Presentation on theme: "1 Accessing Multiple Resources via Z39.50 Paul Miller Interoperability Focus UK Office for Library & Information Networking (UKOLN)"— Presentation transcript:
1 Accessing Multiple Resources via Z39.50 Paul Miller Interoperability Focus UK Office for Library & Information Networking (UKOLN) P.Miller@ukoln.ac.ukhttp://www.ukoln.ac.uk/ UKOLN is funded by the Library and Information Commission, the Joint Information Systems Committee (JISC) of the Higher Education Funding Councils, as well as by project funding from the JISC and the European Union. UKOLN also receives support from the Universities of Bath and Hull where staff are based.
2 Outline What is Z39.50? Some gory details –Attribute Sets, Profiles, and all… Maintenance and development Whats wrong with Z39.50? The Bath Profile The New Attribute Architecture How its used Tools, registries, etc. See http://www.ariadne.ac.uk/issue21/z3950/
3 What is Z39.50? ANSI/NISO Z39.50–1995, Information Retrieval (Z39.50): Application Service Definition and Protocol Specification ISO 23950:1998, Information and Documentation Information Retrieval (Z39.50) Application Service Definition and Protocol Specification. See http://lcweb.loc.gov/z3950/agency/1995doce.html
4 What is Z39.50? This standard specifies a client/server based protocol for Information Retrieval. It specifies procedures and structures for a client to search a database provided by a server, retrieve database records identified by a search, scan a term list, and sort a result set. Access control, resource control, extended services, and a help facility are also supported. The protocol addresses communication between corresponding information retrieval applications, the client and server (which may reside on different computers); it does not address interaction between the client and the end-user. (Z39.50–1995, page 0). See http://lcweb.loc.gov/z3950/agency/1995doce.html
5 Some gory details… Z39.50 follows client/server model But calls them Origin and Target Client/origin Server/target
8 Some gory details… Z39.50–1995 is divided into eleven Facilities InitializationSearch RetrievalResult–set–delete BrowseSort Access ControlAccounting ExplainExtended Services Termination. See http://www.ariadne.ac.uk/issue21/z3950/
9 Facilities and Services Each Facility comprises at least one Service A Service facilitates a particular interaction between Origin and Target The three key services are Init, Search, and Present. See http://www.ariadne.ac.uk/issue21/z3950/
10 Init The only Service of the Initialization Facility Origin–initiated Used to start a Z–association Origin requests a number of parameters under which the searches will be conducted Target responds, either accepting offered parameters or proposing others if necessary.
11 Search The only Service of the Search Facility Origin–initiated Used to actually conduct a search Origin specifies databases to be searched, attribute combinations, and query Target responds, identifying the number of matching results.
12 Present Main Service of the Retrieval Facility (along with Segment) Origin–initiated although Target can initiate a Segment request if the result set is very large Used to return records to the user.
13 Init for dummies Hello. Do you speak English? Hello. Yes, I do. Lets talk.
14 Search for dummies Cool. Can I have anything youve got on a place called Bristol? Ive got 25 records matching your request, and heres the first five. As you didnt specify anything else, Ive sent them to you in MARC, so I hope thats OK.
15 Present for dummies 25, eh? Can I have the first ten, please? Oh, and I really dont like MARC. If you can send Dublin Core that would be great, and if not Ill settle for some SUTRS. DC:Creator – blah DC:Title – blah …
16 Now it gets hairy… To communicate successfully, Origin and Target need to use the same Attribute Set. An Attribute Set like Bib–1 defines six forms of Attribute –Use –Relation –Truncation –Completeness –Position –Structure.
17 Use Attributes Define the access points on which a search takes place Title, author, subject, etc. See http://lcweb.loc.gov/z3950/agency/defns/bib1.html
18 Relation Attributes Defines the relationship between the search term and values stored in the database/index Less than, greater than, equal to, phonetically matched, etc.
19 Truncation Attributes Defines which part of the stored value is to be searched on Beginning of any word, end of any word, etc. Smith finds Smithsonian and not Wordsmith, and vice versa.
20 Completeness Attributes Defines how much of the stored index term must be in the search term Smith finds Smith, but not Smithsonian or the Smith, etc.
21 Position Attributes Defines where in the index the search term should be located At the start of the field, anywhere, etc.
22 Structure Attributes Specifies the form to be searched for Word, phrase, date, etc.
23 Record Syntaxes Record Syntaxes define the structure in which results are returned to the Origin. This does not mean that Targets need to store data in these formats MARC UKMARC, USMARC/MARC21, DANMARC, MARB, UNIMARC… SUTRS Simple Unstructured Text Record Syntax GRS–1 Generic Record Syntax XML.
