIX and Connection Machines; clients are available for a wider range of machines. WAIS is based on earlier work by TMC, Dow Jones, and Apple Computer on the development of a prototype information server for a Dow Jones database based on a somewhat extended and modified Z39.50 protocol. Contact: Brewster Kahle (Thinking Machines, 245 First St., Cambridge, MA 02142; (617) 234-2874; brewster@ @think.com). - -- There is an active implementors' group for Z39.50 which meets every few months, chaired by Mark Hinnebusch (Florida Center for Library Automation, Suite 320, 2002 NW 13th Street, Gainesville, FL 32609; (904) 392-9020; fcla@nervm.bitnet). They run a network mailing list called Z3950IW at nervm.nerdc.ufl.edu and nervm.bitnet. Contact: Mark Hinnebusch for subscription information. An FTP file server containing Z39.50 documents is also available. - -- A Z39.50 testbed has been established under the auspices of the Coalition for Networked Information (CNI). This group, which includes about 15 organizations, plans to develop and demonstrate multiple interoperable Z39.50 implementations running over the Internet within a short time frame. Contact: Clifford A. Lynch (see above). 7. When can I see a Z39.50 implementation? There are several running prototypes today, such as CMU Project Mercury, which was shown at EDUCOM '89 in Ann Arbor. It seems likely that you will see demonstrations at meetings of groups such as NET '92 and EDUCOM during 1992. 8. How do I get a vendor to write a Z39.50 interface? Today, most library automation local system vendors do not seem to have firm plans to implement Z39.50. You need to make it clear to vendors and potential vendors that this is an important feature for the future, and to consider needs for Z39.50 in procuring new systems. 9. How do I get a copy of the Z39.50 standard? Order from Transaction Publishers, Rutgers -- The State University, New Brunswick, NJ 08903; (201) 932-2280. Transaction publishes NISO standards. You can contact NISO at National Bureau of Standards, Administration 101, Library E-106, Gaithersburg, MD 20899; NISO@nbsenh.bitnet. You may also want to track ISO 10162/10163 (available from Omnicom Information Service, 115 Park Street, SE, Vienna, Virginia 22180; (703) 281-1135; or from NISO), and subscribe to the Z39.50 implementors' mailing list (see above). The Library of Congress is serving as the maintenance agency for Z39.50 on behalf of NISO. Contact: Sally McCallum, Network Development Office/Processing Services, Library of Congress, Washington, DC 20540; (202) 707-6237. The following books and papers may also be of interest for more information. The paper by Lynch and Preston contains a much more extensive bibliography. Henriette D. Avram. "The Linked Systems Project: Its Implications for Resource Sharing," Library Resources and Technical Services (January/March 1986), 30:1; pp. 34--46. Henriette D. Avram. "Toward a Nationwide Library Network," Journal of Library Administration (Fall/Winter 1987), 8:3/4; pp. 96--115. Henriette D. Avram. "LSP and Library Network Services in the Future," EDUCOM Bulletin (Summer/Fall 1988), 23:2/3; pp. 52--58. Henriette D. Avram. "Building a Unified Information Network," EDUCOM Bulletin (Winter 1988), 23:4; pp. 11--14. Michael Buckland and Clifford Lynch. "National and International Implications of the Linked Systems Protocol for Online Bibliographical Systems," Cataloging and Classification Quarterly (Spring 1988), 8:3/4; pp. 15--33. Wayne E. Davison. "The WLN/RLG/LC Linked Systems Project," Information Technology and Libraries (March 1983), 2:1; pp. 34--46. Ray Denenberg. "Linked Systems Project, Part 2: Standard Network Connection," Library Hi Tech (1985), 3:1, Issue 10; pp. 71--79. Ray Denenberg; Bob Rader; Thomas P. Brown; Wayne Davison; and Fred Lauber. "Implementation of the Linked Systems Project: A Technical Report. Part One: Library of Congress. Part Two: The Western Library Network. Part Three: The Research Libraries Group. Part Four: OCLC," Library Hi Tech (1985), 3:3, Issue 11; pp. 87--107. Judith Fenly and Beacher Wiggens (eds.). The Linked Systems Project: A Networking Tool for Libraries (Dublin, OH: OCLC, Inc., 1988). Clifford A. Lynch. "Library Automation and the National Research Network," EDUCOM Review (Fall 1989), 24:3; pp. 21--26. Clifford A. Lynch. "Access Technology for Network Information Resources," CAUSE/EFFECT (Summer 1990); pp. 15--20. Clifford A. Lynch. "Information Retrieval as a Network Application," Library Hi Tech (1990), 8:4, Issue 32, pp. 59-74. Clifford A. Lynch. "The Z39.50 Information Retrieval Protocol: An Overview and a Status Report," Computer Communication Review (January 1991), 21:1; pp. 58--70. Clifford A. Lynch. "The Client-Server Model in Information Retrieval," Interfaces for Information Retrieval (Martin Dillon, ed.) (Westport, CT: Greenwood Press, 1991); pp. 301--318. Clifford A. Lynch and Cecilia M. Preston. "Internet Access to Information Resources," Annual Review of Information Science and Technology (ARIST) Volume 25 (New York, NY: Elsevier, 1990); pp. 263--312. Sally H. McCallum. "Linked Systems Project, Part 1: Authorities Implementation," Library Hi Tech (1985), 3:1, Issue 10; pp. 61--68. Michael J. McGill. "Z39.50 Benefits for Designers and Users," EDUCOM Review (Fall 1989), 24:3; pp. 27--30. Michael J. McGill; Larry L. Learn; and K.G. Thomas. "A Technical Evaluation of the Linked Systems Project Protocols in the Name Authority Distribution Application," Information Technology and Libraries (December 1987), 6:4; pp. 253--265. 10. Why should I care about Z39.50? Why is it important to my library? If it's so important why haven't I heard more about it? Z39.50 is important because it is the best technology we have today to permit a single user interface to access the multiplicity of information resources becoming available on the national network. The need for Z39.50 is just now becoming clear to a larger community as network information is becoming a more serious issue. You might want to become involved in the overall movement towards network information resources. Write the ARL/EDUCOM/CAUSE Coalition for Networked Information (Paul Peters, Director, 1527 New Hampshire Ave., NW, Washington, DC 20035; (202) 232-2466; paul@cni.org).