2. Manifestations Z39.50-1988 ISO TC46/WG4/SC4 10162/3 SR Z39.50-1992 Z39.50-1995

3. Z39.50-1988 “Future Services” Z39.50-1992 “Future Service” Z39.50-1995 “Facility”

4. Z39.50-1988 Foreword “Future Services” List Databases List Access Points List Elements List Element Set List Element Sets

5. Z39.50-1992 Foreword “Future Services” Explain –to allow an origin to obtain details of the target implementation, including databases available for searching, data elements in records of a specified database, element sets supported, elements within a specified element set, attribute sets supported, attributes supported within a supported attribute set, diagnostic sets, and record syntaxes.

6. Z39.50-1995 “Explain Facility” Explain database – IR-Explain-1 accessed via Z39.50 Search and Present services Explain Attribute set – exp-1 Explain syntax

7. Z39.50-1988 ISO TC46/WG4/SC4 10162/3 SR Z39.50-1992 z39.50-1995

9. Contributors Makx Dekkers Liv Holm Cliff Lynch Mark Needleman Bob Waldstein Mark Hinnebusch Denis Lynch Ray Denenberg

10. Rationale (Denis Lynch 1997) Many clients don’t know their servers –Users point clients at new servers –Servers add or change databases & services Clients need dynamic information –Server hours of operation –Billing rates –Supported attribute combinations –Field labels

11. Target Info (D. Lynch) One TargetInfo record per server –Target name –database combinations –Message of the day –Contact and access information –Network addresses

12. Database Info One DatabaseInfo record per database –Database name –Databases that can be searched with this one –Databases that are subsets of this one –Attribute sets, syntaxes, schemas, query types... –Copyright and contact information

13. TagSetInfo – all tags defined in a tagset SchemaInfo –Mapping of tagset numbers to tagsets –The record structure RecordSyntaxInfo –describes the record structure AttributeSetInfo –lists every attribute

14. Attribute Details –May list patterns for legal combinations { { { Use, {4, 16, 24} }, { Structure, All } }, { { Use, 1001 }, { Structure, 2 } } }

15. Term Lists One TermListInfo per database, –lists “indexes” –link to TermListDetails –A title, for display to users –A search cost hint (optimized, expensive…) –Is it scannable TermListDetails

16. Term Lists TermListDetails: may apply to many databases –Attribute combinations that access this term list –More info about scanning –Sample terms

17. Element Specification ElementSetDetails for Element Set Names RetrievalRecordDetails for CompSpec –Mapping of schema elements to record elements

18. Sort Information Sort keys available for database Map of elements and attributes

19. Extended Services Supported services –Availability, cost… –Is package retained in ES database? –Can ES be executed synchronously?

20. Category List Explain categories supported –Dynamically discover what can be dynamically discovered

21. Miscellaneous Complexities AccessInfo TermList titles for access points Or Use attributes from AttributeCombinations AssociatedDBs SubDBs supports “more specific” function PerElementDetails for field labels ProcessingInformation

22. Issues Model –Search and retrieve from a Z39.50 database Complexities What Information does a client need?