A/WWW Enterprises 15 July 1996 Implementing Queries with Z39.50 A. Warnock A/WWW Enterprises

A/WWW Enterprises 15 July 1996 Introduction to Z39.50 n Developed for search and retrieval n Networked, client/server environment n Tested by working information scientists (Z39.50 Implementor’s Group) n Commercial & public domain support (Isite from CNIDR, yaz, others) n

A/WWW Enterprises 15 July 1996 Z39.50 Requests n Init Initiate a stateful session n Search Process a query n Present Deliver results of a Search Request n Explain Get server inf. - databases, services, etc

A/WWW Enterprises 15 July 1996 Z39.50 Capabilities - Search n Arbitrary queries - text, numeric, words, phrases, fields n Stateful n Multiple search engine APIs n Query for capabilities (EXPLAIN) n Record & Database-level security n Authentication

A/WWW Enterprises 15 July 1996 Z39.50 Capabilities - Retrieval n Multiple formats (unstructured text, HTML, US MARC, tagged text,...) n Element sets (brief records, full records, other combinations of fields/attributes) n Permanent result sets n Automated data conversion

A/WWW Enterprises 15 July 1996 Attribute Sets n Attributes define how the query is specified Use: field names Relation: comparisons Position: location in field Structure: word/phrase/key/etc Truncation: left/right/none/etc Completeness: subfield/field

A/WWW Enterprises 15 July 1996 Attributes & Element Sets n Supported Attribute Sets BIB-1  GILS  GEO STAS n Element Sets define retrievable sets of use attributes Brief record Full record Summary record (GEO)

A/WWW Enterprises 15 July 1996 Record Syntaxes n Z39.50 allows specification of a “Preferred Record Syntax” for results SUTRS (unstructured text) HTML USMARC GRS-1 (tagged, generalized syntax)

A/WWW Enterprises 15 July 1996 Profiles - GEO and Otherwise n Profiles define allowed attributes and element sets n Usually domain specific - ATS-1, GILS, WAIS, GEO, Digital Collections, Museum Collections n Supported by external agreement between client & server (currently) i.e., a GEO client talks to a GEO server

A/WWW Enterprises 15 July 1996 Sample Query n Step 1 - Establish Connection Issue INIT request –Version –ID/Authentication –Options –Message & Record sizes –Implementation information –User Information Field –Other information

A/WWW Enterprises 15 July 1996 Sample Query n Step 2 - Send the query Issue SEARCH request –Query Type –Query –Database names –Result Set name –Element Set names –Preferred Record Syntax

A/WWW Enterprises 15 July 1996 Sample Query n Step 2a: RPN query form AND(AND(AND( landsat7tm[(1,3000),(2,3),(3,0),(4,2),(5,100),(6,0)], (41N,112.5W,center,512,512)[(1,1111),(2,7),(3,0),(4, 111), (5,100),(6,0)]), maximum[(1,3403),(2,2),(3,0),(4,2),(5,100),(6,0)]), maximum[(1,3404),(2,2),(3,0),(4,2),(5,100),(6,0)])

A/WWW Enterprises 15 July 1996 Sample Query n Step 3 - Get Results Issue PRESENT request –Number of records requested –Start Position –Result Set ID –Element Set names (opt.) –Preferred Record Syntax (opt.) –Max Segment count/size

A/WWW Enterprises 15 July 1996 Critique n Hard to read for humans but easily parsed by machines n Unambiguous n Easily generalized n Why? Because all the necessary ingredients are covered by the protocol specification

A/WWW Enterprises 15 July 1996 Summary n Z39.50 contains all the elements necessary to implement a profile n GEO profile already contains some of what’s required to implement geo- spatial queries n A profile isn’t part of the standard, but is an agreement among users - it can be extended