24 Profiles Groupings of Attribute Sets, Record Syntaxes, etc. to meet specific needs Disciplinary –Cultural Heritage (CIMI) –Geospatial (GEO) Geographic/Cultural/National –Texas Profile –OPAC Network for Europe (ONE) –Conference of European National Librarians (CENL) Functional –Collections Profile Etc.
25 Z39.50 Maintenance Agency Based at Library of Congress, and officially responsible for upkeep of the standard ZIG Z39.50 Implementors Group Informal grouping of vendors, users and implementors who work to progress new areas of the standard Next meeting in Texas in January Likely to be at UKOLN in 2001. Maintenance and Development See http://www.loc.gov/z3950/agency/
26 Whats wrong with Z39.50? Profiles for each discipline Defeats interoperability? Vendor interpretation of the standard Bib–1 bloat Largely invisible to the user Seen as complicated, expensive and old–fashioned Surely no match for XML/RDF/ whatever.
27 The Bath Profile System vendors implement areas of the Z39.50 standard differently Regional, National, and disciplinary Profiles have appeared over previous years, many of which have basic functions in common Users wish to search across national/regional boundaries, and between vendors. See http://www.ukoln.ac.uk/interop–focus/ activities/z3950/int_profile/bath/
28 Learning from the past The Bath Profile is heavily influenced by ATS–1 CENL DanZIG MODELS ONE Z Texas vCUC See http://www.ukoln.ac.uk/interop–focus/ activities/z3950/int_profile/bath/
29 Learning from the past See http://www.ukoln.ac.uk/interop–focus/ activities/z3950/int_profile/bath/
30 Doing the work ZIP–PIZ–L mailing list, hosted by National Library of Canada Meeting face–to–face The UKs Joint Information Systems Committee (JISC) supported a face– to–face meeting in Bath over the summer A draft, being widely circulated for comment. See http://www.ukoln.ac.uk/interop–focus/ activities/z3950/int_profile/bath/
31 What we proposed Minimisation of defaults Where possible, every attribute is defined in the Profile (Use, Relation, Position, Structure, Truncation, Completeness) Three Functional Areas Basic Bibliographic Search & Retrieval Bibliographic Holdings Search & Retrieval Cross–Domain Search & Retrieval Three or more Levels of Conformance in each Area. See http://www.ukoln.ac.uk/interop–focus/ activities/z3950/int_profile/bath/
32 What we proposed SUTRS and one of UNIMARC or MARC21 for Bibliographic Search results Or all three at Level 1? SUTRS and Dublin Core (in XML) for Cross–Domain results Other record syntaxes also permitted, but conformant tools must support at least these.
33 The new Attribute Architecture Recognition of existing problems Probably 2–3 years away in mainstream implementations? Deals with Bib–1 bloat by identifying key attributes of value to multiple applications, and grouping them together –Utility Attribute Set (description of records) –Cross–Domain Attribute Set (description of resources, and closely related to Dublin Core element set) –Bib–2 etc.
34 The new Attribute Architecture New Attribute TypeRelation to Bib–1 Attributes Access PointUse Semantic Qualifiernew Languagenew Content Authoritynew Expansion/ Interpretation Truncation and some of Relation Normalized Weightnew
35 The new Attribute Architecture New Attribute TypeRelation to Bib–1 Attributes Hit Countnew ComparisonMost of Relation and part of Completeness Format/ StructureStructure OccurrenceCompleteness Indirectionnew Functional Qualifiernew
36 Using Z39.50 Z39.50 widely deployed in the library sector and elsewhere, although often invisibly The Origin can be either a human user or a second Origin computer –e.g. Z39.50 portals, summing resources from multiple targets Users access Z39.50 Targets using proprietary clients or, increasingly, via web interfaces –e.g. WinWillow, ZNavigator, many WOPACs.
41 Building the DNER Distributed National Electronic Resource Policy aspiration of the Joint Information Systems Committee Intended to provide greater access to JISCs Current Content Collection –RDN –AHDS –MIMAS –EDINA –The Data Archive –EDUSERVE –eLib projects etc.
42 Building the DNER Construction of Bath Profile–conformant Z39.50 Targets at data sources Construction of various Portals to facilitate access JISC Portal ? Data Centre Portals Subject Portals Data Type Portals Institutional Portals Personal Portals ?
43 Building the DNER Remaining challenges Authentication hell –Move from endless authentication to single authentication Alignment of different data types –Ordnance Survey maps at Edinburgh –Satellite imagery in Manchester –Electronic journal articles in many formats, etc. –Census data at the Data Archive –Survey data in Manchester –Chemical structures in Manchester Collection Level Description.