1. Z39.50 A Basic Introduction Kathleen R. Murray, Ph.D. William E. Moen, Ph.D. May 2002

2. UNT Center for Digital Knowledge2 Z39.50 Standards International Standard, ISO 23950: “Information Retrieval (Z39.50): Application Service Definition and Protocol Specification” US National Standard, ANSI/NISO Z39.50 Source: http://www.loc.gov/z3950/agency/ “The standard specifies a client/server-based protocol for searching and retrieving information from remote databases.”

3. May 2002UNT Center for Digital Knowledge3 Definition Z39.50 is a protocol which specifies data structures and interchange rules that allow a client machine (called an "origin" in the standard) to search databases on a server machine (called a "target" in the standard) and retrieve records that are identified as a result of such a search. - Clifford Lynch Source: http://www.dlib.org/dlib/april97/04lynch.html

4. May 2002UNT Center for Digital Knowledge4 Client-Server Model The overall search and retrieval functions are split between the client and server Z39.50 Client is called the "Origin“ Z39.50 Server is called the “Target” Client = “Origin” Server = “Target”

5. May 2002UNT Center for Digital Knowledge5 Client-Server Model User –Enters query in local system Z39.50 Client –Translates query into Z39.50 format –Sends query to a Z39.50 server Z39.50 Server –Presents the query to database system –Returns the results to client Z39.50 Client: Translates & Sends Query Database Server: Manages Data Z39.50 Server: Queries Database & Returns Results

6. May 2002UNT Center for Digital Knowledge6 Z39.50 Client Part of the local computing system Functions –Initiating a search –Sending a query –Requesting the return of records Client = “Origin” Major Benefit: User only has to know one set of search commands for local and remote searches.

7. May 2002UNT Center for Digital Knowledge7 Z39.50 Client Types Integrated with OPAC –Allows staff and patrons to search other catalogs via Z39.50 Stand-alone –Allows staff and patrons to search other catalogs and databases via Z39.50

8. May 2002UNT Center for Digital Knowledge8 Z39.50 Server Functions –Interfaces with remote databases –Responds to messages received from “Origin” or client systems Server = “Target” Example: Provides client records that match a search query

9. May 2002UNT Center for Digital Knowledge9 Virtual Catalog Example Catalog 4 Catalog N Catalog 1 Catalog 2 Catalog 3 Z Server Z Client Z39.50 Client User Interface Resulting Virtual Catalog Single user search as multiple queries to multiple catalogs User conducts single search to single logical resource

10. May 2002UNT Center for Digital Knowledge10 Learn more about client - server architecture by viewing the tutorial! Thanks!